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Ultimate Calibration2nd Edition



Preface by the CEO of Beamex Group 7

QUALITY, REGULATIONS AND TRACEABILITY

Quality standards and industry regulations 11

A basic quality calibration program 35

Traceable and efficient calibrations in the process industry 57

CALIBRATION MANAGEMENT AND MAINTENANCE

Why Calibrate? What is the risk of not calibrating? 73

Why use software for calibration management? 79

How often should instruments be calibrated? 89

How often should calibrators be calibrated? 97

Paperless calibration improves quality and cuts costs 101

Intelligent commissioning 107

Successfully executing a system integration project 115

CALIBRATION IN INDUSTRIAL APPLICATIONS

The benefits of using a documenting calibrator 125

Calibration of weighing instruments Part 1 131

Calibration of weighing instruments Part 2 137

Calibrating temperature instruments 143

Calculating total uncertainty of temperature calibration with a dry block 149

Fieldbus transmitters must also be calibrated 157

Configuring and calibrating smart instruments 163

Calibration in hazardous environments 169

The safest way to calibrate to calibrate Fieldbus instruments 175

APPENDIX: Calibration terminology A to Z 181

Contents



6



7

Calibrators, calibration software and other related equipment

have developed significantly during the past few decades in

spite of the fact that calibration of measurement devices as

such has existed for several thousands of years.

Presently, the primary challenges of industrial metrology and

calibration include how to simplify and streamline the entire

calibration process, how to eliminate double work, how to reduce

production down-time, and how to lower the risk of human errors. All

of these challenges can be tackled by improving the level of system

integration and automation.Calibration and calibrators can no longer be considered as isolated,

stand-alone devices, systems or work processes within a company or

production plant. Just like any other business function, calibration

procedures need to be automated to a higher degree and integrated to

achieve improvements in quality and eff iciency. In this area, Beamex

aims to be the benchmark in the industry.

This book is the 2nd edition of Ultimate Calibration. The main

changes to this edition include numerous new articles and a new

grouping of the articles to make it easier to find related topics. The

new topics covered in the edition mainly discuss paperless calibration,

intelligent commissioning, temperature calibration and configuring,

and calibration of smart instruments.

This book is the result of work that has taken place between 2006

and 2012. A team of experts in industry and calibration worldwide has

put forth effort to its creation.

On behalf of Beamex, I would like to thank all of the people who

have contributed to this book. I want to express my special thanks to

Pamela at Beamex Marketing, who was the key person in organizing

and leading the project for the 2nd edition. I hope this book will assist

you in learning new things and in providing fresh, new ideas. Enjoy

your reading!

raimo ahola, ceo, beamex group

Preface



Quality,Regulations and

Traceability



11

Before going into what the current standards and regulations

actually state, here is a reminder from times past about

measurement practices and how important they really are.Immersion in water makes the straight seem bent; but reason, thus

confused by false appearance, is beautifully restored by measuring,

numbering and weighing; these drive vague notions of greater or less

or more or heavier right out of the minds of the surveyor, the computer,

and the clerk of the scales. Surely it is the better part of thought that

relies on measurement and calculation. (Plato, The Republic, 360 B.C.)

There shall be standard measures of wine, beer, and corn…

throughout the whole of our kingdom, and a standard width of dyed

russet and cloth; and there shall be standard weights also. (Clause 35,

Magna Carta, 1215)

When you can measure what you are speaking about and express

it in numbers, you know something about it; but when you cannot

express it in numbers, your knowledge is of a meager and unsatisfactory

kind. It may be the beginning of knowledge, but you have scarcely, in

your thoughts, advanced to the stage of science. (William Thomson,

1st Baron Kelvin, GCVO, OM, PC, PRS, 26 June 1824–17 December

1907; A.K.A. Lord Kelvin).1

One of the earliest records of precise measurement is from Egypt.

The Egyptians studied the science of geometry to assist them in the

construction of the Pyramids. It is believed that about 3000 years B.C.,

the Egyptian unit of length came into being.

The “Royal Egyptian Cubit” was decreed to be equal to the length

of the forearm from the bent elbow to the tip of the extended middle

Calibration requirements

according to quality standards

and industry regulations



12

finger plus the width of the palm of the hand of the Pharaoh or Kin

ruling at that time.2

The “Royal Cubit Master” was carved out of a block of granite t

endure for all times. Workers engaged in building tombs, temple

pyramids, etc. were supplied with cubits made of wood or granite. Th

Royal Architect or Foreman of the construction site was responsible fomaintaining & transferring the unit of length to workers instrument

They were required to bring back their cubit sticks at each full moo

to be compared to the Royal Cubit Master.

Failure to do so was punishable by death. Though the punishmen

prescribed was severe, the Egyptians had anticipated the spirit of th

present day system of legal metrology, standards, traceability an

calibration recall.

With this standardization and uniformity of length, the Egyptian

achieved surprising accuracy. Thousands of workers were engaged i

building the Great Pyramid of Giza. Through the use of cubit stick

they achieved an accuracy of 0.05%. In roughly 756 feet or 230.3627meters, they were within 4.5 inches or 11.43 centimeters.

The need for calibration has been around for at least 5000 year

In today’s calibration environment, there are basically two types o

requirements: ISO standards and regulatory requirements. The bigge

difference between the two is simple – ISO standards are voluntary, an

regulatory requirements are mandatory. If an organization voluntee

to meet ISO 9000 standards, they pay a company to audit them to th

standard to ensure they are following their quality manual and ar

within compliance. On the other hand, if a company is manufacturin

a drug that must meet regulatory requirements, they are inspecte

by government inspectors for compliance to federal regulations. I

the case of ISO standards, a set of guidelines are used to write thei

quality manual and other standard operating procedures (SOPs) an

they show how they comply with the standard. However, the federa

regulations specify in greater detail what a company must do to mee

the requirements set forth in the Code of Federal Regulations (CFRs

In Europe, detailed information for achieving regulatory complianc

is provided in Eudralex - Volume 4 of “The rules governing medicina

products in the European Union”.

The Pharmaceutical Inspection Convention and Pharmaceutica

Inspection Co-operation Scheme (PIC/S) aims to improv

harmonisation of Good Manufacturing Practice (GMP) standard

and guidance documents.



13

Calibration requirements according to the U. S. Food and Drug

Administration (FDA)

Following are examples of some of the regulations required by

the FDA, and what they say about calibration and what must be

accomplished to meet the CFRs. Please note that European standardsare similar to FDA requirements. Listed below are several different

parts of 21CFR, that relate to the calibration of test equipment in

different situations and environments.

TITLE 21 – FOOD AND DRUGS

CHAPTER I – FOOD AND DRUG ADMINISTRATION

DEPARTMENT OF HEALTH AND HUMAN SERVICES

SUBCHAPTER H – MEDICAL DEVICES

PART 820 QUALITY SYSTEM REGULATION 22

Subpart A – General Provisions

§ 820.1 – Scope.

§ 820.3 – Definitions.

§ 820.5 – Quality system.

Subpart B – Quality System Requirements

§ 820.20 – Management responsibility.

§ 820.22 – Quality audit.

§ 820.25 – Personnel.

Subpart C – Design Controls

§ 820.30 – Design controls.

Subpart D – Document Controls

§ 820.40 – Document controls.

Subpart E – Purchasing Controls

§ 820.50 – Purchasing controls.

Subpart F – Identification and Traceability

§ 820.60 – Identification.

§ 820.65 – Traceability.

Subpart G – Production and Process Controls

§ 820.70 – Production and process controls.

§ 820.72 – Inspection, measuring, and test equipment.

§ 820.75 – Process validation.



14

Subpart H – Acceptance Activities

§ 820.80 – Receiving, in-process, and finished device acceptance.

§ 820.86 – Acceptance status.

Subpart I – Nonconforming Product

§ 820.90 – Nonconforming product.

Subpart J – Corrective and Preventive Action

§ 820.100 – Corrective and preventive action.

Subpart K – Labeling and Packaging Control

§ 820.120 – Device labeling.

§ 820.130 – Device packaging.

Subpart L – Handling, Storage, Distribution, and Installation

§ 820.140 – Handling.

§ 820.150 – Storage.

§ 820.160 – Distribution.

§ 820.170 – Installation.

Subpart M – Records

§ 820.180 – General requirements.

§ 820.181 – Device master record.

§ 820.184 – Device history record.

§ 820.186 – Quality system record.

§ 820.198 – Complaint files.

Subpart N – Servicing

§ 820.200 – Servicing.

Subpart O – Statistical Techniques

§ 820.250 – Statistical techniques.

[Code of Federal Regulations]

[Title 21, Volume 8]

[Revised as of April 1, 2012]

[CITE: 21CFR820.72]




SUBCHAPTER H – MEDICAL DEVICES



15

PART 820–QUALITY SYSTEM REGULATION

Subpart G–Production and Process Controls

Sec. 820.72 Inspection, measuring, and test equipment.

(a) Control of inspection, measuring, and test equipment. Eachmanufacturer shall ensure that all inspection, measuring, and

test equipment, including mechanical, automated, or electronic

inspection and test equipment, is suitable for its intended purposes

and is capable of producing valid results. Each manufacturer shall

establish and maintain procedures to ensure that equipment is

routinely calibrated, inspected, checked, and maintained. The

procedures shall include provisions for handling, preservation,

and storage of equipment, so that its accuracy and f itness for use

are maintained. These activities shall be documented.

(b) Calibration. Calibration procedures shall include specific directionsand limits for accuracy and precision. When accuracy and precision

limits are not met, there shall be provisions for remedial action to

reestablish the limits and to evaluate whether there was any adverse

effect on the device’s quality. These activities shall be documented.

(1) Calibration standards. Calibration standards used for

inspection, measuring, and test equipment shall be traceable to

national or international standards. If national or international

standards are not practical or available, the manufacturer shall

use an independent reproducible standard. If no applicable

standard exists, the manufacturer shall establish and maintain

an in-house standard.

(2) Calibration records. The equipment identification, calibration

dates, the individual performing each calibration, and the

next calibration date shall be documented. These records shall

be displayed on or near each piece of equipment or shall be

readily available to the personnel using such equipment and

to the individuals responsible for calibrating the equipment.



16

[Code of Federal Regulations]

[Title 21, Volume 4]

[Revised as of April 1, 2012]

[CITE: 21CFR211]

TITLE 21 – FOOD AND DRUGSCHAPTER I – FOOD AND DRUG ADMINISTRATION


SUBCHAPTER C – DRUGS: GENERAL

PART 211

CURRENT GOOD MANUFACTURING PRACTICE FOR

FINISHED PHARMACEUTICALS

Subpart D – Equipment

Sec. 211.68 Automatic, mechanical, and electronic equipment.

(a) Automatic, mechanical, or electronic equipment or other type

of equipment, including computers, or related systems that wi

perform a function satisfactorily, may be used in the manufacture

processing, packing, and holding of a drug product. If suc

equipment is so used, it shall be routinely calibrated, inspected, o

checked according to a written program designed to assure prope

performance. Written records of those calibration checks an

inspections shall be maintained.

Sec. 211.160 General requirements.

(b) Laboratory controls shall include the establishment of scientificall

sound and appropriate specifications, standards, sampling plan

and test procedures designed to assure that components, dru

product containers, closures, in-process materials, labeling, an

drug products conform to appropriate standards of identity

strength, quality, and purity. Laboratory controls shall include

(1) Determination of conformity to applicable writte

specifications for the acceptance of each lot within eac

shipment of components, drug product containers, closure



17

and labeling used in the manufacture, processing, packing,

or holding of drug products. The specifications shall include

a description of the sampling and testing procedures used.

Samples shall be representative and adequately identified.

Such procedures shall also require appropriate retesting of any

component, drug product container, or closure that is subjectto deterioration.

(2) Determination of conformance to written specifications and a

description of sampling and testing procedures for in-process

materials. Such samples shall be representative and properly

identified.

(3) Determination of conformance to written descriptions of

sampling procedures and appropriate specifications for drug

products. Such samples shall be representative and properly

identified.

(4) The calibration of instruments, apparatus, gauges, and

recording devices at suitable intervals in accordance with an

established written program containing specific directions,

schedules, limits for accuracy and precision, and provisions for

remedial action in the event accuracy and/or precision limits

are not met. Instruments, apparatus, gauges, and recording

devices not meeting established specifications shall not be

used.

[43 FR 45077, Sept. 29, 1978, as amended at 73 FR 51932,

Sept. 8, 2008]

Sec. 211.194 Laboratory records.

(d) Complete records shall be maintained of the periodic calibration

of laboratory instruments, apparatus, gauges, and recording

devices required by 211.160(b)(4).



18




SUBCHAPTER A – GENERAL

PART 11ELECTRONIC RECORDS; ELECTRONIC SIGNATURES

Subpart A – General Provisions

Sec. 11.1 Scope.

(a) The regulations in this part set forth the criteria under whic

the agency considers electronic records, electronic signature

and handwritten signatures executed to electronic records to b

trustworthy, reliable, and generally equivalent to paper record

and handwritten signatures executed on paper.

(b) This part applies to records in electronic form that are created

modified, maintained, archived, retrieved, or transmitted, unde

any records requirements set forth in agency regulations. Thi

part also applies to electronic records submitted to the agenc

under requirements of the Federal Food, Drug, and Cosmetic Ac

and the Public Health Service Act, even if such records are no

specifically identified in agency regulations. However, this par

does not apply to paper records that are, or have been, transmitte

by electronic means.

(c) Where electronic signatures and their associated electronic record

meet the requirements of this part, the agency will conside

the electronic signatures to be equivalent to full handwritte

signatures, initials, and other general signings as required b

agency regulations, unless specifically excepted by regulation(

effective on or after August 20, 1997.

(d) Electronic records that meet the requirements of this part may b

used in lieu of paper records, in accordance with 11.2, unless pape

records are specifically required.



19

(e) Computer systems (including hardware and software), controls, and

attendant documentation maintained under this part shall be readily

available for, and subject to, FDA inspection.

(f ) This part does not apply to records required to be established or

maintained by 1.326 through 1.368 of this chapter. Records thatsatisfy the requirements of part 1, subpart J of this chapter, but that

also are required under other applicable statutory provisions or

regulations, remain subject to this part.

[62 FR 13464, Mar. 20, 1997, as amended at 69 FR 71655,

Dec. 9, 2004]

Sec. 11.2 Implementation.

(a) For records required to be maintained but not submitted to the

agency, persons may use electronic records in lieu of paper recordsor electronic signatures in lieu of traditional signatures, in whole or

in part, provided that the requirements of this part are met.

(b) For records submitted to the agency, persons may use electronic

records in lieu of paper records or electronic signatures in lieu of

traditional signatures, in whole or in part, provided that:

(1) The requirements of this part are met; and

(2) The document or parts of a document to be submitted have been

identified in public docket No. 92S-0251 as being the type of

submission the agency accepts in electronic form. This docket

will identify specifically what types of documents or parts of

documents are acceptable for submission in electronic form

without paper records and the agency receiving unit(s) (e.g.,

specific center, office, division, branch) to which such submissions

may be made. Documents to agency receiving unit(s) not specified

in the public docket will not be considered as official if they are

submitted in electronic form; paper forms of such documents

will be considered as off icial and must accompany any electronic

records. Persons are expected to consult with the intended agency

receiving unit for details on how (e.g., method of transmission,

media, file formats, and technical protocols) and whether to

proceed with the electronic submission.



20

TITLE 21--FOOD AND DRUGS

CHAPTER I--FOOD AND DRUG ADMINISTRATION


SUBCHAPTER A--GENERAL

PART 11ELECTRONIC RECORDS; ELECTRONIC SIGNATURES

Subpart C – Electronic Signatures

Sec. 11.100 General requirements.

(a) Each electronic signature shall be unique to one individual an

shall not be reused by, or reassigned to, anyone else.

(b) Before an organization establishes, assigns, certif ies, or otherwis

sanctions an individual`s electronic signature, or any element osuch electronic signature, the organization shall verify the identit

of the individual.

(c) Persons using electronic signatures shall, prior to or at the tim

of such use, certify to the agency that the electronic signature

in their system, used on or after August 20, 1997, are intende

to be the legally binding equivalent of traditional handwritte

signatures.

(1) The certification shall be submitted in paper form and signe

with a traditional handwritten signature, to the Office o

Regional Operations (HFC-100), 12420 Parklawn Drive, RM

3007 Rockville, MD 20857.

(2) Persons using electronic signatures shall, upon agency reques

provide additional certification or testimony that a specifi

electronic signature is the legally binding equivalent of th

signer`s handwritten signature.



21

Calibration requirements according to the European Medicines

Agency (EMA)

Following are examples of some of the regulatory requirements of

the EMA, and what they say about calibration and what must be

accomplished to meet the GMPs.

Eudralex Volume 4

Chapter 3: Premises and Equipment

Equipment

3.41 Measuring, weighing, recording and control equipment should be

calibrated and checked at defined intervals by appropriate methods.

Adequate records of such tests should be maintained.

Chapter 4: Documentation

Manufacturing Formula and Processing Instructions

Approved, written Manufacturing Formula and Processing

Instructions should exist for each product and batch size to be

manufactured.

4.18 The Processing Instructions should include:

a) A statement of the processing location and the principal equipment

to be used; b) The methods, or reference to the methods, to be used for

preparing the critical equipment (e.g. cleaning, assembling, calibrating,

sterilising); c) Checks that the equipment and work station are clear

of previous products, documents or materials not required for the

planned process, and that equipment is clean and suitable for use; d)

Detailed stepwise processing instructions [e.g. checks on materials,

pre-treatments, sequence for adding materials, critical process

parameters (time, temp etc)]; e) The instructions for any in-process

controls with their limits; f) Where necessary, the requirements for

bulk storage of the products; including the container, labeling and

special storage conditions where applicable; g) Any special precautions

to be observed.



22

Procedures and records

Other

4.29 There should be written policies, procedures, protocols, repor

and the associated records of actions taken or conclusions reachedwhere appropriate, for the following examples:

• Validation and qualification of processes, equipment and systems

• Equipment assembly and calibration;

• Technology transfer;

• Maintenance, cleaning and sanitation;

• Personnel matters including signature lists, training in GMP and

technical matters, clothing and hygiene and verification of the

effectiveness of training.

• Environmental monitoring;

• Pest control;• Complaints;

• Recalls;

• Returns;

• Change control;

• Investigations into deviations and non-conformances;

• Internal quality/GMP compliance audits;

• Summaries of records where appropriate

(e.g. product quality review);

• Supplier audits.

4.31 Logbooks should be kept for major or critical analytical testing

production equipment, and areas where product has been processed

They should be used to record in chronological order, as appropriat

any use of the area, equipment/method, calibrations, maintenanc

cleaning or repair operations, including the dates and identity o

people who carried these operations out.



23

Chapter 6 Quality Control

Good Quality Control Laboratory Practice

Documentation

6.7 Laboratory documentation should follow the principles given

in Chapter 4. An important part of this documentation deals with

Quality Control and the following details should be readily available

to the Quality Control Department:

• specifications;

• sampling procedures;

• testing procedures and records (including analytical worksheets and/

or laboratory notebooks);

• analytical reports and/or certificates;

• data from environmental monitoring, where required;• validation records of test methods, where applicable;

• procedures for and records of the calibration of instruments and

maintenance of equipment.

Annex 15 to the EU Guide to Good Manufacturing Practice

Title: Qualification and validation

QUALIFICATION

Installation qualification

11. Installation qualification (IQ ) should be performed on new or

modified facilities, systems and equipment.

12. IQ should include, but not be limited to the following:

(a) installation of equipment, piping, services and instrumentation

checked to current engineering drawings and specifications;

(b) icollection and collation of supplier operating and working

instructions and maintenance requirements;

(c) icalibration requirements;

(d) verification of materials of construction.



24

Operational qualification

15. The completion of a successful Operational qualificatio

should allow the finalisation of calibration, operating and cleanin

procedures, operator training and preventative maintenanc

requirements. It should permit a formal “release” of the facilitiesystems and equipment.

Qualification of established (in-use) facilities, systems and equipmen

19. Evidence should be available to support and verify the operatin

parameters and limits for the critical variables of the operatin

equipment. Additionally, the calibration, cleaning, preventativ

maintenance, operating procedures and operator training procedure

and records should be documented.

PROCESS VALIDATION

Prospective validation

24. Prospective validation should include, but not be limited to th

following:

(a) short description of the process;

(b) summary of the critical processing steps to be investigated;

(c) list of the equipment/facilities to be used (including measuring

monitoring/recording equipment) together with its calibratio

status

(d) finished product specifications for release;

(e) list of analytical methods, as appropriate;

(f ) proposed in-process controls with acceptance criteria;

(g) additional testing to be carried out, with acceptance criteria an

analytical validation, as appropriate;

(h) sampling plan;

(i) methods for recording and evaluating results

(j) functions and responsibilities;

(k) proposed timetable.



25

EU GMP Annex 11

The EU GMP Annex 11 defines EU requirements for computerised

systems, and applies to all forms of computerised systems used as part

of GMP regulated activities.

Main page for the EudraLex - Volume 4 Good manufacturing practice

(GMP) Guidelines:

http://ec.europa.eu/health/documents/eudralex/vol-4/index_en.htm

PDF of Annex 11:

http://ec.europa.eu/health/files/eudralex/vol-4/annex11_01-2011_

en.pdf

EUROPEAN COMMISSION

HEALTH AND CONSUMERS DIRECTORATE-GENERAL

Public Health and Risk Assessment

Pharmaceuticals

Brussels,

SANCO/C8/AM/sl/ares(2010)1064599

EudraLex

The Rules Governing Medicinal Products in the European UnionVolume 4

Good Manufacturing Practice

Medicinal Products for Human and Veterinary Use

Annex 11: Computerised Systems

Legal basis for publishing the detailed guidelines: Article 47 of Directive

2001/83/EC on the Community code relating to medicinal products

for human use and Article 51 of Directive 2001/82/EC on the

Community code relating to veterinary medicinal products. This

document provides guidance for the interpretation of the principles



26

and guidelines of good manufacturing practice (GMP) for medicina

products as laid down in Directive 2003/94/EC for medicinal produc

for human use and Directive 91/412/EEC for veterinary use. Status

the document: revision 1

Reasons for changes: the Annex has been revised in response to thincreased use of computerised systems and the increased complexit

of these systems. Consequential amendments are also proposed fo

Chapter 4 of the GMP Guide.

Deadline for coming into operation: 30 June 2011

Commission Européenne, B-1049 Bruxelles / Europese Commissie

B-1049 Brussel - Belgium

Telephone: (32-2) 299 11 11

Principle

This annex applies to all forms of computerised systems used a

part of a GMP regulated activities. A computerised system is a se

of software and hardware components which together fulfill certai

functionalities.

The application should be validated; IT infrastructure should b

qualified.

Where a computerised system replaces a manual operation, ther

should be no resultant decrease in product quality, process control o

quality assurance. There should be no increase in the overall risk o

the process.

PIC/S

The abbreviation PIC/S describes both the Pharmaceutical Inspectio

Convention (PIC) and the Pharmaceutical Inspection Co-operatio

Scheme (PIC Scheme) which operate together. It aims to promot

harmonisation of global regulations for the pharmaceutical industry

Further information can be found at the PIC/S Web site (http://www

picscheme.org/.).



27

GAMP®

GAMP® is a Community of Practice (COP) of the International

Society for Pharmaceutical Engineering (ISPE). The GAMP® COP

aims to provide guidance and understanding concerning GxP

computerized systems. COPs provide networking opportunitiesfor people interested in similar topics. The GAMP® COP organizes

discussion forums for its members and ISPE organises GAMP® related

training courses and educational seminars.

GAMP® itself was founded in 1991 in the United Kingdom to

deal with the evolving FDA expectations for Good Manufacturing

Practice (GMP) compliance of manufacturing and related systems.

Since 1994, the organization entered into a partnership with the ISPE

and published its first GAMP® guidelines.

Three regional Steering Committees, GAMP® Japan, GAMP®

Europe, and GAMP® Americas support the GAMP® Council which

oversee the operation of the COP and is the main link to ISPE.Several local GAMP® COPs, such as GAMP® Americas, GAMP®

Nordic, GAMP® DACH (Germany, Austria, Switzerland), GAMP®

Francophone, GAMP® Italiano and GAMP® Japan, produce technical

content and translate ISPE technical documents. They also bring the

GAMP® community closer to its members, in collaboration with

ISPE’s local Aff iliates in these regions.

The most well known GAMP® publication is GAMP ® 5 A Risk-

Based Approach to GxP Computerized Systems. This is the latest major

revision and was released in January 2008. There is also a series of

related GAMP® guidance on specific topics, including:

• GAMP® Good Practice Guide: A Risk-Based Approach to

Calibration Management (Second Edition)

• GAMP® Good Practice Guide: A Risk-Based Approach to GxP

Compliant Laboratory Computerized Systems (Second Edition)

• GAMP® Good Practice Guide: A Risk-Based Approach to GxP

Process Control Systems (Second Edition)

• GAMP® Good Practice Guide: A Risk-Based Approach to Operation

of GxP Computerized Systems - A Companion Volume to GAMP® 5

• GAMP® Good Practice Guide: Electronic Data Archiving

• GAMP® Good Practice Guide: Global Information Systems Control

and Compliance



28

• GAMP® Good Practice Guide: IT Infrastructure Control an

Compliance

• GAMP® Good Practice Guide: Legacy Systems

The GAMP® Good Practice Guide: A Risk-Based Approach t

Calibration Management (second edition) was developed by ISPEGAMP® COP Calibration Special Interest Group (SIG) in conjunctio

with representatives from the pharmaceutical industry and input from

regulatory agencies. The Guide describes the principles of calibratio

and presents guidance in setting up a calibration management system

providing a structured approach to instrument risk assessmen

calibration program management, documentation, and correctiv

actions vital to regulatory compliance. The second edition of the guid

has been significantly updated to address the change in regulator

expectations and in associated industry guidance documents. Th

scope now includes related industries, laboratory, and analytica

instrumentation. A set of associated attachments are also availablthrough the ISPE website.

ISO 9001:2008

Basically, this is what is required according to ISO 9001:2008

7.6 CONTROL MONITORING AND MEASURING

EQUIPMENT

• Identify your organization’s monitoring and measuring need

and requirements (if your test instrument makes a quantitativ

measurement, it requires periodic calibration); and select tes

equipment that can meet those monitoring and measuring need

and requirements.

• Establish monitoring and measuring processes (calibratio

procedures and calibration record templates for recording you

calibration results).

• Calibrate your monitoring and measuring equipment using a perio

schedule to ensure that results are valid (you should also perform

a yearly evaluation of your calibration results to see if there is

need to increase or decrease your calibration intervals on calibrate

test equipment). All calibrations must be traceable to a national o

international standard or artifact.



29

• Protect your monitoring and measuring equipment (this includes

during handling, preservation, storage, transportation, and shipping

of all test instruments – to include your customer’s items, and your

calibration standards).

• Confirm that monitoring and measuring software is capable of

doing the job you want it to do (your software needs to be validatedbefore being used, and when required, your test instruments may

need to be qualified prior to use).

• Evaluate the validity of previous measurements whenever you

discover that your measuring or monitoring equipment is out-of-

calibration (as stated in the FDA regulations, “When accuracy and

precision limits are not met, there shall be provisions for remedial

action to reestablish the limits and to evaluate whether there was

any adverse effect on the device’s quality”; this is just as applicable

when dealing with ISO as with any other standard or regulation;

especially when the out of tolerance item is a calibration standard,

and may have affected numerous items of test equipment over aperiod of time).

ISO 17025

ISO 17025 – General requirements for the competence of testing and

calibration laboratories. According to ISO 17025, this standard is

applicable to all organizations performing tests and/or calibrations.

These include first-, second-, and third-party laboratories, and

laboratories where testing and/or calibration forms part of inspection

and product certifications. Please keep in mind that if your calibration

function and/or metrology department fall under the requirements

of your company, rather it be for compliance to an ISO standard

(ISO 9001:2008 or ISO 13485) or an FDA requirement (cGMP, QSR,

etc.), then you do not have any obligation to meet the ISO 17025

standard. You already fall under a quality system that takes care of

your calibration requirements.

ANSI/NCSL Z540.3-2006

ANSI/NCSL Z540.3-2006 – American National Standard for

Calibration-Requirements for the Calibration of Measuring and Test

Equipment.



30

The objective of this National Standard is to establish the technica

requirements for the calibration of measuring and test equipmen

This is done through the use of a system of functional component

Collectively, these components are used to manage and assure tha

the accuracy and reliability of the measuring and test equipment arin accordance with identified performance requirements.

In implementing its objective, this National Standard describes th

technical requirements for establishing and maintaining:

• the acceptability of the performance of measuring and tes

equipment;

• the suitability of a calibration for its intended application;

• the compatibility of measurements with the National Measuremen

System; and

• the traceability of measurement results to the International System

of Units (SI).

In the development of this National Standard attention has beegiven to:

• expressing the technical requirements for a calibration system

supporting both government and industry needs;

• applying best practices and experience with related nationa

international, industry, and government standards; and

• balancing the needs and interests of all stakeholders.

In addition, this National Standard includes and updates the relevan

calibration system requirements for measuring and test equipmen

described by the previous standards, Part 11 of ANSI/NCSL Z540.

(R2002) and Military Standard 45662A.

This National Standard is written for both Supplier and Custome

each term being interpreted in the broadest sense. The “Supplier ma

be a producer, distributor, vendor, or a provider of a product, service

or information. The “Customer” may be a consumer, client, enduse

retailer, or purchaser that receives a product or service.

Reference to this National Standard may be made by:

• customers when specifying products (including services) required

• suppliers when specifying products offered;

• legislative or regulatory bodies;

• agencies or organizations as a contractual condition fo

procurement; and

• assessment organizations in the audit, certification, and othe

evaluations of calibration systems and their components.



31

This National Standard is specific to calibration systems. A

calibration system operating in full compliance with this National

Standard promotes confidence and facilitates management of the risks

associated with measurements, tests, and calibrations.8

Equipment intended for use in potentially explosive atmospheres

(ATEX)

What are ATEX and IECEx?

ATEX (“ATmosphères EXplosibles”, explosive atmospheres in French)

is a standard set in the European Union for explosion protection in the

industry. ATEX 95 equipment directive 94/9/EC concerns equipment

intended for use in potentially explosive areas. Companies in the

EU where the risk of explosion is evident must also use the ATEX

guidelines for protecting the employees. In addition, the ATEX rulesare obligatory for electronic and electrical equipment that will be used

in potentially explosive atmospheres sold in the EU as of July 1, 2003.

IEC (International Electrotechnical Commission) is a nonprofit

international standards organization that prepares and publishes

International Standards for electrical technologies. The IEC TC/31

technical committee deals with the standards related to equipment for

explosive atmospheres. IECEx is an international scheme for certifying

procedures for equipment designed for use in explosive atmospheres.

The objective of the IECEx Scheme is to facilitate international trade

in equipment and services for use in explosive atmospheres, while

maintaining the required level of safety.

In most cases, test equipment that is required to be operated in

an explosive environment would be qualified and installed by the

company’s facility services department and not the calibration

personnel. One must also keep in mind that there would be two

different avenues for the calibration of those pieces of test equipment:

on-site and off-site. If the test instrument that is used in an explosive

environment must be calibrated on-site (in the explosive environment),

then all the standards used for that calibration must also comply

with explosive environment directives. However, if it were possible

to remove the test equipment from the explosive environment when

due for their period calibration, then there would be no requirement

for the standards used for their calibration to meet the explosive



32

environment directives, saving money on expensive standards an

possibly expensive training of calibration personnel in order for them

to work in those conditions.

Having said that, there may be a need for the calibration personn

to be aware of the ATEX regulations. An informative website fo

information on ATEX can be found by typing in the following linkhttp://ec.europa.eu/enterprise/atex/indexinfor.htm. Several language

are available for retrieving the information.

Another informative website is the International Electrotechnic

Commission Scheme for Certification to Standards Relating t

Equipment for use in Explosive Atmospheres (IECEx Scheme). Th

link is: http://www.iecex.com/guides.htm.

1. Bucher, Jay L. 2007. The Quality Calibration Handbook.

Milwaukee: ASQ Quality Press.

2. The Story of the Egyptian Cubit. http://www.ncsli.org/misc/

cubit.cfm. (18 October, 2008)3. 21CFR Part 211.68, 211.160: http://www.accessdata.fda.gov/

scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=211/

(5 July, 2012)

4. 21CFR Part 11. http://www.fda.gov/downloads/

RegulatoryInformation/Guidances/ucm125125.pdf (5 July, 2012

and http://www.fda.gov/RegulatoryInformation/Guidances/

ucm125067.htm?utm_campaign=Google2&utm_

source=fdaSearch&utm_medium=website&utm_term=21 CFR

part 11&utm_content=3

5. GAMP. http://en.wikipedia.org/wiki/Good_Automated_

Manufacturing_Practice (5 July, 2012)

6. NCSL International. 2006. ANSI/NCSL Z540.3-2006.

Boulder, CO.



34



35

R &D departments are tasked with coming up with the answers

to many problems; the cure for cancer is one of them. Let’s

imagine that the Acme Biotech Co. has found the cure for

cancer. Their R&D section sends the formula to their operations &

manufacturing division. The cure cannot be replicated with consistentresults. They are not using calibrated test instruments in the company.

Measurements made by R&D are different than those made by the

operations section. If all test equipment were calibrated to a traceable

standard, then repeatable results would ensure that what’s made in one

part of the company is also repeated in another part of the company.

The company loses time, money, their reputation, and possibly the

ability to stay in business simply because they do not use calibrated

test equipment. A fairy tale? Not hardly. This scenario is repeated

every day throughout the world.

Without calibration, or by using incorrect calibrations, all of us pay

more at the gas pump, for food weighed incorrectly at the checkout

counter, and for manufactured goods that do not meet their stated

specifications. Incorrect amounts of ingredients in your prescription

and over-the-counter (OTC) drugs can cost more, or even cause

illness or death. Because of poor or incorrect calibration, criminals

are either not convicted or are released on bad evidence. Crime labs

cannot identify the remains of victims or wrongly identify victims

in the case of mass graves. Airliners fly into mountaintops and off

the ends of runways because they don’t know their altitude and/or

speed. Babies are not correctly weighed at birth. The amount of drugs

confiscated in a raid determines whether the offense is a misdemeanor

or a felony; which weight is correct? As one can see, having the correct

measurements throughout any and all industries is critical to national

and international trade and commerce.

A basic quality

calibration program



36

The bottom line is this – all test equipment that make a quantitativ

measurement require periodic calibration. It is as simple as tha

However, before we go any further, we need to clarify two definition

that are critical to this subject – calibration and traceability.

By definition:

Calibration is a comparison of two measurement devices or system

one of known uncertainty (your standard) and one of unknow

uncertainty (your test equipment or instrument).

Traceability is the property of the result of a measurement or the valu

of a standard whereby it can be related to stated references, usuall

national or international standards, through an unbroken chain o

calibrations all having stated uncertainties.

The calibration of any piece of equipment or system is simpl

a comparison between the standard being used (with its knowuncertainty), and the unit under test (UUT) or test instrument tha

is being calibrated (the uncertainty is unknown, and that is why it

being calibrated). It does not make any difference if you adjust, align o

repair the item, nor if you cannot adjust or align it. The comparison t

a standard that is more accurate, no matter the circumstances is calle

calibration. Many people are under the misconception that an item

must be adjusted or aligned in order to be calibrated. Nothing coul

be further from the truth.

Before we can get any deeper into what traceability is, we shoul

explain two different traceability pyramids. When we talk abou

traceability to a national or international standard, the ‘everyda

calibration technician’ is usually situated close to the bottom of th

pyramid, so a graphic illustration of these pyramids is important.

The two examples in figures 1 and 2 are similar, but differ dependin

on where you are in the chain, or certain parts of the world.

There are basically two ways to maintain traceability durin

calibration – the use of an uncertainty budget (performing uncertaint

calculations for each measurement); and using a test uncertainty rati

(TUR) of ≥ 4:1. First, let’s discuss the use of uncertainty budgets.

According to the European cooperation for Accreditation o

Laboratories, publication reference (EAL-G12) Traceability of Measurin

and Test Equipment to National Standards; the purpose of which is t

give guidance on the calibration and maintenance of measurin



37

equipment in meeting the requirements of the ISO 9000 series of

standards for quality systems, and the EN 45001 standard for the

operation of testing laboratories; paragraphs 4 and 5 are very specific

in their requirements:

4 Why are calibrations and traceability necessary?

4.1 Traceability of measuring and test equipment to national standards

by means of calibration is necessitated by the growing national and

international demand that manufactured parts be interchangeable;

supplier firms that make products, and customers who install them

with other parts, must measure with the ‘same measure’.

BIPM

Reference standards

General purpose calibration labs

(inside a company)

NMIs

Working metrology labs

User’s test equipment

Figure 1

SI units

Secondary standards

Working standards

Primary stds.

Reference standards

User’s test equipment

Figure 2

Note: NMI = National Metrology Institute



38

4.2 There are legal as well as technical reasons for traceability o

measurement. Relevant laws and regulations have to be complie

with just as much as the contractual provisions agreed with th

purchaser of the product (guarantee of product quality) and th

obligation to put into circulation only products whose safety,

they are used properly, is not affected by defects.Note: If binding requirements for the accuracy of measurin

and test equipment have been stipulated, failure to meet thes

requirements means the absence of a warranted quality wit

considerable consequent liability.

4.3 If it becomes necessary to prove absence of liability, the produce

must be able to demonstrate, by reference to a systematic and full

documented system, that adequate measuring and test equipmen

was chosen, was in proper working order and was used correctl

for controlling a product.

4.4 There are similar technical and legal reasons why calibration an

testing laboratory operators should have consistent control omeasuring and test equipment in the manner described.

5 Elements of traceability

5.1 Traceability is characterised by a number of essential elements:

(a) an unbroken chain of comparisons going back to a standar

acceptable to the parties, usually a national or internationa

standard;

(b) measurement uncertainty; the measurement uncertaint

for each step in the traceability chain must be calculate

according to agreed methods and must be stated so that a

overall uncertainty for the whole chain may be calculated;

(c) documentation; each step in the chain must be performe

according to documented and generally acknowledge

procedures; the results must equally be documented;

(d) competence; the laboratories or bodies performing one o

more steps in the chain must supply evidence for their technica

competence, e.g. by demonstrating that they are accredited;

(e) reference to SI units; the chain of comparisons must end

primary standards for the realization of the SI units;

(f) re-calibrations; calibrations must be repeated at appropriat

intervals; the length of these intervals will depend on a numbe

of variables, e.g. uncertainty required, frequency of use, way o

use, stability of the equipment.



39

5.2 In many fields, reference materials take the position of physical

reference standards. It is equally important that such reference

materials are traceable to relevant SI units. Certification of

reference materials is a method that is often used to demonstrate

traceability to SI units.1

The other document that goes hand-in-hand with this is EA 4/02,

Expression of the Uncertainty of Measurement in Calibration. The

purpose of this document is to harmonise evaluation of uncertainty

of measurement within EA, to set up, in addition to the general

requirements of EAL-R1, the specific demands in reporting

uncertainty of measurement on calibration certificates issued by

accredited laboratories and to assist accreditation bodies with a

coherent assignment of best measurement capability to calibration

laboratories accredited by them. As the rules laid down in this

document are in compliance with the recommendations of the Guide

to the Expression of Uncertainty in Measurement, published byseven international organisations concerned with standardisation and

metrology, the implementation of EA-4/02 will also foster the global

acceptance of European results of measurement.2

By understanding and following both of these documents, a

calibration function can easily maintain traceable calibrations for

the requirements demanded by their customers and the standard or

regulation that their company needs to meet.

To maintain traceability, without using uncertainty budgets or

calculations, you must ensure your standards are at least four times

(4:1) more accurate than the test equipment being calibrated. Where

does this ratio of four to one (4:1) come from? It comes from the

American National Standard for Calibration – (ANSI/NCSL Z540.3-

2006) which states: “Where calibrations provide for verification that

measurement quantities are within specified tolerances…Where it is not

practical to estimate this probability, the TUR shall be equal to or greater

than 4:1.”

So, if a TUR of equal to or greater than 4:1 is maintained, then

traceability is assured. Keep in mind that a TUR of 4:1 somewhere

along the chain of calibrations may not have been feasible, and

uncertainty calculations were performed and their uncertainty stated

on the certificate of calibration. This is correct and acceptable. In

most circumstances, where the need to maintain a TUR of 4:1 comes

into play, is at the company or shop level, where the customer’s test



40

equipment is usually used for production or manufacturing purpose

only.

So how does calibration and traceability fit into the big picture

What does the big picture look like? Why do you need a qualit

calibration program?

You need to establish a quality calibration program to ensure thaall operations throughout the metrology department occur in a stab

manner. The effective operation of such a system will hopefully resu

in stable processes and, therefore, in a consistent output from thos

processes. Once stability and consistency are achieved, it is possib

to initiate process improvements. This is applicable in every phase o

a production and/or manufacturing program. But especially true in

metrology department.3

Let’s take for example a calibration program that has six calibratio

technicians on staff. Four of them work in another facility calibratin

the same types of equipment as the other two. However, the other tw

have far more experience and through no fault of their own do not usthe calibration procedures that are required by their quality system

They have calibrated the same items for several years and feel there

nothing new to learn. One of the four calibration technicians (wh

are always following the calibration procedures) finds there is a fas

more economical way to perform a specific calibration. They submit

change proposal for the calibration procedure and everyone is briefe

and trained on the new technique. The four calibration technician

that have been following the calibration procedure improve the

production and save the company money. The two ‘old timers’ have

reduction in their production and actually cost the company money.

everyone was using the calibration procedures like they were suppose

to, then this would not have happened.

Process improvements cannot take place across the department

everyone is not doing the job the same way each and every time the

perform a calibration.

We are not ignorant enough to believe that when calibratio

technicians have performed a particular calibration hundreds or eve

thousands of times that they are going to follow calibration procedure

word for word. Of course not. But they must have their calibratio

procedure on hand each time they are performing the calibration.

a change has been made to that procedure, the calibration technicia

must be trained on the change before they can perform the calibration

and the appropriate documentation completed to show that trainin



41

was accomplished and signed off. When the proper training is not

documented and signed off by the trainer and trainee, then it is the

same as if the training never happened.

What is a quality calibration program?A quality calibration program consists of several broad items referred

to in the Quality System Regulation (QSR) from the Food and Drug

Administration (FDA). These items are also referred to by other

standards (ISO 9000, etc.) and regulations throughout most industries

that regulate or monitor production and manufacturing of all types

of products. One of the most stringent requirements can be found in

the current Good Manufacturing Procedures (GMP).

The basic premise and foundation of a quality calibration program

is to “Say what you do, Do what you say, Record what you did, Check the

results, and Act on the difference”. Let’s break these down into simple

terms.

“Say what you do” means write in detail how to do your job. This

includes calibration procedures, work instructions and standard

operating procedures (SOPs).

“Do what you say” means follow the documented procedures or

instructions every time you calibrate, or perform a function that

follows specific written instructions.

“Record what you did” means that you must record the results of your

measurements and adjustments, including what your standard(s) read or

indicated both before and after any adjustments might be made.

“Check the results” means make certain the test equipment meets

the tolerances, accuracies, or upper/lower limits specif ied in your

procedures or instructions.

“Act on the difference” means if the test equipment is out of tolerance,

you’re required to inform the user/owner of the equipment because

they may have to re-evaluate manufactured goods, change a process,

or recall a product.3

“Say what you do” means write in detail how to do your job. This

includes calibration procedures, work instructions and SOPs. All

of your calibration procedures should be formatted the same as

other SOPs within your company. Here is an example of common

formatting for SOPs:



42

1. Procedures

2. Scope

3. Responsibilities

4. Definitions

5. Procedure

6. Related Procedures7. Forms and Records

8. Document History

After section 4. Definitions, you should have a table listing all of th

instruments or systems that would be calibrated by that procedure

along with their range and tolerances. After that you should have

list of the standards to be used to calibrate the items. This table shoul

also include the standard’s range and specifications. Then the actua

calibration procedure starts in section 5. Procedures.

Manufacturer’s manuals usually provide an alignment procedur

that can be used as a template for writing a calibration procedure. Theshould show what standards accomplish the calibration of a specif

range and/or function. A complete calibration must be performe

prior to any adjustment or alignment. An alignment procedure and

or preventive maintenance inspection (PMI) may be incorporate

into your SOP as long as it is separate from the actual calibratio

procedure.

There are, generally speaking, two types of calibration procedure

Generic: temperature gages and thermometers, pressure and vacuum

gages, pipettes, micrometers, power supplies and water baths.

Specific: spectrophotometers, thermal cyclers, and balances/scales.

Generic SOPs are written to show how to calibrate a large variet

of items in a general context. Specific SOPs are written to show step

by-step procedures for each different type of test instrument withi

a group of items. Possibly, the calibration form is designed to follow

specific steps (number wise); and removes doubt by the calibratio

technician on what data goes into which data f ield.

“Do what you say” means follow the documented procedures o

instructions every time you calibrate, or perform a function that follow

specific written instructions. This means following published calibratio

procedures every time you calibrate a piece of test equipment.

Have the latest edition of the procedure available for use by you

calibration technicians. Have a system in place for updating you



43

procedures. Train your technicians on the changes made to your

procedures every time the procedure is changed or improved – and

document the training.

What do you do when you need to make an improvement, or update

your calibration procedures and/or forms? A formal, written process

must be in place, to include:• Who can make changes

• Who is the final approval authority

• A revision tracking system

• A process for validating the changes

• An archiving system for old procedures

• Instructions for posting new/removal of old procedures

• A system for training on revisions

• A place to document that training was done

“Record what you did” means that you must record the results of your

measurements and adjustments, including what your standard(s) reador indicated both before and after any adjustments are made, and keep

your calibration records in a secure location. Certain requirements

must be documented in each calibration record. Of course there are

many ways to accomplish this, including:

• pen and paper

• “do-it-yourself” databases, e.g. Excel, Access

• calibration module of a computerized maintenance management

system (CMMS)

• calibration software specifically designed for that purpose

These include the identification of the test instrument with a unique

identification number, their part number and range/tolerance. The

location of where the test instrument can be found should also be on

the record. A history of each calibration and a traceability statement

or uncertainty budget must be included. The date of calibration, the

last time it was calibrated, and the next time it will be due calibration

should be on the form. There should be a place to show what the

standard read, as well as the test instrument’s ‘As Found’ and when

applicable ‘As Left’ readings.

The ‘As Found’ readings are what the test instrument read the first time

that a calibration is performed, prior to alignment, adjustment or repair.

The entire calibration is performed to see any part of the calibration

is out of tolerance. If an out-of-tolerance (OOT) condition is found,



44

record the reading (on the standard and the UUT) and continue wit

the rest of the calibration to the end of the calibration procedure. If on

were to stop at the point where an OOT is found, make an adjustmen

then proceed with the calibration, there is a good possibility that th

adjustment affected other ranges or parts of the calibration. This is wh

the entire calibration is performed prior to adjustment or alignment.There will be times when an instrument has a catastrophic failur

It just dies and cannot be calibrated. This should be noted in th

calibration record. Then, once the problem is found and repaired, a

‘As Found’ calibration is performed. The UUT is treated the same a

any OOT unit, but you would not have been able to collect the origin

“As Found’ readings.

“As Left” readings are taken after repair, alignment, or adjustmen

Not all UUTs would be considered OOT when “As Left’ reading

are taken. In some circumstances, it might be metrology departmen

policy to adjust an item if it is more than ½ beyond its in-toleranc

range, while still meeting its specifications. In this type of situationafter the UUT is adjusted to be as close to optimum as possible,

complete calibration is again performed, collecting the ‘As Lef

readings for the f inal calibration record. Another example would b

when preventive maintenance inspection is going to be performed o

an item. The calibration is performed, collecting the ‘As Found’ dat

Then the PMI is completed, and an ‘As Left’ set of data is collecte

If the item is found to be out-of-tolerance at that time, there woul

not be a problem since it was found to be in tolerance during the fir

calibration. It would be obvious that something happened during th

cleaning, alignment or adjustment and that after a final adjustmen

was completed to bring the unit back into tolerance, a final ‘As Lef

calibration would be performed.

The standard reading, from the working or reference standard you a

using to calibrate the UUT, will also be recorded on the calibration form

Usually, the standard is set at a predetermined output, and the UUT

read to see how much it deviates from the standard. This is a best practic

policy that has been in use in the metrology community since calibratio

started. However, there will be times when this is not possible.

One example when it would not be practical to set the standard an

take a reading is during the calibration of water baths. The water bat

is set to a predetermined temperature, and the temperature standard

used to record the actual reading. Compare this to the calibration

pressure gages where a pressure standard is set to a standard pressur



45

and the gage(s) under test are then read, and their pressures recorded on

the calibration record, and compared to the standard to see if they are

in or out of tolerance. In other case, just as the calibration of autoclaves,

they are set to complete a sterilization cycle and a temperature device

records all of the temperature readings throughout the cycle and the

readings are checked to see if the autoclave met its specifications. Thesame happens when calibrating thermometers. They, along with the

standard, are placed in a dry block and a particular temperature is

set. The UUT is compared to the reference after equilibration, and a

determination is made as to the in or out of tolerance of the UUT. As

can be seen by the above examples, it is not always possible to set the

standard and take a reading from the UUT.

Also on the calibration form should be an area to identify the

standard(s) that were used, along with their next calibration due

date(s), plus their specifications and range.

There should also be a place to identify which calibration procedure

was used, along with the procedure’s revision number. There must bea statement showing traceability to your NMI, or in the case of most

companies in the USA, to NIST, or to any artifact that was used as a

standard.

You should include any uncertainty budgets if used, or at least a

statement that a TUR of ≥ 4:1 was met.

List environment conditions when appropriate and show if they pass

or fail. According to NCSL International Calibration Control Systems

for the Biomedical and Pharmaceutical Industry – Recommended

Practice RP-6, paragraph 5.11: “The calibration environment need be

controlled only to the extent required by the most environmentally

sensitive measurement performed in the area.”4

According to ANSI/NCSL Z540.3-2006, paragraph 5.3.6 Influence

factors and conditions: “All factors and conditions of the calibration

area that adversely influence the calibration results shall be defined,

monitored, recorded, and mitigated to meet calibration process

requirements. Note: Influencing factors and conditions may include

temperature, humidity, vibration, electromagnetic interference, dust,

etc. Calibration shall be stopped when the adverse effects of the

influence factors ad conditions jeopardize the results of the calibration.”5

If the conditions within the area that calibrations are being performed

require monitoring according to the standard or requirements that must

be met, then a formal program must be in place for tracking those

conditions and reviewing the data. If this is the case, then there should

be a place in the calibration form for showing that those conditions were



46

either met, were not met, or are not applicable to that calibration.

You should indicate on the form if the calibration passed or failed

If the UUT had an out-of-tolerance condition, then there shoul

be a place to show what happened to the UUT, with the followin

possibilities as an example:

• The user/customer was notified and the UUT was adjusted

and meets specifications.

• The user/customer was notified and the UUT was given

a ‘limited calibration’ with their written approval.

• The user/customer was notified and the UUT was taken

out of service and tagged as unusable.

Notice that in each circumstance that the user/customer must b

notified of any and all OOTs. This is called for in all of the standard

and regulations. The user/customer, even if internal to the compan

performing the calibrations, must be informed if their test equipmendoes not meet their specifications.

There should be an area set aside in the calibration form for makin

comments or remarks. Enough space should be available for th

calibration technician to include information about the calibration

OOT conditions, what was accomplished if an OOT was found, etc

And finally, the calibration record must be signed and dated b

the technician performing the calibration. In some instances, th

calibration record requires a ‘second set of eyes’. This means that a

individual higher up the chain of command (supervisor, manage

QA inspector, etc.) must review the calibration record and also sig

and date that it has been reviewed, audited, or inspected before it

considered a completed record. If this is the case, there should be

place on the form for the final reviewer to sign and date.

What do you do if, after recording your results, you find that yo

have made an error, or transposed the wrong numbers, and want t

correct the error? For hard copy records, draw a single line throug

the entry, write the correct data, and then place your initials and dat

next to the data using black ink. Do not use white-out, or erase th

original data. For making corrections to electronic records (eRecords

use whatever tracking system the software uses; or make a duplica

record from scratch with the correct data and explain in the commen

block what happened, and date and sign accordingly.

There should be only one way to file your records, both hard cop



47

and eRecords – no matter which system you use, put it into your

written procedures.

An example for filing hard copy records:

• Each record is filed by its unique ID number

• Records are filed with the newest in the front• Records are filed within a specified time frame

An example for filing eRecords:

• Filed by ID number, calibration certificate number and calibration

date

• Placed on a secure drive that has regular backup

• eRecords are filed within a specified time frame

There are many different ways to manage your calibration data since

there are a variety of ways to collect that data. Hard copy records collected

during the calibration of test instruments have been discussed in detailalready. But the collection of data by electronic means, or through the

use of calibration software, process controllers, etc., should also be

considered. Is the system validated and instrumentation qualified prior

to use? If you are using any type of computerized system, validation of

that software is mandatory. How is the data collected and stored? Is it in

its native format or dumped into a spreadsheet for analysis? All of these

need to be considered to allow for review, analysis, and/or compilation

into your forms, and eventual storage.

The use of computerized data collection brings with it not only

increased productivity and savings in time and effort; but also new

problems in how to collect, manage, review and store the data. It

cannot be emphasized enough the criticality of validating your

software, data lines and storage systems when going entirely electronic

with your calibration records and data management.

“Check the results” means make certain the test equipment meets

the tolerances, accuracies, or upper/lower limits specif ied in your

procedures or instructions.

There are various ways to do this. Calibration forms should have the

range and their tolerances listed for each piece of test equipment being

calibrated. In some instances it is apparent what the tolerances will be

for the items being calibrated. In other cases it is not quite so apparent.



48

“Act on the difference” means if the test equipment is out of toleranc

you must inform the user because they may have to re-evaluat

manufactured goods, change a process or procedure, or recall produc

According to the FDA: “When accuracy and precision limits are not me

there shall be provisions for remedial action to reestablish the limits and t

evaluate whether there was any adverse effect on the device’s quality.”

You should have a written procedure in place that explains in detail

• What actions are to be taken by the calibration technician?

• What actions to be taken by the department supervisor and/o

manager?

• What actions to be taken by the responsible owner/user of th

OOT test equipment?

You should have an SOP that explains the responsibilities of th

calibration technician:

• Do they have additional form(s) to complete when OOTconditions are found?

• Do they require a ‘second set of eyes’ when/if an OOT is found

• Have they been trained and signed off that they know all th

proper procedures when an OOT has been found?

You should have an SOP that explains the responsibilities of th

supervisor/manager:

• Who notifies the customer – the technician, supervisor or

manager?

• Is a data base maintained on all OOT test equipment?

• Is the customer/user required to reply to the OOT notification

if so is there a time limit, and a paper trail for historical

reference?

After owner/user notification, is the calibration departmen

responsible for anything else?

• Is the final action by the owner/user sent back for filing o

archiving?

• Usually the department that generates an action item is responsib

for final archiving.

• Are there any databases that need to be updated; or uppe

management notification in case of ‘in action’?



49

Do you have a database of all OOT test equipment for various

activities?

• The database can be used for accessing yearly calibration interval

analysis.

• Access to OOT data can assist in determining reliability of test

equipment.• During an audit/inspection (both internal and external) access to

past OOT data should be easily available.

Here is a hypothetical example: from an historical perspective,

generally 85% of test equipment passes calibration.

• Among the 15% that are found to be OOT some will be due to

Start

End

‘As found’

test

Adjust

as needed

‘As Left’

test

Save

‘As found’

results

Save

‘As Left’

results

YES

NO

NO

YES

Adjustment

required?

Within

limits?

Typical calibration

process as shown

in a flow chart



50

operator error, bad standards, bad cables/accessories, poorly writte

calibration procedures, environmental conditions (vibration, etc.

• If a higher fail rate is noticed, before changing calibration interval

check that the proper specifications are being used.

Developing a world-class calibration program

A quality calibration program might be compared to an iceberg. Onl

about 10% can be easily seen by the casual observer. However, th

unseen portion is what keeps the iceberg afloat and stable in the ocean

The same can be said of a quality calibration program. The “Sa

what you do, Do what you say, Record what you did, Check the result

and Act on the difference” portion, along with traceability should b

apparent to an auditor or inspector. But the different parts that kee

a quality calibration program running eff iciently consist of elemen

from a continuous process improvement program, scheduling an

calibration management software, an effective training program, comprehensive calibration analysis program, correct and properl

used calibration and equipment labels, and a visible safety program

Without any one of these programs, a quality calibration program

would be impossible to maintain.

Having an effective calibration management program is usually th

difference between being proactive and reactive to performing you

routine calibrations. By knowing what is coming due calibration, yo

can schedule your technicians, standards, time and other resource

to the best advantage. This can be compared to the person who

trying to drain the swamp while fighting off the alligators. It is har

to keep your overdue calibrations at a minimum when all of your tim

is spent reacting to items that keep coming due without your prio

knowledge. Any calibration management program worth the mone

should have a few critical areas built into their basic program. Thos

include: a master inventory list, reverse traceability, the ability to se

a 30 day schedule of items coming due calibration, and the ability t

see all items that are currently overdue calibration. From a manageria

standpoint, the calibration management program should also be ab

to show calibrations and repairs by individual items, groups of item

by location/part number, items that are OOT, and other listings tha

help to manage your department. According to most standards an

regulations, any software program used must be validated prior t

implementation. This can be accomplished using the manufacturer



51

system, or by incorporating an in-house validation system. Either way,

your validation paperwork needs to be available for inspection during

audits and inspections.

A best practice among experienced calibration practitioners is the

calibration of like items, and using your scheduling software to also

perform calibrations in geographical areas or combining calibrationsin local areas. An example of this would be to calibrate all pressure

gages that were shown to be stored or used in a specific area, or f loor of

a building. This would be using your time to the best advantage. Also,

if calibrations were to be performed in a ‘clean room’ environment,

and the calibration technician is required to gown-up prior to entry

every time then go into the clean-room, then scheduling all of the

calibrations in that area could increase production and reduce down

time from multiple entries and exits.

Combining the calibration of like items and mixing and matching

items could reduce the task of mundane and boring calibrations. An

example would be to start all temperature calibrations (set water bathsup for their initial temperature readings), then perform several pipette

or balance calibrations, return to set another temperature in the water

baths (doing a few at a time), return to finish the pipette or balance

calibrations, then complete the water baths at their final setting. By not

having to stand around to wait for the water baths to equilibrate, you are

using your time more efficiently, increasing productivity, and keeping

the calibration technician involved and focused instead of bored.

Another critical yet often times misunderstood program is

calibration interval analysis. How often should each type of test

equipment be calibrated? Should the manufacturer’s recommended

interval be the determining factor? Or should the criticality of how the

test equipment is used in your particular production or manufacturing

line be the deciding vote? Your specif ic situation should be the driving

factor in deciding calibration interval analysis. Most manufacturers

recommend a 12 month calibration interval, depending on usage,

environment, handling, etc. A particular item used in a controlled

environment should be more reliable that one used in a harsher

situation, say outdoors in severe weather. Also, you must consider if the

test equipment is used to determine final product where specifications

are very tight, or used as an item that is coded as “No Calibration

Required” on a loading dock. Each situation should be considered

carefully so that they can be reviewed in the appropriate light.

Calibration interval analysis software can be purchased commercially



52

and used to evaluate your test equipment. Also, NCSL Internationa

has RP-1, Establishment & Adjustment of Calibration Intervals. Th

Recommended Practice (RP) is intended to provide a guide for th

establishment and adjustment of calibration intervals for equipmen

subject to periodic calibration. It provides information needed t

design, implement and manage calibration interval determinationadjustment and evaluation programs. Both management and technic

information are presented in this RP. Several methods of calibratio

interval analysis and adjustment are presented. The advantages an

disadvantages of each method are described and guidelines are give

to assist in selecting the best method for a requiring organization.

A company could also do their own analysis if they support a limite

number of items, or are on a tight budget and are willing to do the

own computations. Here is an example.

• For each type of equipment, collect data over a one year perio

on: number of calibrations and number of items OOT• Take the number of calibrations minus the number of OOT

divide result by the number of calibrations, then take the resu

times 100 for the pass rate

• Make a risk assessment of each item for your company’s needs; se

a cut off for increasing or decreasing calibration intervals

• Consider increasing a calibration interval if the pass rate ≥ 95%

(by ½ up to double the current calibration interval)

• Consider decreasing a calibration interval if the pass rate ≤ 85%

(by ¾ to ½ of the current calibration interval)

No matter which route you take for calibration interval analys

– ensure you are on the cutting-edge – not on the ragged-edge b

extending your intervals too fast without solid data; recalls can b

very expensive, in time and money, and to your company’s reputation

The cost and risk of not calibrating

Are there costs and/or risks associated to not calibrating your tes

equipment? This is a double edged sword. On one side we have th

requirement of standards and regulations that govern various companie

industries and even countries. Not only is calibration a requirement, bu

one of the foundations for any quality system in the 21st century. It isn

a question of do you have a quality calibration program in place, bu



53

does it comply with all the requirements of the appropriate standard or

regulation to which your company must conform?

The other side of the double edged sword is having a calibration

program in place without any type of quality, traceability or

documentation. This would equate to not having any type of

calibration program at all. If a manufacturer produces any type ofproduct or service where repeatable measurements take place then

their test equipment/instruments need to have repetitive outputs.

Without calibration to a traceable standard (national, international,

or intrinsic), there can be no repeatability. Therefore there can be no

quality in the product, so the company would never be able to stay in

business long enough to impact their market segment.

So is there cost and risk? Absolutely. The cost is huge in terms of lost

production, time, money, and reputation. In the case of companies

that have untraceable calibration in the production of medical devices,

pharmaceutical drugs and products that impact human safety – the

cost could be immeasurable…with the possibility of death among theresults.

The basic belief is this – it is absolutely essential to have a quality

calibration program in place to make a quality product, no matter

the size, shape, or quantity. The question that should be asked is:

“Do you have a quality calibration program that has traceable results

to a national or international standard”? If the answer is yes, then it

is assumed that to have a quality calibration program, you must also

have all the parts needed to support traceable calibration: calibration

procedures, calibration records, traceable documentation, an out-of-

tolerance program and procedures, document control procedures, a

training program, continuous process improvements, a comprehensive

calibration management software package, calibration interval

analysis, documented training for all your calibration technicians,

and the ability to provide quality customer service in a timely manner.

Then you can say you have a quality calibration program.

But it doesn’t end there. Referring to a double edged sword, what

are the responsibilities of a quality calibration department and also

those of their customer?

A calibration/metrology department should be responsible for:

• Listening to their customers to understand their requirements

and needs



54

• Translating those requirements to the accuracy and

specifications of the test equipment and support services that

meet or exceed their quality expectations

• Delivering test equipment that consistently meets requirements

for reliable performance

• Providing knowledgeable and comprehensive test equipmentsupport

• Continuously reviewing and improving their services an

processes

Your customers should be responsible for:

• Informing Metrology of their requirements and needs

• Getting the proper training in the correct and safe usage of te

equipment

• Maintaining their test equipment without abusing, contaminatin

or damaging it under normal operating conditions

• Using their work order system for requesting service wheequipment is broken, malfunctioning, or in need of calibration

As Lord Kelvin was quoted as saying, “If you cannot measure it, yo

cannot improve it.”

1. EAL-G12, Traceability of Measurement. Edition 1, Novembe

1995.

2. EA-4/02, Expression of the Uncertainty of Measurement i

Calibration. December 1999 rev00.

3. Bucher, Jay L. 2007. The Quality Calibration Handbook

Milwaukee: ASQ Quality Press.

4. NCSL. 1999. Calibration Control Systems for the Biomedical an

Pharmaceutical Industry, RP-6. Boulder, CO.

5. NCSL International. 2006. ANSI/NCSL Z540.3-2006. Boulde

CO.



55



57

T

oday’s modern process plants, production processes and quality

systems, put new and tight requirements on the accuracy of

process instruments and on process control.

Quality systems, such as the ISO9000 and ISO14000 series of qualitystandards, call for systematic and well-documented calibrations, with

regard to accuracy, repeatability, uncertainty, confidence levels etc.

Does this mean that the electricians and instrumentation people

should be calibration experts? Not really, but this topic should

not be ignored. Fortunately, modern calibration techniques and

calibration systems have made it easier to fulf ill the requirements on

instrumentation calibration and maintenance in a productive way.

However, some understanding of the techniques, terminology and

methods involved in calibration must be known and understood in

order to perform according to International Quality Systems.

1. What is calibration and why calibrate

Calibration can briefly be described as an activity where the

instrument being tested is compared to a known reference value, i.e.

calibrator. The keywords here are ‘known reference’, which means

that the calibrator used should have a valid, traceable calibration

certificate.

To be able to answer the question why calibrate, we must first

determine what measurement is and why measuring is necessary.

Traceable and efficient calibrations

in the process industry

Calibration can briefly be

described as an activity where theinstrument

being tested is compared

to a known reference

value, i.e. calibrator.



58

WHAT IS MEASUREMENT?

In technical standards terms the word measurement has been

defined as:

“A set of experimental operations for the purpose of determining

the value of a quantity.”

What is then the value of quantity? According to the standards

the true value of a quantity is:

“The value which characterizes a quantity perfectly defined

during the conditions which exist at the moment when the value

is observed. Note: the true value of a quantity is an ideal concept

and, in general, it cannot be known.”

Therefore all instruments display false indications!

HIERARCHYOF ACCURACY

TRUE VALUE

Process instrumentation

Instr. Departments

House and working standards

Authorized

Laboratories

International

National standard

A set of experimental

operations for the

purpose of determining

the value of a quantity.



59

2. Why measure?

The purpose of a process plant is to convert raw material, energy,

manpower and capital into products in the best possible way. This

conversion always involves optimizing, which must be done better

than the competitors. In practice, optimization is done by means ofprocess automation. Anyhow, regardless of how advanced the process

automation system is, the control cannot be better than the quality of

measurements from the process.

3. Why calibrate

The primary reason for calibrating is based on the fact that even the

best measuring instruments lack in absolute stability, in other words,

The primary reason for

calibrating is based on

the fact that even the bestmeasuring instruments

lack in absolute stability, in

other words, they drift and

lose their ability to give

accurate measurements.

EVERYTHING IS BASEDON MEASUREMENTS

PROCESSProductionFactors

Products

MEASUREMENTS

MEASUREMENTS

CONTROLS

ADJUSTMENTS

PROCESS CONTROL SYSTEM

INSTRUMENTATION



60

they drift and lose their ability to give accurate measurements. Th

drift makes recalibration necessary.

Environment conditions, elapsed time and type of application ca

all affect the stability of an instrument. Even instruments of the sam

manufacturer, type and range can show varying performance. On

unit can be found to have good stability, while another performdifferently.

Other good reasons for calibration are:

• To maintain the credibility of measurements

• To maintain the quality of process instruments

at a good-as-new level

• Safety and environmental regulations

• ISO9000, other quality systems and regulations

The ISO9000 and ISO14000 can assist in guiding regular, systematcalibrations, which produces uniform quality and minimizes th

negative impacts on the environment.

C1–C7 CALIBRATIONS

PURCHASE

QP – PURCHASED QUALITY

QZM – ZERO MAINTAINED QUALITY

QM – MAINTAINED QUALITY

QUALITY

Q3

Q2

Q1

C1 C2 C3 C4 C5 C6QP

QM

QZM

T1 T2 T3 TIME

LOWERTOLERANCE

“GOOD AS NEW”

QUALITY MAINTENANCE

C7

Environment conditions,

elapsed time and type

of application can all

affect the stability of an

instrument.



61

4. Traceability

Calibrations must be traceable. Traceability is a declaration stating

to which national standard a certain instrument has been compared.

5. Regulatory requirements for calibration

5.1 ISO9001: 2008

The organization determines the monitoring and measurements to

be performed, as well as the measuring devices needed to provide

evidence of a product’s conformity to determined standards.

The organization establishes the processes for ensuring that

measurements and monitoring are carried out and are carried out

in a manner consistent with the monitoring and measurement

requirements.

Where necessary, to ensure valid results, measuring equipmentis calibrated or verified with measurement standards traceable to

national or international standards at specified intervals. If no

such standards exist, the basis used for calibration or verification

is recorded; adjusted or re-adjusted as necessary; identified for the

determining of the calibration status; safeguarded against adjustments

that would invalidate the measurement result; protected from damage

and deterioration during handling, maintenance and storage.

In addition, the organization assesses and records the validity of

the previous measuring results when the equipment is found not to

conform to requirements. The organization then takes appropriate

action on the equipment and any product affected. Records of the

calibration and verification results are then maintained.

When used in the monitoring and measurement of specified

requirements, the ability of computer software to satisfy the intended

application is confirmed. This is done prior to initial use and

reconfirmed as necessary.

Note: See ISO 10012 for further information.

International

standards

National

standards

Reference

standards

Working

standards

Process

standards

SI-UNITS



62

5.2 PHARMACEUTICAL (FDA, U.S. Food and Drug Administration)

Any pharmaceutical company that sells their products in the USA

must comply with FDA regulations, regardless of where the product

are manufactured.

• Calibration records must be maintained.

• Calibrations must be done in accordance with written, approved

procedures.

• There should be a record of the history of each instrument.

• All instrumentation should have a unique ID; all product, proces

and safety instruments should be physically tagged.

• A calibration period and error limits should be defined for each

instrument.

• Calibration standards should be traceable to national and

international standards.

• Calibration standards must be more accurate than the requiredaccuracy of the equipment being calibrated.

• All instruments used must be fit for purpose.

• There must be documented evidence that personnel involved in

the calibration process have been trained and are competent.

• Documented change management system must be in place.

• All electronic systems must comply with FDA’s 21 CFR Part 11.

• All of the above should be implemented in conjunction with

following regulations:

– 21 CFR Part 211 – “Current Good Manufacturing Practice

for Finished Pharmaceuticals”

– 21 CFR Part 11 – “Electronic Records; Electronic Signatures”

Software systems need features such as Electronic Signature, Aud

Trail, User Management, and Security System to be able to compl

with these regulations.

In such a system, the Electronic Signature is considered equivalent t

a hand-written signature. Users must understand their responsibilitie

once they give an electronic signature. An Audit Trail is require

to support change management. Audit Trails should record a

modifications, which add, edit, or delete data from an electroni

record.

Software systems

need features such as

Electronic Signature, Audit

Trail, User Management,

and Security System

to be able to comply

with these regulations.



63

5.3 PHARMACEUTICAL (EU GMPs)

Any pharmaceutical company that sells their products in the European

Union must comply with EU GMPs, including Annex 11, regardless of

where the products are manufactured.

The requirements for EU GMPs are similar to those of the US FDA,as described in Section 5.2.

6. DEFINITIONS OF METROLOGICAL TERMS

Some metrological terms in association with the concept of calibration

are described in this section.

Quite a few of the following terms are also used on specification

sheets for calibrators. Please note that the definitions listed here are

simplified.

Calibration

An unknown measured signal is compared to a known reference

signal.

Validation

Validation of measurement and test methods (procedures) is generally

necessary to prove that the methods are suitable for the intended use.

Non-linearity

Non-linearity is the maximum deviation of a transducer’s output from

a defined straight line. Non-linearity is specified by the Terminal

Based method or the Best Fit Straight Line method.

Resolution

Resolution is the smallest interval that can be read between two

readings.

Validation of measure-

ment and test methods

(procedures) is generally

necessary to prove that

the methods are suitable

for the intended use.



64

Sensitivity

Sensitivity is the smallest variation in input, which can be detected a

an output. Good resolution is required in order to detect sensitivity

Hysteresis

The deviation in output at any point within the instrument’s sensin

range, when first approaching this point with increasing values, an

then with decreasing values.

Repeatability

Repeatability is the capability of an instrument to give the sam

output among repeated inputs of the same value over a period of time

Repeatability is often expressed in the form of standard deviation.

Temperature coefficient

The change in a calibrator’s accuracy caused by changes in ambien

temperature (deviation from reference conditions). The temperatur

coefficient is usually expressed as % F.S. / °C or % of RDG/ °C.

Stability

Often referred to as drift, stability is expressed as the change i

percentage in the calibrated output of an instrument over a specifie

period, usually 90 days to 12 months, under normal operatin

conditions. Drift is usually given as a typical value.

Accuracy

Generally accuracy figures state the closeness of a measured valu

to a known reference value. The accuracy of the reference value

generally not included in the f igures. It must also be checked if erro

like non-linearity, hysteresis, temperature effects etc. are included i

the accuracy figures provided.

Accuracy is usually expressed % F.S. or % of RDG + adder. Th

difference between these two expressions is great. The only way t

compare accuracy presented in different ways is to calculate the tot

error at certain points.

Stability is expressed as

the change in percentage

in the calibrated output

of an instrument over a

specified period, usually

90 days to 12 months,

under normal operating

conditions.



65

Uncertainty

Uncertainty is an estimate of the limits, at a given cover factor (or

confidence level), which contain the true value.

Uncertainty is evaluated according to either a “Type A” or a “Type

B” method. Type A involves the statistical analysis of a series ofmeasurements. In this case, uncertainty is calculated using Type A

uncertainties, i.e. the effects of these components include measurement

errors, which can vary in magnitude and in sign, in an unpredictable

manner. The other group of components, Type B, could be said to be of

a systematic nature. Systematic errors or effects remain constant during

the measurement. Examples of systematic effects include errors in

reference value, set-up of the measuring, ambient conditions, etc. Type

B uncertainty is used when the uncertainty of a single measurement

is expressed.

It should be noted that, in general, errors due to observer fallibility

cannot be accommodated within the calculation of uncertainty.Examples of such errors include: errors in recording data, errors in

calculation, or the use of inappropriate technology.

Type A uncertainty

The type A method of calculation can be applied when several

independent measurements have been made under the same

conditions. If there is suff icient resolution in the measurement, there

will be an observable difference in the values measured.

The standard deviation, often called the “root-mean-square

repeatability error”, for a series of measurements under the same

conditions, is used for calculation. Standard deviation is used as a

measure of the dispersion of values.

Type B uncertainty

Type B evaluation of uncertainty involves the use of other means

to calculate uncertainty, rather than applying statistical analysis of a

series of measurements.

It involves the evaluation of uncertainty using scientific judgement

based on all available information concerning the possible variables.

Values belonging to this category may be derived from:

It should be noted that, in

general, errors due to

observer fallibility cannot

be accommodated within

the calculation

of uncertainty.



66

• Experience with or general knowledge of the behavior

and properties of relevant materials and instruments

• Ambient temperature

• Humidity

• Local gravity

• Atmospheric pressure• Uncertainty of the calibration standard

• Calibration procedures

• Method used to register calibration results

• Method to process calibration results

The proper use of the available information calls for insight base

on experience and general knowledge. It is a skill that can be learn

with practice. A well-based Type B evaluation of uncertainty ca

be as reliable as a Type A evaluation of uncertainty, especially i

a measurement situation where a Type A evaluation is based onl

on a comparatively small number of statistically independenmeasurements.

Expanded uncertainty

The EA has decided that calibration laboratories accredite

by members of the EA shall state an expanded uncertainty o

measurement obtained by multiplying the uncertainty by a coverag

factor k. In cases where normal (Gaussian) distribution can b

assumed, the standard coverage factor, k=2, should be used. Th

expanded uncertainty corresponds to a coverage probability (o

confidence level) of approximately 95%.

For uncertainty specifications, there must be a clear statement o

cover probability or confidence level. Usually one of the followin

confidence levels are used:

1 s = 68%

2 s = 95%

3 s = 99%

7. CALIBRATION MANAGEMENT Many companies do not pay enough attention to calibratio

management although it is a requirement e.g. in ISO9001: 2008

The maintenance management system may alert when calibration

For uncertainty

specifications, there

must be a clear state-

ment of cover probability

or confidence level.



67

needed and then opens up a work order. Once the job has been done,

the work order will close and the maintenance system will be satisfied.

Unfortunately, what happens between opening and closing of the

work order is not documented very often. If something is documented,

it is usually in the form of a hand-written sheet that is then archived.

If the calibration results need to be examined at a later time, findingthe sheets requires a lot of effort.

Choosing professional tools for maintaining calibration records

and doing the calibrations can save a lot of time, effort and money.

An efficient calibration management system consists of calibration

management software and documenting calibrators.

Modern calibration management software can be a tool that

automates and simplifies calibration work at all levels. It automatically

creates a list of instruments waiting to be calibrated in the near future.

If the software is able to interface with other systems the scheduling

of calibrations can be done in the maintenance system from which

the work orders can be automatically loaded into the calibrationmanagement software.

When the technician is about to calibrate an instrument, (s)he simply

downloads the instrument details from the calibration management

software into the memory of a documenting calibrator; no printed

notes, etc. are needed. The “As Found” and “As Left” are saved in the

calibrator’s memory, and there is no need to write down anything

with pen.

The instrument’s measurement ranges and error limits are defined in

the software and also downloaded to the calibrator. Thus the calibrator

is able to detect if the calibration was passed or failed immediately after

the last calibration point was recorded. There is no need to make tricky

calculations manually in the field.

All this saves an extensive amount of time and prevents the user

from making mistakes. The increase in work productivity allows for

more calibrations to be carried out within the same period of time

as before. Depending on what process variable is calibrated and how

many calibration points are recorded, using automated tools can be 5

to 10 times faster compared to manual recording.

While the calibration results are uploaded onto the database, the

software automatically detects the calibrator that was used, and the

traceability chain is documented without requiring any further actions

from the user.

Calibration records, including the full calibration history of an

The instrument’s

measurement ranges

and error limits are

defined in the software

and also downloaded

to the calibrator.



68

instrument, are kept in the database; therefore accessing previou

results is also possible in just a few seconds. When an instrument ha

been calibrated several times, software displays the “History Trend

which assists in determining whether or not the calibration perio

should be changed.

One of today’s trends is to move towards to a paperless office. If thcalibration management software includes the right tools, it is possib

to manage calibration records on computer without producing an

papers. If paper copies of certificates are preferred, printing them mus

of course, be possible. When all calibration related data is located i

a single database the software is obviously able to create calibratio

related reports and documents.

Today’s documenting calibrators are capable of calibrating man

process signals. It is not very uncommon to have a calibrator tha

calibrates pressure, temperature and electrical signals includin

frequency and pulses. In addition to the conventional mA output o

a transmitter, modern calibrators can also read HART, FoundatioFieldbus or Profibus output of the transmitters, and they can be eve

used for configuring these “smart” transmitters.

Implementing a modern calibration management system benefit

everybody who has anything to do with instrumentation. For instanc

the maintenance manager can use it as a calibration planning an

decision-making tool for tracking and managing all calibration relate

activities.

When an auditor comes for a visit, QA will find a calibratio

management system useful. The requested calibration records ca

be viewed on screen with a couple mouse clicks. If a calibrator drift

out of its specifications, it is possible to use a “reverse traceabilit

report” to get a list of instruments that have been calibrated with tha

calibrator.

Good calibration tools help technicians work more efficiently an

accurately. If the system manufacturer has paid attention usability

the system is easy to learn and use. When many tasks are automated

the users can concentrate on their primary job.

Transferring to a new calibration system may sound like a huge tas

and it can be a huge task. There are probably thousands of instrumen

that need to be entered into the database and all the details must b

checked and verified before the system is up and running. Althoug

there is a lot of data involved, it does not mean the job is an enormou

one.

Implementing a modern

calibration management

system benefits

everybody who has

anything to do with

instrumentation.



69

A good, automated

calibration system

reduces workload.

CONCLUSION

A good, automated calibration system reduces workload

because it carries out tasks faster, more accurately and with

better results than what could be reached with a manual system.

It assists in documenting, scheduling, planning, analyzing and

finally optimizing the calibration work.

References

[1] ISO9001: 2008 “Quality Management Systems.

Requirements”

[2] 21 CFR Part 11: “Electronic Records;

Electronic Signatures”

[3] 21 CFR Part 211: “Current Good Manufacturing Practice

for Finished Pharmaceuticals”

Nowadays most companies have instrumentation data in some type

of electronic format: as Excel spreadsheets, Maintenance databases,

etc. The vendor of the calibration system is most likely able to import

most of the existing data to the calibration database saving months

of work.



CalibrationManagement and

Maintenance



73

Calibration can be briefly described as an activity where the

instrument being tested is compared to a known reference

value. At the simplest level, calibration is a comparison between

measurements – one of known magnitude or correctness made or set

with one device, and another measurement made in as similar a way aspossible with a second device. The device with the known or assigned

correctness is called the standard. The second device is the unit under

test or test instrument.

Calibration is often required with a new instrument or when a

specified time period or a specified number of operating hours

has elapsed. In addition, calibration is usually carried out when an

instrument has been subjected to an unexpected shock or vibration

that may have put it out of its specif ied limits.

Calibration in industrial applications

When a sensor or instrument experiences temperature variations or

physical stress over time, its performance will invariably begin to

decline, which is known as ‘drift’. This means that measurement data

from the sensor becomes unreliable and could even affect the quality

of a company’s production.

Although drift cannot be completely eliminated, it can be discovered

and rectified via calibration. The purpose of calibration is to determine

how accurate an instrument or sensor is. Although most instruments

provide high accuracy these days, regulatory bodies often need to

know just how inaccurate a particular instrument is and whether it

drifts in and out of specified tolerance over time.

Why Calibrate?

What is the risk of not calibrating?

Although drift cannot be

completely eliminated, it

can be discovered and

rectified via calibration.



74

The costs and risks of not calibrating

Unfortunately, calibration has costs associated with it and in uncertai

economic times, this activity can often become neglected or th

interval between calibration checks on instruments can be extended i

order to cut costs or simply through a lack of resources or manpoweHowever, neglecting calibration can lead to unscheduled productio

or machine downtime, product and process quality issues or eve

product recalls and rework.

Furthermore, if the instrument is critical to a process or is locate

in a hazardous area, allowing that sensor to drift over time coul

potentially result in a risk to employee safety. Similarly, an end produ

manufactured by a plant with poorly calibrated instruments coul

present a risk to both consumers and customers. In certain situation

this may even lead to a company losing its license to operate due t

company not meeting its regulatory requirements. This is particularl

true for the food and beverage sector and for pharmaceuticamanufacturers.

Weighing instruments also need to be calibrated regularly

Determining the correct mass of a product or material is particularl

important for companies that supply steel, paper and pulp, powe

aviation companies, harbors and retail outlets, who invoice custome

based on the mass of what they supply (fiscal metering). Thes

companies need to prove not only that the mass is accurate but als

that the equipment producing the readings was correctly calibrated

Invoicing in these industries is often based on process measurement

There is therefore a growing need to have the metrological quality o

these weighing instruments confirmed by calibration.

Product manufacturing also depends on accurate masses and s

laboratories and production departments in the food and beverage

oil and gas, energy, chemical and pharmaceutical industries, also nee

to calibrate their weighing instruments.

Why is calibration important?

Calibration ensures that instrument drift is minimized. Even th

highest quality instruments will drift over time and lose their abilit

to provide accurate measurements. It is therefore critical that a

instruments are calibrated at appropriate intervals.

The stability of an instrument very much depends on its applicatio

and the environment it operates in. Fluctuating temperatures, hars

Even the highest quality

instruments will drif t

over time and lose their

ability to provide accurate

measurements.



75

manufacturing conditions (dust and dirt) and elapsed time are all

contributing factors here. Even instruments manufactured by the same

supplier can vary in their performance over time.

Calibration also ensures that product or batch quality remains high

and consistent over time. Quality systems such as ISO 9001, ISO 9002

and ISO 14001 require systematic, well-documented calibrations withrespect to accuracy, repeatability, uncertainty and confidence levels.

This affects all process manufacturers.

Armando Rivero Rubalcaba is head of Instrumentation at beer

producer Heineken (Spain). He comments: “For Heineken, the quality

of the beer is a number one priority. All the plants in Spain have

received ISO 9001 and ISO 14001 certifications, in addition to the BRC

certificate of food safety. We must therefore ensure that all processes

correspond to the planned characteristics. The role of calibration is very

important to ensure the quality and safety of the processes.”

Pharmaceutical manufacturers must follow current Good

Manufacturing Practices, GMP, requires that calibration records aremaintained and calibrations have to be carried out in accordance

with written, approved procedures. Typically, each instrument has a

master history record and a unique ID. All product, process and safety

instruments should also be physically tagged.

Furthermore, a calibration interval and error limits should be

defined for each instrument and standards should be traceable to

national and international standards. Standards must also be more

accurate than the required accuracy of the equipment being calibrated.

On the people side, there must be documented evidence that

employees involved in the calibration process have been properly

trained and competent. The company must also have a documented

change management system in place, with all electronic systems

complying with FDA regulations 21 CFR Part 11.

In the power generation, energy and utilities industries, instrument

calibration can help to optimize a company’s production process or to

increase the plant’s production capacity. For example, at the Almaraz

Nuclear Power Plant in Spain, by improving the measurement of

reactor power parameters from 2% to 0.4%, enabled the reactor power

in each unit to be increased by 1.6%, which has a significant effect on

annual production capacity.

Safety is another important reason to calibrate instruments.

Production environments are potentially high risk areas for employees

and can involve high temperatures and high pressures. Incorrect

measurements in a hazardous area could lead to serious consequences,

The role of calibration is

very important to ensure

the quality and safety of

the processes.



76

Calibration is of great

importance, especially

from the viewpoint of

production safety and

quality of the final product.

particularly in the oil and gas, petrochemicals and chemicals sector

Similarly, manufacturers of food and beverage or pharmaceutica

products could put their customers’ lives at risk by neglecting t

calibrate their process instruments.

Heikki Karhe is a measurement technician at the tyre manufacture

Nokian Tyres. As he puts it: “Calibration is of great importanceespecially from the viewpoint of production safety and quality o

the final product. Preparation of the right rubber mixture is precisio

work and a sample is taken from each rubber mixture to ensure quality

Measuring instruments that yield wrong values could easily ruin th

final product. The factory is also full of pressure instruments and so

is also important for the safety of the workers that those instrumen

show the right values.”

Neglecting to calibrate process instruments can also affect

company’s bottom line profits. This is particularly true if sale

invoicing is based on accurate process measurements, for example

weighing scales or gas conversion devices. Indeed, according to recenresearch by Nielsen Research/ ATS Studies, poor quality calibratio

is on average costing manufacturers more than 1.7 million US dolla

every year. When only large companies with revenues of more than

billion US dollars are considered, this figure rises dramatically to mor

than 4 million US dollars per year.

Proper invoicing is therefore critical to energy and utilitie

companies. As Jacek Midera, measurement specialist at Mazovian Ga

Company states: “Most importantly, accurate measurements ensur

proper billing. The impact of even a small measurement error ca

be tremendous in terms of lost revenue. Customers want to pay fo

the exact amount of gas they’ve received. Therefore, gas conversio

devices must be extremely accurate in measuring delivered gas. Th

means that requirements for the calibrators are especially high.”

Today, controlling emissions is another critical factor for man

process manufacturers. Calibrating instruments can help to mak

combustion more efficient in industrial ovens and furnaces. Th

latest Government regulations relating to carbon emissions may als

require that companies calibrate specific instruments on a regula

basis, including sensors used for measuring CO2 and NO

X emission

As Ed de Jong, Instrument Maintenance Engineer at She

(Netherlands) explains: “Until recently, calibration was mainly drive

by economic motives: even the smallest of errors in delivery quantitie

are unacceptable in Shell’s operation due to the vast sums of mone



77

involved for both customers and governments [fiscal metering].

Nowadays, calibration has an important role especially for the license

to operate. Government regulations demand that specific instruments

must be calibrated, for example, instruments related to CO2 and NO

X

emissions.”

Common misconceptions

There are some common misconceptions when it comes to instrument

calibration. For example, some manufacturers claim that they do not

need to calibrate their fieldbus instruments because they are digital

and so are always accurate and correct. This is simply not true. The

main difference between fieldbus and conventional transmitters

is that the output signal is a fully digital fieldbus signal. Changing

the output signal does not change the need for periodic calibration.

Although fieldbus transmitters have been improved in terms of their

measurement accuracy when compared to analogue transmitters, thisdoes not eliminate the need for calibration.

Another common misunderstanding is that new instruments do

not require calibration. Again, this is not true. Just because a sensor is

newly installed does not mean that it will perform within the required

specifications. By calibrating an instrument before installation,

a company is able to enter all the necessary instrument data to its

calibration database or calibration management software, as well as

begin to monitor the stability or drift of the instrument over time.

When to calibrate

Due to drift, all instruments require calibrating at set intervals. How

often they are calibrated depends on a number of factors. First, the

manufacturer of the instrument will provide a recommended calibration

interval. This interval may be decreased if the instrument is being used

in a critical process or application. Quality standards may also dictate

how often a pressure or temperature sensor needs calibrating.

The most effective method of determining when an instrument

requires calibrating is to use some sort of history trend analysis. The

optimal calibration interval for different instruments can only be

determined with software-based history trend analysis. In this way,

highly stable sensors are not calibrated as often as those sensors that

are more susceptible to drift.

The most effective

method of determining

when an instrument

requires calibrating is to

use some sort of history

trend analysis.



78



79

Every manufacturing plant has some sort of system in place for

managing instrument calibration operations and data. Plant

instrumentation devices such as temperature sensors, pressure

transducers and weighing instruments – require regular calibration

to ensure they are performing and measuring to specif ied tolerances.However, different companies from a diverse range of industry

sectors use very different methods of managing these calibrations.

These methods differ greatly in terms of cost, quality, efficiency, and

accuracy of data and their level of automation.

Calibration software is one such tool that can be used to support and

guide calibration management activities, with documentation being

a critical part of this.

But in order to understand how software can help process plants

better manage their instrument calibrations, it is important to consider

the typical calibration management tasks that companies have to

undertake. There are five main areas here, comprising of planning

and decision-making; organisation; execution; documentation; and

analysis.

Careful planning and decision-making is important. All plant

instruments and measurement devices need to be listed, then classified

into ‘critical’ and ‘non-critical’ devices. Once this has been agreed,

the calibration range and required tolerances need to be identified.

Decisions then need to be made regarding the calibration interval for

each instrument. The creation and approval of standard operating

procedures (SOPs) for each device is then required, followed by the

selection of suitable calibration methods and tools for execution of

these methods. Finally, the company must identify current calibration

status for every instrument across the plant.

Why use software forcalibration management?

Calibration software

is one such tool that

can be used to support

and guide calibration

management activities,

with documentation being

a critical part of this.



80

The next stage, organisation, involves training the company

calibration staff – typically maintenance technicians, servic

engineers, process and quality engineers and managers – in using th

chosen tools and how to follow the approved SOPs. Resources the

have to be organised and assigned to actually carry out the schedule

calibration tasks.The execution stage involves supervising the assigned calibratio

tasks. Staff carrying out these activities must follow the appropriat

instructions before calibrating the device, including any associate

safety procedures. The calibration is then executed according to the plan

although further instructions may need to be followed after calibration

The documentation and storage of calibration results typicall

involves signing and approving all calibration records that are generated

The next calibration tasks then have to be scheduled, calibration labe

need to be created and pasted, then created documents copied an

archived.

Based on the calibration results, companies then have to analyse thdata to see if any corrective action needs to be taken. The effectivene

of calibration needs to be reviewed and calibration intervals checked

These intervals may need to be adjusted based on archived calibratio

history. If, for example, a sensor drifts out of its specification range

the consequences could be disastrous for the plant, resulting in costl

production downtime, a safety problem or leading to batches of inferio

quality goods being produced, which may then have to be scrapped.

Documentation

Documentation is a very important part of a calibration managemen

process. ISO 9001:2008 and the FDA both state that calibratio

records must be maintained and that calibration must be carried ou

according to written, approved procedures.

This means an instrument engineer can spend as much as 50 pe

cent of his or her time on documentation and paperwork – time tha

could be better spent on other value-added activities. This paperwor

typically involves preparing calibration instructions to help fiel

engineers; making notes of calibration results in the field; an

documenting and archiving calibration data.

Imagine how long and difficult a task this is if the plant ha

thousands of instruments that require calibrating on at least a six

monthly basis? The amount of manual documentation increase

almost exponentially!

All plant instruments and

measurement devices

need to be listed, then

classified into ‘critical’

and ‘non-critical’ devices.



81

When it comes to the volume of documentation required, different

industry sectors have different requirements and regulations. In the

Power & Energy sector, for example, just under a third of companies

(with 500+ employees) typically have more than 5,000 instruments

that require calibrating. 42 per cent of companies perform more than

2,000 calibrations each year.In the highly regulated pharmaceuticals sector, a massive 75 per cent

of companies carry out more than 2,000 calibrations per year. Oil,

Gas & Petrochemicals is similarly high, with 55 per cent of companies

performing more than 2,000 calibrations each year. The percentage

is still quite high in the food & beverage sector, where 21 per cent of

firms said they calibrated their instruments more than 2,000 times

every year. This equates to a huge amount of paperwork for any process

plant.

The figures outlined appear to suggest that companies really

do require some sort of software tool to help them manage their

instrument calibration processes and all associated documentation.However, the picture in reality can be very different.

Only a quarter of companies use calibration software

In Beamex’s own Calibration Study carried out recently, a mere 25

per cent of companies with 500+ employees (across the industry

sectors mentioned above) said that they did use specialist calibration

management software. Many other companies said that they relied

on generic spreadsheets and/or databases for this, whilst others used

a calibration module within an existing Computerised Maintenance

Management System (CMMS). A signif icant proportion (almost 20 per

cent) of those surveyed said they used a manual, paper-based system.

Any type of paper-based calibration system will be prone to human

error. Noting down calibration results by hand in the f ield and then

transferring these results into a spreadsheet back at the office may

seem archaic, but many firms still do this. Furthermore, analysis of

paper-based systems and spreadsheets can be almost impossible, let

alone time consuming.

In a recent survey conducted by Control Magazine, 40 per cent of

companies surveyed said that they calculated calibration intervals by

using historical trend analysis – which is encouraging. However, many

of these firms said they were doing it without any sort of calibration

software to assist them. The other 60 per cent of companies determined

This means an instrument

engineer can spend

as much as 50 per

cent of his or her time

on documentation and

paperwork – time that

could be better spent

on other value-added

activities.



82

instrument calibration intervals based on either the manufacturer’s ow

recommendation, or they used a uniform interval across the plant fo

all instruments. Neither method is ideal in practice. Companies coul

save so much time and reduce costs by using calibration managemen

software to analyse historical trends and calibration results.

Using software for calibration management enables faster, easier anmore accurate analysis of calibration records and identifying historica

trends. Plants can therefore reduce costs and optimise calibratio

intervals by reducing calibration frequency when this is possible, o

by increasing the frequency where necessary.

For example, for improved safety, a process plant may find

necessary to increase the frequency of some sensors that are located i

a hazardous, potentially explosive area of the manufacturing plant.

Just as important, by analysing the calibration history of a flo

meter that is located in a ‘non-critical’ area of the plant, the compan

may be able to decrease the frequency of calibration, saving time an

resources. Rather than rely on the manufacturer’s recommendation focalibration intervals, the plant may be able to extend these intervals b

looking closely at historical trends provided by calibration managemen

software. Instrument ‘drift’ can be monitored closely over a period o

time and then decisions taken confidently with respect to amendin

the calibration interval.

Regardless of industry sector, there seems to be some genera

challenges that companies face when it comes to calibratio

management.

The number of instruments and the total number of periodi

calibrations that these devices require can be several thousand per yea

How to plan and keep track of each instrument’s calibration procedure

means that planning and scheduling is important. Furthermore, ever

instrument calibration has to be documented and these documen

need to be easily accessible for audit purposes.

Paper-based systems

These systems typically involve hand-written documents. Typicall

this might include engineers using pens and paper to record calibratio

results while out in the field. On returning to the off ice, these note

are then tidied up or transferred to another paper document, afte

which they are archived as paper documents.

While using a manual, paper-based system requires little or n

Using software for


enables faster, easier and

more accurate analysis

of calibration records

and identifying historical

trends.



83

investment, it is very labour-intensive and means that historical trend

analysis becomes very diff icult to carry out. In addition, the calibration

data is not easily accessible. The system is time consuming, soaks up a

lot of resources and typing errors are commonplace. Dual effort and

re-keying of calibration data are also significant costs here.

In-house legacy systems (spreadsheets, databases, etc.)

Although certainly a step in the right direction, using an in-house

legacy system to manage calibrations has its drawbacks. In these

systems, calibration data is typically entered manually into a

spreadsheet or database. The data is stored in electronic format, but

the recording of calibration information is still t ime-consuming and

typing errors are common. Also, the calibration process itself cannot

be automated. For example, automatic alarms cannot be set up on

instruments that are due for calibration.

Calibration module of a CMMS

Many plants have already invested in a Computerised Maintenance

Management (CMM) system and so continue to use this for calibration

management. Plant hierarchy and works orders can be stored in the

CMM system, but the calibration cannot be automated because the

system is not able to communicate with ‘smart’ calibrators.

Furthermore, CMM systems are not designed to manage calibrations

and so often only provide the minimum calibration functionality, such

as the scheduling of tasks and entry of calibration results. Although

instrument data can be stored and managed efficiently in the plant’s

database, the level of automation is still low. In addition, the CMM

system may not meet the regulatory requirements (e.g. FDA) for

managing calibration records.


With specialist calibration management software, users are provided

with an easy-to-use Windows Explorer-like interface. The software

manages and stores all instrument and calibration data. This

includes the planning and scheduling of calibration work; analysis

and optimisation of calibration frequency; production of reports,

certificates and labels; communication with smart calibrators; and

Regardless of industry

sector, there seems to be

some general challenges

that companies face

when it comes to

calibration management.



84

easy integration with CMM systems such as SAP and Maximo. Th

result is a streamlined, automated calibration process, which improve

quality, plant productivity and eff iciency.

Benefits of using calibration softwareWith software-based calibration management, planning and decision

making are improved. Procedures and calibration strategies can b

planned and all calibration assets managed by the software. Position

device and calibrator databases are maintained, while automatic alert

for scheduled calibrations can be set up.

Organisation also improves. The system no longer requires pens an

paper. Calibration instructions are created using the software to guid

engineers through the calibration process. These instructions can als

be downloaded to a technician’s handheld documenting calibrato

while they are in the field.

Execution is more efficient and errors are eliminated. Usinsoftware-based calibration management systems in conjunction wit

documenting calibrators means that calibration results can be store

in the calibrator’s memory, then automatically uploaded back to th

calibration software. There is no re-keying of calibration results from

a notebook to a database or spreadsheet. Human error is minimise

and engineers are freed up to perform more strategic analysis or othe

important activities.

Documentation is also improved. The software generates report

automatically and all calibration data is stored in one database rathe

than multiple disparate systems. Calibration certif icates, reports an

labels can all be printed out on paper or sent in electronic format.

Analysis becomes easier too, enabling engineers to optimise calibratio

intervals using the software’s History Trend function.

Also, when a plant is being audited, calibration software ca

facilitate both the preparation and the audit itself. Locating record

and verifying that the system works is effortless when compared t

traditional calibration record keeping.

Regulatory organisations and standards such as FDA and ISO

place demanding requirements on the recording of calibration data

Calibration software has many functions that help in meeting thes

requirements, such as Change Management, Audit Trail and Electroni

Signature functions. The Change Management feature in Beamex

CMX software, for example, complies with FDA requirements.

Using software for


enables faster, easier and

more accurate analysis

of calibration records

and identifying historical

trends.



85

Business benefits

For the business, implementing software-based calibration management

means overall costs will be reduced. These savings come from the

now-paperless calibration process, with no manual documentation

procedures. Engineers can analyse calibration results to see whetherthe calibration intervals on plant instruments can be altered. For

example, those instruments that perform better than expected may

well justify a reduction in their calibration frequency.

Plant efficiencies should also improve, as the entire calibration process

is now streamlined and automated. Manual procedures are replaced

with automated, validated processes, which is particularly beneficial if

the company is replacing a lot of labour-intensive calibration activities.

Costly production downtime will also be reduced.

Even if a plant has already implemented a CMM system, calibration

management software can be easily integrated to this system. If the

plant instruments are already def ined on a database, the calibrationmanagement software can utilise the records available in the CMM

system database.

The integration will save time, reduce costs and increase productivity

by preventing unnecessary double effort and re-keying of works orders

in multiple systems. Integration also enables the plant to automate its

calibration management with smart calibrators, which simply is not

possible with a standalone CMM system.

Benefits for all process plants

Beamex’s suite of calibration management software can benefit all

sizes of process plant. For relatively small plants, where calibration

data is needed for only one location, only a few instruments require

calibrating and where regulatory compliance is minimal, Beamex

CMX Light is the most appropriate software.

For medium-to-large sized companies that have multiple users who

have to deal with a large amount of instruments and calibration work, as

well as strict regulatory compliance, Beamex CMX Professional is ideal.

Beamex’s high-end solution, CMX Enterprise, is suitable for process

manufacturers with multiple global sites, multilingual users and a very

large amount of instruments that require calibration. Here, a central

calibration management database is often implemented that is used

by multiple plants across the world.

Choosing the right

calibration software

• Is it easy to use?

• What are the specific

requirements in terms

of functionality?

• Are there any IT

requirements or

restrictions for choosing

the software?

• Does the calibration

software need to beintegrated with the plant’s

existing systems?

• Is communication with

smart calibrators a

requirement?

• Does the supplier offer

training, implementation,

support and upgrades?

• Does the calibration

software need to bescalable?

• Can data be imported

to the software from the

plant’s current systems?

• Does the software offer

regulatory compliance?

• Supplier’s references and

experience as a software

developer?

CHECKLIST



86

Beamex users

Beamex conducted recently a survey of its customers, across a

industry sectors. The results showed that 82% of CMX Calibratio

software customers said that using Beamex products had resulted i

cost savings in some part of their operations.94% of CMX users stated that using Beamex products had improve

the efficiency of their calibration processes, whilst 92% said that usin

CMX had improved the quality of their calibration system.

Summary

Every type of process plant, regardless of industry sector, can benef

from implementing specialist calibration management software

Compared to traditional, paper-based systems, in-house built legac

calibration systems or calibration modules with CMM systems, usin

dedicated calibration management software results in improvequality, increased productivity and reduced costs of the entir

calibration process.

Despite these benefits, only one quarter of companies who nee

to manage instrument calibrations actually use software designed fo

that purpose.

SUMMARY


improves calibration

management tasks

in all these areas

• Planning &

decision-making

• Organisation

• Execution

• Documentation

• Analysis

The business benefits

of using software for


• Cost reduction

• Quality improvements

• Increase in efficiency



87



89

Plants can improve their efficiency and reduce costs by performing

calibration history trend analysis. By doing it, a plant is able

to define which instruments can be calibrated less frequentlyand which should be calibrated more frequently. Calibration

history trend analysis is only possible with calibration software

that provides this functionality.

Adjusting calibration intervals based on history trend analysis

Manufacturing plants need to be absolutely confident that their

instrumentation products – temperature sensors, pressure transducers,

flow meters and the like – are performing and measuring to specified

tolerances. If sensors drift out of their specification range, the

consequences can be disastrous for a plant, resulting in costly production

downtime, safety issues or possibly leading to batches of inferior quality

goods being produced, which then have to be scrapped.

Most process manufacturing plants will have some sort of

maintenance plan or schedule in place, which ensures that all

instruments used across the site are calibrated at the appropriate times.

However, with increasing demands and cost issues being placed on

manufacturers these days, the time and resources required to carry

out these calibration checks are often scarce. This can sometimes lead

to instruments being prioritised for calibration, with those deemed

critical enough receiving the required regular checks, but for other

sensors that are deemed less critical to production, being calibrated

less frequently or not at all.

How often should

instruments be calibrated

Plants can improve their

efficiencies and reducecosts by using calibration

‘history trend analysis’,

a function available within

Beamex ® CMX calibration

software.



90

But plants can improve their efficiencies and reduce costs b

using calibration ‘history trend analysis’, a function available withi

Beamex® CMX calibration software. With this function, the plan

can analyze whether it should increase or decrease the calibratio

frequency for all its instruments.

Cost savings can be achieved in several ways. First, by calibratinless frequently where instruments appear to be highly stable accordin

to their calibration history. Second, by calibrating instruments mor

often when they are located in critical areas of the plant, ensurin

that instruments are checked and corrected before they drift ou

of tolerance. This type of practise is common in companies tha

employ an effective ‘Preventive Maintenance’ regime. The analyse

of historical trends and how a pressure sensor, for example, drifts i

and out of tolerance over a given time period, is only possible wit

calibration software that provides this type of functionality.

Current practices in process plants

But in reality, how often do process plants actually calibrate the

instruments and how does a maintenance manager or engineer kno

how often to calibrate a particular sensor?

In March 2010, Beamex conducted a survey that asked proces

manufacturing companies how many instruments in their plan

required calibrating and the frequency with which these instrumen

had to be calibrated. The survey covered all industry sectors, includin

pharmaceuticals, chemicals, power and energy, manufacturing

service, food and beverage, oil and gas, paper and pulp.

Interestingly, the survey showed that from all industry sectors, 56%

of the respondents said they calibrated their instruments no mor

than once a year.

However, in the pharmaceuticals sector, 59% said they calibrate

once a year and 30% said they calibrated twice a year.

Perhaps unsurprisingly, due to it being a highly regulated industry

the study proved also that the pharmaceuticals sector typicall

possesses a significantly higher number of instruments per plan

that require calibrating. In addition, these plants also calibrate the

instruments more frequently than other industry sectors.

Sensors that are found

to be highly stable do not

need to be re-calibrated

as often as sensors that

tend to drift.



91

The benefits of analyzing calibration history trends

But regardless of the industry sector, by analysing an instrument’s

drift over time (ie. the historical trend) companies can reduce

costs and improve their efficiencies. Pertti Mäki is Area Sales

Manager at Beamex. He specialises in selling the Beamex® CMXto different customers across all industry sectors. He comments:

“The largest savings from using the History Trend Option are in the

pharmaceuticals sector, without doubt, but all industry sectors can

benefit from using the software tool, which helps companies identify

the optimal calibration intervals for instruments.”

The trick, says Mäki, is determining which sensors should be re-

calibrated after a few days, weeks, or even years of operation and which

can be left for longer periods, without of course sacrificing the quality

of the product or process or the safety of the plant and its employees.

Doing this, he says, enables maintenance staff to concentrate their

efforts only where they are needed, therefore eliminating unnecessarycalibration effort and time.

But there are other, perhaps less obvious benefits of looking at the

historical drift over time of a particular sensor or set of measuring

instruments. As Mäki explains: “When an engineer buys a particular

sensor, the supplier provides a technical specification that includes details

on what the maximum drift of that sensor should be over a given time

period. With CMX’s History Trend Option, the engineer can now verify

that the sensor he or she has purchased, actually performed within the

specified tolerance over a certain time period. If it hasn’t, the engineer

now has data to present to the supplier to support his findings.”

But that’s not all. The History Trend function also means that a

plant can now compare the quality or performance of different sensors

from multiple manufacturers in a given location or set of process

conditions. This makes it an invaluable tool for maintenance or quality

personnel who, in setting up a new process line for example, can use

the functionality to compare different sensor types to see which one

best suits the new process.

Calibration software such as CMX can also help with the planning

of calibration operations. Calibration schedules take into account

the accuracy required for a particular sensor and the length of time

during which it has previously been able to maintain that degree of

accuracy. Sensors that are found to be highly stable do not need to be

re-calibrated as often as sensors that tend to drift.

The function enables

users to plan the optimal

calibration intervals for

their instruments.



92

The History Trend function enables users to plan the optima

calibration intervals for their instruments. Once implemented

maintenance personnel, for example, can analyze an instrument’s drif

over a certain time period. History Trend displays the instrument

drift over a given period both numerically and graphically. Based o

this information, it is then possible to make decisions and conclusionregarding the optimal calibration interval and the quality of th

instruments with respect to measurement performance.

The ‘History Trend’ window enables users to view key figures o

several calibration events simultaneously, allowing to evaluate th

calibrations of a position or a device for a longer time period compare

to the normal calibration result view.

For example, the user can get an overview of how a particular devic

drifts between calibrations and also whether the drift increases wit

time. Also, the engineer can analyze how different devices are suite

for use in a particular area of the plant or process.

Reporting is straightforward and the user can even tailor the reporto suit his or her individual needs, using the ‘Report Design’ too

option.

History Trend displays

the instrument’s drift

over a given period

both numerically

and graphically.



93

Calibration history trend analysis allows you to analyze the

instrument’s drift over a certain time period.

• The Beamex® CMX stores every calibration event into the

database; the history trend is made automatically without any

extra manual work.

• The Beamex® CMX also indicates when new devices have

been installed and calibrated. This helps in comparing

differences between devices.

• The graphical display of the history trend helps in visualizing

and optimizing the calibration interval for the instruments.

CALIBRATION HISTORY TREND ANALYSIS

H I S T O R Y T R E N D

U S E R - I N T E R F A C

E

H I S T O R Y T R E N D

R E P O R T

The graphical display

of the history trend

helps in visualizing and

optimizing the calibration

interval for the

instruments.



94

SUMMARY

The benefits of calibration history trend analysis:

• Analyzing and determining the optimal calibration interval for

instruments

• Conclusions can be made regarding the quality of a particular

measuring instrument

• Time savings: faster analyses is possible when compared to

traditional, manual methods

• Enables engineers to check that the instruments they have

purchased for the plant are performing to their technical

specifications and are not drifting out of tolerance regularly

• Supplier evaluation: the performance and quality of different

sensors from different manufacturers can be compared

quickly and easily.

When calibration frequency can be decreased:

• If the instrument has performed to specification and the drift

has been insignificant compared to its specified tolerance

• If the instrument is deemed to be non-critical or in a low

priority location

When calibration frequency should be increased:

• If the sensor has drifted outside of its specified tolerances

during a given time period

• If the sensor is located in a critical process or area of the

plant and has drifted significantly compared to its specified

tolerance over a given time period

• When measuring a sensor that is located in an area of the

plant that has high economic importance for the plant

• Where costly production downtime may occur as a result of

a ‘faulty’ sensor

• Where a false measurement from a sensor could lead to

inferior quality batches or a safety issue



95

ISO 9001:2008 quality management requirements



97

As a general rule for Beamex’s documenting MC calibrators,

starting with a 1-year calibration period is recommended,

because the calibrators has a 1-year uncertainty specified.The calibration period can be changed in the future, once you

begin receiving cumulated stability history, which is then compared

to the uncertainty requirements. In any case, there are many issues

to be considered when deciding a calibrator’s calibration period, or

the calibration period for any type of measuring device. This article

discusses some of the things to be considered when determining the

calibration period, and provides some general guidelines for making

this decision. The guidelines that apply to a calibrator, also apply to

other measuring equipment in the traceability chain. These guidelines

can also be used for process instrumentation.

An important aspect to consider when maintaining a traceable

calibration system is to determine how often the calibration equipment

should be recalibrated. International standards (such as ISO9000,

ISO10012, ISO17025, CFRs by FDA, GMP, etc.) require the use

of documented calibration programs. This means that measuring

equipment should be calibrated traceably at appropriate intervals and

that the basis for the calibration intervals should be evaluated and

documented.

When determining an appropriate calibration period for any

measuring equipment, there are several things to be considered. They

are discussed below.

How often should

calibrators be calibrated

Uncertainty need is

one of the most importantthings to consider when

determining the calibration

period.



98

Uncertainty need

One of the first things to evaluate is the uncertainty need of th

customer for their particular measurement device. Actually, the initi

selection of the measurement device should be also done based on th

evaluation. Uncertainty need is one of the most important things tconsider when determining the calibration period.

Stability history

When the customer has evaluated his/her needs and purchased suitabl

measuring equipment, (s)he should monitor the stability history of th

measuring equipment. The stability history is important criteria whe

deciding upon any changes in the calibration period. Comparing th

stability history of measuring equipment to the specified limits an

uncertainty needs provides a feasible tool for evaluating the calibratio

period. Naturally, calibration management software with the historanalysis option is a great help in making this type of analysis.

The cost of recalibration vs. consequences

of an out-of-tolerance situation

Optimizing between recalibration costs and the consequences of an ou

of-tolerance situation is important. In critical applications, the costs o

an out-of-tolerance situation can be extremely high (e.g. pharmaceutic

applications) and therefore calibrating the equipment more often

safer. However, in some non-critical applications, where the out-o

tolerance consequences are not serious, calibration can be made les

frequently. Therefore, evaluating of the consequences of an out-o

tolerance situation is something to be considered. The corrective action

in such a case should also be made into an operating procedure.

Some measurements in a factory typically have more effect on

product quality than others, and therefore some measurements ar

more acute than others and should be also calibrated more often tha

others.

Initial calibration period

When you purchase calibration equipment with which you are no

familiar, you still need to decide the initial calibration period. In th

In critical applications,

the costs of an out-

of-tolerance situation

can be extremely high

(e.g. pharmaceuticalapplications) and therefore

calibrating the equipment

more often is safer.



99

situation, abiding by the manufacturer’s recommendation is best. For

more acute applications, using a shorter calibration period right from

the beginning is recommended.

Other things to be consideredThere are also other issues to be considered when determining

the calibration period, such as the workload of the equipment,

the conditions where the equipment will be used, the amount of

transportation and is the equipment look damaged.

In some cases, crosschecking with other similar measuring

equipment is also feasible for detecting the need for calibration.

Crosschecking may be carried out before every measurement in some

acute applications.

Naturally, only appropriate, metrological, responsible personnel

in the company may make changes to the calibration equipment’s

calibration period.

In some cases,

crosschecking with

other similar measuring

equipment is also feasible

for detecting the needfor calibration.

SUMMARY

The main issues to be considered when determining the

calibration period for measuring equipment should include at

least following:

• The uncertainty needs of the measurements

to be done.

• The stability history of the measuring equipment.

• Equipment manufacturer’s recommendations.

• The risk and consequences of an out-of-tolerance situation.

• Acuteness of the measurements.



101

Paper is part of our everyday lives – whether in the workplace or

at home. Take a minute to look around the room you are in and

you’ll notice how many objects are made from paper: books,

magazines, printer paper, perhaps even a poster on the wall.

Global consumption of paper has grown 400% in the last 40 years.Today, almost 4 billion trees or 35% of the total trees cut down across

the world are used in paper industries on every continent (source: www.

ecology.com).

So let’s not add to this already heavy burden on our forests and

the environment. As manufacturing companies, our consumption of

paper is far higher than it needs to be, especially given that there are

technologies, software and electronic devices readily available today

which render the use of paper in the workplace unnecessary.

Other than helping to save our planet and reducing the number of

trees cut down each year, as businesses, there are other, significant

benefits in minimising the use of paper.

Take the calibration of plant instrumentation devices such as

temperature sensors, weighing instruments and pressure transducers.

Globally, amongst the process manufacturing industries, calibrating

instruments is an enormous task that consumes vast amounts of

paperwork. Far too many of these companies still use paper-based

calibration systems, which means they are missing out on the benefits

of moving towards a paperless calibration system.

Traditional paper-based calibration systems

Typically, a paper-based calibration system involves the use of hand-

written documents. Whilst out in the field, a maintenance or service

Paperless calibration improves

quality and cuts costs

Far too many of these

companies still use

paper-based calibration

systems, which means

they are missing out on

the benefits of moving

towards a paperless

calibration system.



102

engineer will typically use a pen and paper to record instrumen

calibration results. On returning to the office, these notes are the

tidied up and/or transferred to another paper document, after whic

they are archived as paper documents.

While using a manual, paper-based system requires little or n

investment in new technology or IT systems, it is extremely labouintensive and means that historical trend analysis of calibration resul

becomes very diff icult. In addition, accessing calibration data quickl

is not easy. Paper systems are time consuming, they soak up lots o

company resources and manual (typing) errors are commonplace. Du

effort and the re-keying of calibration data into multiple database

become significant costs to the business.

These same companies that use paper-based calibration system

are together generating hundreds of thousands (millions?) of pape

calibration certificates each year. However, by utilising the lates

software-based calibration management systems from companie

like Beamex, these organisations can signif icantly reduce their papconsumption, whilst also improving quality, workflow and makin

other significant cost savings for the business.

Practical benefits of using less paper

Aside from the financial benefits of moving towards a paperles

calibration system, there are practical reasons why firms should g

paperless. Often, in industrial environments, it is not practicable t

store or carry lots of paperwork. After all, every square foot of th

business has an associated cost.

Furthermore, important paper records could potentially be lo

or damaged in an accident or fire. So why would these companie

generate and store separate paper copies of important records such a

works orders, standard operating procedures (SOPs), blank calibratio

certificates, etc. when these records can all be combined into a sing

electronic record?

Improved workflow

With paper-based systems, paper records that need approval have to b

routed to several individuals, which is time-consuming. With paperles

systems, workflow improves dramatically. There will be less waitin

time, as those individuals who need to sign off records or calibratio

With paperless

systems, workflow

improves dramatically.



103

Paperless calibration

systems improve plant

efficiencies because the

entire calibration process

is now streamlined and

automated.

documents can share or access electronic records simultaneously from

a central database. The cost and time associated with printing copies

of paper documents is also eliminated, as well as the cost of filing and

storing those paper records.

Just as important, electronic records enable easier analysis of data,

particularly calibration results. Historical trending becomes easier,faster and more reliable, which again has cost reduction benefits to the

business. Calibration intervals can be optimised. For example, those

instruments that are performing better than expected may well justify

a reduction in their calibration frequency.

When a plant is being audited, calibration software facilitates both

the preparation and the audit itself. Locating records and verifying

that the system works becomes effortless when compared to traditional

paper-based record keeping. Paperless calibration systems improve

plant efficiencies because the entire calibration process is now

streamlined and automated. Costly production downtime due to

unforeseen instrument failures will also be reduced.

Data integrity

The integrity of paper-based calibration systems cannot be relied

upon. Paper records may not always reflect the truth. For example,

manual errors such as misreadings can occur, particularly when using

weighscales or other instruments that are open to an individual’s

own interpretation of the data. Sometimes users may inappropriately

modify the results data due to work pressures or lack of time/resources.

Illegible handwritten notes are also a problem, especially if these

paper records need to be typed or transcribed to a computer system

or database. Transcription errors such as these can lead to all sorts of

problems for a business and can take months to rectify or to identify

the rogue data.

Business benefits

For those more enlightened companies that use software-based

calibration systems, the business benefits are signif icant. The whole

calibration process – from initial recording of calibration data through

to historical trend analysis – will take less time, whilst mistakes and

manual errors will be virtually eliminated. In turn, this means that

operators, engineers and management will have more confidence in



104

the data, particularly when it comes to plant audits. In addition, th

greater confidence in calibration data leads to a better understandin

and analysis of business performance and KPIs (particularly if th

calibration software is integrated with other business IT systems suc

as a CMMS) leading to improved processes, increased efficiencies an

reduced plant downtime.

Commissioning

At plant commissioning times, electronic records simplif

the handover of plant and equipment. Although handover b

commissioning teams that use paper records is straightforward an

of universal format, electronic records are easy to manipulate and ca

be re-used in different IT systems. Electronic data also provides a

excellent foundation for ongoing plant operation and maintenance

without needing to collect all the plant data again.

How paperless should you go?

Of course, in reality, many companies are neither completely paperle

nor rely solely on paper-based systems – the process is sometime

a hybrid of the two. A key part of paperless calibration records i

the capture of data at point of work, often in difficult industria

environments that would make the use of portable off ice compute

impractical, and the manual entry of calibration results into un

intelligent calibration forms on portable industrial computers pron

to eye-to-hand data mis-reads and repetitive strain induced error. On

way to overcome these error prone data capture methods is to us

portable documenting calibrators to measure what can be measure

and provide intelligent, technician friendly interfaces on industrialize

PDA or tablet based hardware when manual data entry cannot b

avoided. The un-editable electronic data stored on high performanc

multifunction calibrators can be uploaded to calibration managemen

software for safe storage and asset management. Companies can g

even further than this and use electronic records for works order

business management systems, data historians, and for contro

systems. In other words, the calibration data is shared with othe

business IT systems electronically, resulting in completely paperles

end-to-end workf lows.

The calibration data

is shared with other

business IT systems

electronically, resulting

in completely paperless,

end-to-end workflows.



105

Suitable hardware

Rather than rely on engineers in the field accurately keying in

calibration results into suitably robust laptops or PDAs, it is better to

source the data electronically using documenting calibrators that are

specifically designed for this task.

Validation, training & education

Paperless systems also need validating in the user’s own environment.

Here, Beamex provides comprehensive validation, education and

training services for customers.

Education and training for users is critical, as this will help companies

to overcome the natural resistance to change amongst the workforce,

which may be used to dealing with traditional, paper-based systems.

Case study

Beamex is helping many organisations to implement paperless

calibration management systems, including Pharmaceuticals,

Chemicals, Power & Energy, Oil Gas & Petrochemicals companies.

Amongst these customers is UK firm Croda Chemicals Europe.

Based in East Yorkshire near Goole, the Croda plant uses pressurised

vessels to purify lanolin for healthcare and beauty products. Each

vessel needs to be certified at least once every two years in order

to demonstrate that the vessel is safe and structurally sound. This

includes a functionality check on all of the pressure instrumentation,

as well as the sensors that monitor the incoming chemical additives

and the outgoing effluent.

Senior Instrument Technician David Wright recalls what it was like

to perform all of those calibration operations with paper and pencil

during the company’s regularly scheduled maintenance shutdowns:

“It took us one week to perform the calibrations and a month to put

together the necessary paperwork.”

Today, Croda uses the CMX calibration management software

system from Beamex, which coordinates data collection tasks and

archives the results. “It’s faster, easier and more accurate than our old

paper-based procedures,” says Wright. “It’s saving us around 80 man-

hours per maintenance period and should pay for itself in less than

three years.”

Education and training

for users is critical, as

this will help companies

to overcome the natural

resistance to change

amongst the workforce,

which may be used to

dealing with traditional,

paper-based systems.



106



107

Calibration plays a vital role in process plant commissioning and

when installing new instruments. This article explains process

instrument commissioning and the benefits of calibration

during the commissioning phase.

What is process instrument commissioning?

Successful commissioning of process instrumentation is an essential

requirement for ideal plant performance. A plant, or any defined part

of a plant, is ready for commissioning when the plant has achieved

mechanical completion. Plant commissioning involves activities such

as checking to ensure plant construction is complete and complies with

the documented design or acceptable (authorized and recorded) design

changes. In general, commissioning activities are those associated with

preparing or operating the plant or any part of the plant prior to the

initial start-up and are frequently undertaken by the owner or joint

owner/ contractor team.

Commissioning may involve mock operations which are

commissioning activities conducted to allow operational testing

of the equipment and operator training and familiarization. At

the completion of commissioning, the plant will be fully ready for

production operation.

Energizing power systems, operational testing of plant equipment,

calibration of instrumentation, testing of the control systems as well as

verification of the operation of all interlocks and other safety systems

are also typical commissioning tasks. These activities are usually

described as ‘cold commissioning’.

Pre-commissioning activities are those which have to be undertaken

Intelligent commissioning

Successful commissioning

of process instrumentation

must be considered within

the context of the overall

commissioning program.



108

prior to operating equipment, such as adjustments and check

on machinery performed by the construction contractor prior t

commissioning and without which the installation cannot be said t

be mechanically complete. Mechanical completion of a plant or an

part of a plant occurs when the plant or a part of the plant has bee

completed in accordance with the drawings and specifications, and thre-commissioning activities have been completed to the extent wher

the owner approves the plant and can begin commissioning activitie

Commissioning requires a team of people with a background i

plant design, plant operation and plant maintenance. Some companie

employ specialized commissioning engineers. This can prove to be

worthwhile investment for large plants because it allows for dedicate

responsibility and focus in operations and signif icant improvements t

schedules, and adverse incidents at the start-up phase can be avoided

An extra day taken for commissioning means the same to the plan

owner as an extra day taken during designing or construction; in fact,

may cost more, as the plant owner’s commitments in terms of producmarketing and operational costs are likely to be higher.

Management, personnel and cost of commissioning

Since commissioning takes place toward the end of the project, ther

is a risk that the work may be under-resourced, because the funds hav

been allotted to cover budget overruns. It is essential to comprehen

the scope and length of commissioning activities and include them

in the initial project plan and budget allocations, and ensure th

commitment is maintained.

The cost of process instrument commissioning is typically affecte

by the following issues: learning and familiarizing with the field devic

physically installing the field device, connecting to and identifyin

the field device, configuring the required parameters and testing th

configuration and interface to other systems. Basically, these steps mu

be repeated with every field device that will be installed at the plant.

As there are many cost factors in the commissioning proces

detailed planning of commissioning and plant handover are essentia

elements of the overall project plan and schedule as any other groupin

of activities.

Each of the commissioning activities must be broken down into

number of manageable tasks, and a schedule needs to be establishe

for each task including benchmarks for monitoring purposes. The rat

There are many reasons

why instruments should

be calibrated during the

commissioning phase

before start-up.



109

of commissioning is measurable (e.g. number of loops or sequence

of steps tested per day), thereby enabling progress to be reviewed

regularly.

Successful commissioning of process instrumentation must be

considered within the context of the overall commissioning program.

Good planning, coordination, communications, documentation,

teamwork and training are all essential. The commissioning team

consists of a mixture of specialists, instrument and process engineers,

and the size of the team and composition of specialists depends on

the nature and scope of the system.

Calibration and the commissioning of field instrumentation

New process instrumentation is typically configured and calibrated by

the manufacturer prior to installation. However, instruments are often

recalibrated upon arrival at the site, especially if there has been obvious

Sequence of activities leading to commissioning and acceptance of a

plant.

Construction

Pre-commissioning

Mechanical completion

Commissioning

Trial operation

Initial start-up

Examine product specification

Examine production performance

Acceptance of plant

The calibration database

can be calibration

software designed

specifically for managing

calibration assets and

information, such as the

Beamex ® CMX Calibration

Software.



110

damage in transit or storage. There are also many other reasons wh

instruments should be calibrated during the commissioning phas

before start-up.

Assuring transmitter quality

First of all, the fact that an instrument or transmitter is new doenot automatically mean that it is within required specification

Calibrating a new instrument before installing or using it is a qualit

assurance task. You can check the overall quality of the instrument t

see if it is defective and to ensure it has the correct, specif ied setting

Reconfiguring a transmitter

The new uninstalled instrument or transmitter may have the correc

specified settings. However, it is possible that the original planne

settings are not valid anymore and they need to be changed. B

calibrating an instrument you can check the settings of the instrumen

After you have performed this task, it is possible to reconfigurthe transmitter, when the initial planned specifications have bee

changed. Calibration is therefore a key element in the process o

reconfiguring an uninstalled transmitter.

Monitoring the quality and stability of a transmitter

When calibration procedures are performed for an uninstalle

instrument, the calibration serves also future purposes. By calibratin

the transmitter before installation and on a regular basis thereafter,

is possible to monitor the stability of the transmitter.

Entering the necessary transmitter data into a calibration database

By calibrating an instrument before installation it is possible t

enter all the necessary instrument data into the calibration databas

as well as to monitor the instrument’s stability, as was explained i

the previous paragraph. The calibration database can be calibratio

software designed specifically for managing calibration assets an

information, such as the Beamex® CMX Calibration Software. Th

transmitter information is critical in defining the quality of th

instrument and for planning the optimal calibration interval of th

instrument. Transmitters that are found to be highly stable nee

not be recalibrated as often as transmitters that tend to drift. Th

trick is determining which sensors should be recalibrated after a few

hours, weeks, or years of operation and which can be left as is fo

The trick is determining

which sensors should be

recalibrated after a few

hours, weeks, or years

of operation and which

can be left as is for longer

periods without sacrificing

quality or safety.



111

longer periods without sacrificing quality or safety. Doing so allows

maintenance personnel to concentrate their efforts only where needed,

thereby eliminating unnecessary calibration work. Therefore, entering

the instrument data into a calibration management system is part of

the calibration procedures performed on an instrument before it is

installed and in use.

Integrated calibration solution by Beamex

The Beamex® Integrated Calibration Solution, consisting of calibration

software and documenting calibration equipment, improves the

quality and efficiency of the entire calibration system through faster,

smarter and more accurate management of all calibration assets and

procedures.

The Beamex® MC series documenting calibrators can be used for

calibrating pressure, temperature, electrical and frequency signals. The

Beamex calibrators support various different transmitter protocols,such as analog, HART, Foundation Fieldbus and Profibus. The Beamex

calibrators are all-in-one calibrators, which mean that they can be used

to replace several individual measurement devices. Intrinsically safe

calibrators for potentially explosive environments are also available.

The Beamex® CMX Calibration Software can be used for improving

the quality, productivity and cost-effectiveness of a plant’s calibration

process. The Beamex® CMX can be used for planning and scheduling

calibrations, managing and storing all calibration data as well as

analyzing and optimizing the calibration interval. Using the CMX

gives always a clear status of the transmitters; for instance, are they

installed and ready for calibration, does anyone perform the calibration

(check in/out function) and what is the instrument/position status

(pass/fail).

Having a fully integrated calibration management system – using

documenting calibrators and calibration management software

– is important. Beamex® CMX Calibration Software ensures

that calibration procedures are carried out at the correct time and

that calibration tasks do not get forgotten, overlooked or become

overdue. By using a documenting calibrator, the calibration results

are stored automatically in the calibrator’s memory during the

calibration process. Engineers performing calibrations no longer

have to write down any results on paper, making the entire process

much quicker and reducing costs. All calibration documentation is

Beamex ® CMX Calibration

Software ensures that

calibration procedures are

carried out at the correct

time and that calibration

tasks do not get forgotten,

overlooked or become

overdue.



112

therefore automatically produced when using the Beamex® Integrate

Calibration Solution. The quality and accuracy of calibration resul

also improve, as there are fewer mistakes due to human error. Th

calibration results are transferred automatically from the calibrator

memory to the computer/ database. This means that engineers do no

spend their time transferring the results from their notepad to finastorage on a computer; again, saving time and money.

Major time-savings can also be achieved by using Beamex

documenting MC calibrators HART and/or Fieldbus functionalit

to enter transmitter data into the calibrators’ memory where the dat

can be populated to the CMX Calibration Software, instead of typin

the data manually into the calibration database.

SUMMARY

Calibration is beneficial during process plant commissioning

for various different reasons:

• Transmitter quality assurance

• Reconfiguring a transmitter

• Monitoring the quality and stability of a transmitter

• Entering the necessary transmitter data into a calibration

database and defining the optimal calibration interval

By using a documenting

calibrator, the calibration

results are stored

automatically in the

calibrator’s memory

during the calibration

process.



113



114



115

For process manufacturers today, having a reliable, seamlessly

integrated set of IT systems across the plant, or across multiple

sites, is critical to business efficiency, profitability and growth.

Maintaining plant assets – whether that includes production line

equipment, boilers, furnaces, special purpose machines, conveyorsystems or hydraulic pumps – is equally critical for these companies.

Maintenance management has become an issue which deserves

enterprise-wide and perhaps multi-site attention, especially if the

company is part of an asset-intensive industry, where equipment and

plant infrastructure is large, complex and expensive. If stoppages

to production lines due to equipment breakdowns are costly,

implementing the latest computerized maintenance management

systems (CMMS) might save precious time and money.

In the process industries, a small, but critical part of a company’s

asset management strategy should be the calibration of process

instrumentation. Manufacturing plants need to be sure that their

instrumentation products – temperature sensors, pressure transducers,

flow meters and the like – are performing and measuring to specified

tolerances. If sensors drift out of their specification range, the

consequences can be disastrous, perhaps resulting in costly production

downtime, safety issues or batches of inferior quality goods being

produced, which then have to be scrapped. For this, Beamex’s

calibration management software, Beamex® CMX, has proved

itself time and time again across many industry sectors, including

pharmaceuticals, chemicals, nuclear, metal processing, paper, oil and

gas.

Successfully executing a system

integration project

In the process industries,

a small, but critical

part of a company’s

asset management

strategy should be the

calibration of process

instrumentation.



116

Seamless communication

Today, most process manufacturers use some sort of computerize

maintenance management system (CMMS) that sits alongsid

their calibration management system. Beamex® CMX Professiona

or Beamex® CMX Enterprise software can easily be integrated tCMM systems, whether it is a Maximo, SAP or Datastream CMM

system or even a company’s own, in-house software for maintenanc

management.

Beamex® CMX helps companies document, schedule, plan, analyz

and optimize their calibration work. Seamless communication betwee

CMX and ‘smart’ calibrators means that companies have the ability t

automate predefined calibration procedures. As well as retrieving an

storing calibration data, CMX can also download detailed instruction

for operation before and after calibrating, like procedures, reminde

and safety-related information. Seamless communication wit

calibrators also provides many practical benefits such as a reductioin paperwork, elimination of human error associated with manua

recording, and the ability to speed up the calibration task. CMX als

stores the complete calibration history of process instruments an

produces fully traceable calibration records.

Integrating CMX with a CMM system means that plant hierarch

and all work orders for process instruments can be generated an

maintained in the customer’s CMM system. Calibration wor

orders can easily be transferred to CMX Calibration Software. Then

once the calibration work order has been executed, CMX sends a

acknowledgement order of this work back to the customer’s CMM

system. All detailed calibration results are stored and available on th

CMX database.

Integration project

A customer may have a large CMM system and a considerable amoun

of data keying to perform before integration is complete. A dat

exchange module or interface that sits between the two systems i

required. The integration project involves three main parties: Beamex

the customer and the CMM system software partner.

Beamex ® CMX

Professional or Beamex ®

CMX Enterprise software

can easily be integrated

to CMM systems,

whether it is a Maximo,

SAP or Datastream

CMM system or even a

company’s own, in-house

software for maintenance

management.



117

Project organization and resourcing

In order to have a successful integration, it’s important that the right

people and decision-makers are involved and participate right from

the beginning of the project. It’s also essential that the main roles and

responsibilities of the parties are specif ied before the project evolves.Moreover, a project organization should be established and include

members from both the supplier’s and the customer’s organization,

as a successful project requires input from both parties. The role of

each member should be defined and project managers appointed. The

project manager is usually responsible for the operative management

of the project. In addition, a project steering group may need to be

established. The project steering group is responsible for making key

decisions during the project. The role, tasks and authority of the

project steering group must be defined as well as the decision-making

procedures.

Project phases

The integration project is divided into four main phases:

1. Scope of Work

2. Development and Implementation

3. Testing

4. Installation, Verification and Training

The four main phases are also often divided into sub-phases. A

schedule is usually defined for the completion of the entire project as

well as for the completion of each project phase. Each project phase

should be approved according to the acceptance procedures defined

in the offer, agreement, project plan or other document annexed to

the offer / agreement.

The integration project

involves three main

parties: Beamex, the

customer and the CMM

system software partner.



118

Scope of work

To ensure successful integration with a satisfied customer, definin

the correct scope of work (SOW) is crucial. The scope of work shoul

include a brief project description, services provided, main role

partner responsibilities and the desired outcome. The scope of wor

is important to make sure that both the supplier and the custome

have understood the project in question and they have simila

expectations from it. The SOW is often developed through pre-studie

and workshops.

Defining what is not included in the scope of work is just as importan

as defining what is included in it. This means that establishing som

framework and limitations for the project are also very importan

as the resourcing, scheduling and costs of the project depend greatl

on the scope of work. If the scope of work is not defined carefully

questions or problems may appear later in the project, which will direc

the project back to phase one where a review of the scope is necessary

This is an urgent but time-consuming matter and can be avoided

the right people and decision-makers participate in the first projec

phase. However, as changes to the original scope of work may b

necessary and required even in projects where the SOW phase ha

been done carefully, it is important that the supplier and custome

agree on change management procedures as early as the starting phas

of the project.



119

Development and implementation

When the scope of work has been defined and approved by both

parties, the integration can enter the next phase, which is the actual

development and implementation of the project deliverables.

Testing

Testing occurs both during the project after each partial delivery, in

order to be able to continue the development work to next phase, and

at the final stage of the project. The testing, approval procedures and

timelines should be defined when agreeing on the project.

Installation, verification and training

The final stage in the integration process is the installation and testing

at the customer’s facility and taking the system into production use.

The project manager at the buyer’s facility now plays a major role in

the success of the integration process. The supplier will, if requiredand agreed, assist with informing, training and providing training

materials.

When the integration is finished, the customer has a system that

saves time, reduces costs and increases productivity by preventing

unnecessary double effort and re-keying of procedures in separate

When the integration is

finished, the customer

has a system that saves

time, reduces costs and

increases productivity by

preventing unnecessary

double effort and re-

keying of procedures in

separate systems.INTEGRATION PROJECT PHASES

Specifications

documentation

• Purpose / needs

• Target• Supplier’s responsibilities• Customer’s responsibilities• Project management and

project steering group

• Change management

• Testing and acceptanceprocedures

• Final approval by customer

Implementationdocumentation

Testingdocumentation

Instructionaldocumentation

FOLLOW UPCLOSURE OF INTEGRATION PROJECT

Scope of

work (SOW)

Development

and

implementation

Testing

Ve n

Tr

Installation

rificatio

aining



120

systems. When there is no need to manually re-key the data, typin

errors are eliminated. A CMMS integration will enable the custome

company to automate its’ management with smart calibrators. Th

improves the quality of the entire system.

Integrating a CMM system with calibration management softwar

is an important step in the right direction when it comes to EAMEnterprise Asset Management. However, EAM is more than ju

maintenance management software. It’s about companies taking

business-wide view of all their plant equipment and coordinatin

maintenance activities and resources with other departments an

sites, particularly with production teams. Savings from EAM ar

reasonably well-documented and come in various guises, the mo

common benefits being: less equipment breakdowns (leading to

reduction in overall plant downtime); a corresponding increase i

asset utilization or plant uptime; better management of spare par

and equipment stocks; more eff icient use of maintenance staff; an

optimized scheduling of maintenance tasks and resources. But thkey to success is really the quality of information you put in th

software, the data has to be as close to 100% accurate as possible t

get maximum benefit from the system.

Integrating a CMM

system with calibration

management software

is an important step in

the right direction when it

comes to EAM, Enterprise

Asset Management.



121



Calibrationin Industrial

Applications



124



125

F

or process manufacturers, regular calibration of instruments

throughout a manufacturing plant is common practice. In plant

areas where instrument accuracy is critical to ensure product

quality, safety or custody transfer, calibration every six months – oreven more frequently – is not unusual.

However, the key final step in any calibration process – documentation

– is often neglected or overlooked because of a lack of resources, time

constraints or the pressure of everyday activities. Indeed, many process

plants are under pressure to calibrate instruments quickly but accurately

and to ensure that the results are then documented for quality assurance

purposes and to provide full traceability.

The purpose of calibration itself is to determine how accurate an

instrument or sensor is. Although most instruments are very accurate

these days, regulatory bodies often need to know just how inaccurate a

particular instrument is and whether it drifts in and out of a specified

tolerance over time.

What is a documenting calibrator?

A documenting calibrator is a handheld electronic communication

device that is capable of calibrating many different process signals

such as pressure, temperature and electrical signals, including

frequency and pulses, and then automatically documenting the

calibration results by transferring them to a fully integrated calibration

management software. Some calibrators can read HART, Foundation

Fieldbus or Profibus output of the transmitters and can even be used

for configuring ‘smart’ sensors.

The benefits of usinga documenting calibrator

Many process plants

are under pressure to

calibrate instrumentsquickly but accurately and

to ensure that the results

are then documented

for quality assurance

purposes and to provide

full traceability.



126

Heikki Laurila, Product Manager at Beamex in Finland comment

“I would define a documenting calibrator as a device that has the dua

functionality of being able to save and store calibration results in i

memory, but which also integrates and automatically transfers thi

information to some sort of calibration management software.”

A non-documenting calibrator is a device that does not store dator stores calibration data from instruments but is not integrated to

calibration management system. Calibration results have to be keye

manually into a separate database, spreadsheet or paper filling system

Why use a documenting calibrator?

By using a documenting calibrator, the calibration results are store

automatically in the calibrator’s memory during the calibratio

process. The engineer does not have to write any results down o

paper, which makes the entire process much faster and consequentl

reduces costs. The quality and accuracy of calibration results will alsimprove, as there will be fewer mistakes due to human error.

The calibration results are automatically transferred from th

calibrator’s memory to the computer/database. This means th

engineer does not have to spend time transferring the results from h

notepad to final storage on a computer; again, saving time and mone

With instrument calibration, the calibration procedure itself

critical. Performing the calibration procedure in the same way eac

time is important for the consistency of results. With a documentin

calibrator, the calibration procedure can be automatically transferre

from the computer to the handheld calibrator before going out int

the field.

As Laurila states, “Engineers, who are out in the field performin

instrument calibrations, receive instant pass or fail messages with

documenting calibrator. The tolerances and limits for a sensor, a

well as detailed instructions on how to calibrate the transmitter, ar

entered once into the calibration management software and the

downloaded to the calibrator. This means calibrations are carried ou

in the same way every time because the calibrator tells the enginee

which test point he needs to measure next. Also, having an easy-to

use documenting calibrator is definitely the way forward, especiall

if calibration is one of the many tasks that the user has to carry out i

his daily maintenance routine.”

With a multi-functioning documenting calibrator, such as th

The engineer does

not have to write any

results down on paper,

which makes the entire

process much faster and

consequently reduces

costs.



127

Beamex® MC5 or MC6, the user doesn’t need to carry as much

equipment while out in the field. Both calibrators can be used also

to calibrate, configure and trim HART, Foundation Fieldbus H1 or

Profibus PA transmitters.

Laurila continues, “With a documenting calibrator, such as the

MC5 or the MC6, the user can download calibration instructions forhundreds of different instruments into the device’s memory before

going out into the field. The corresponding calibration results for

these instruments can be saved in the device without the user having

to return to his PC in the off ice to download/upload data. This means

the user can work in the f ield for several days.”

Having a fully integrated calibration management system – using

documenting calibrators and calibration management software –

is important. Beamex® CMX Calibration Software ensures that

calibration procedures are carried out at the correct time and that

calibration tasks are not forgotten, overlooked or overdue.

Benefits in practice

Conventional calibration work relies on manual, paper-based

systems for documenting. Manual calibration takes more time and

is more prone to error. Oftentimes, the f ield engineer calibrates the

instrument, handwrites the results onto a paper form and then re-

enters this information into a database when he returns to the office.

Unintentional errors often occur and the whole process is time-

consuming.

Using Beamex® CMX Calibration Software and the documenting

Beamex® MC6 or MC5 Multifunction Calibrators provides full

control of the entire calibration process and reduces costs by up

to 50 %.* Why? Because the devices provide higher accuracy, the

calibration process is much faster, and the system provides full

traceability. When you’ve got to calibrate instruments throughout a

site, typically with five-point checks on each instrument, speed and

accuracy are critical. Using the MC6 or MC5 with CMX software

means that calibration instructions for an instrument and calibration

orders are downloaded to the calibrators and ready to guide the

engineer in the field with correct calibration procedures.


ensures that calibration

procedures are carried out

at the correct time and that

calibration tasks are not

forgotten, overlooked or

overdue.

___________________* Reported to the Industrial Instrumentation and Controls Technology Alliance and presented

at the TAMU ISA Symposium, January, 2004



128

After completing instrument calibrations, the system provides

full quality assurance report of all instruments calibrated along with

required calibration certif icate. This not only ensures full traceabilit

but also ref lects full and traceable documentation of the complete

work.

Calibration results are

automatically transferred

from the calibrator’s

memory to a computer or

fully integrated calibration

management system.

SUMMARY

The benefits of using a documenting calibrator

• Calibration results are automatically stored in the

calibrator’s on-board memory during the calibration

procedure.

• Calibration results are automatically transferred from the

calibrator’s memory to a computer or fully integrated

calibration management system.

• Less paperwork and fewer manual errors.

• Reduced costs from a faster and more efficient calibration

process.

• Improved accuracy, consistency and quality of calibration

results.

• A fully traceable calibration system for the entire plant.

• The calibration procedure itself is guided by the calibrator,

which uploads detailed instructions from the computer or

calibration management software.

• No manual printing or reading of calibration instructions is

required; again, saving time and money and simplifying the

process.



129



131

From the point of view of the owner, weighing instruments, usually

called scales or balances, should provide the correct weighing

results. How the weighing instrument is used and how reliable the

weighing results are can be very different. Using weighing instruments

for legal purposes must have legal verification. If a weighing instrument is used in a quality system, the user must

define the measurement capability of it. In any case, it is the owner

or the user of the instrument that carries the final responsibility of

measurement capability and who is also responsible for the processes

involved. (S)He must select the weighing instrument and maintenance

procedure to be used to reach the required measurement capability.

From a regulatory point of view, the quality of a weighing instrument

is already defined in OIML regulations, at least in Europe. Calibration

is a means for the user to obtain evidence of the quality of weighing

results, and the user must have the knowledge to apply the information

achieved through calibration.

Calibration and legal verification

Weighing instruments may also possess special features. One of these

features includes making measurements for which legal verification is

required, for example when invoicing is based on the weight of a solid

material. The features may vary slightly from country to country, but

in the EU they are the same, at least at the stage when the weighing

instrument is being introduced into use.

Verification and calibration abide by a different philosophy.

Calibration depicts the deviation between indication and reference

(standard) including tolerance, whereas verification depicts the

Calibration of weighing instruments

Part 1

In any case, it is the

owner or the user of

the instrument that carries

the final responsibility

of measurement

capability and who is

also responsible for the

processes involved.



132

maximum permissible amount of errors of the indication. This is

feasible practice for all weighing. The practical work for both method

is very similar and both methods can be used to confirm measuremen

capability, as long as legal verification is not needed. The terminolog

and practices used previously for verifying measurement capability

and for weighing technology in general, are based on these practices ocalibrating and verifying, even if it was a question of general weighin

(non-legal).

Confirmation is the collecting of information

Confirming the capability of weighing instruments should happe

by estimating the quality of the measuring device in the place wher

it will be used. In practice, this means investigating the efficiency o

the weighing instrument; this operation is known as calibration (o

verification). One calibration provides information on a temporar

basis and a series of calibrations provides time-dependent informationThe method of calibration should be selected such that it provide

sufficient information for evaluating the required measuring toleranc

The method should be precise for achieving comparable results durin

all calibrations.

Comparing the indication of weighing instruments with a se

standard gives the deviation or error. However, to be able to define th

measuring tolerance, we need more information about the weighin

instrument, such as repeatability, eccentric load, hysteresis, etc. W

must remember that the quality of the evaluation of measurin

tolerance depends on the collected information through calibration

Using a calibration program, which goes through the same steps fo

every calibration – calculates deviation and measuring tolerance, and,

necessary, produces a calibration certif icate – is the best way to achiev

reliable information to use in comparisons. This type of program

is able to store all the history of calibrated weighing instrument

including information for other measuring devices. It is also hand

for monitoring measuring systems. The most important aspect of

calibration program is that it allows the user to select the calibratio

method that corresponds to the required level of measuring toleranc

and it displays the history of calibrations and in this way provide

the user with comprehensive information concerning measurin

capability.

We must remember

that the quality of the

evaluation of measuring

tolerance depends on

the collected information

through calibration.



133

The purpose of calibration and complete confirmation

Calibration is a process where the user is able to confirm the correct

function of the weighing instrument based on selected information.

The user must define the limits for permitted deviation from a true

value and required measuring tolerance. If these values are exceeded,an adjustment or maintenance is necessary.

Calibration itself, however, is a short-term process; the idea is that

the weighing instrument remains in good working condition until the

next calibration. For this reason, the user must determine all of the

external factors which may influence the proper functioning of the

weighing instrument. The factors in question may include the effect

of the environment where the weighing instrument is used and how

often the instrument needs to be cleaned, regular monitoring of the

zero point and the indication number with a constant mass.

Today, the function of weighing instruments, as well as many

other instruments, is based on microprocessors. They possess severalpossibilities for adjusting parameters in measuring procedures.

Calibration should be carried out using settings based on the

parameters for normal use. It is very important that the users of the

weighing instruments, as well as calibration personnel, are familiar

with these parameters and use them as protocol. Since there are several

parameters in use, it is important to always have the manual for using

the weighing instrument easily available to the user.

The content of the calibration certificate

Very often the calibration certificate is put on file as evidence of a

performed calibration to await the auditing of the quality system.

However, a quality system is usually concerned with the traceability

of measurements and the known measuring tolerance of the

measurements made. The calibration certif icate of a single measuring

device is used as a tool for evaluating the process of measuring tolerance

and for displaying the traceability of the device in question.

Performing calibrations based on the measuring tolerance is better

than doing routine measuring. Therefore, the user must evaluate

the process of measuring tolerance and compare this value with the

required measuring tolerance of the process.

Calibration itself, however,

is a short-term process;

the idea is that the

weighing instrument

remains in good working

condition until

the next calibration.



134

SUMMARY

Calibration (or verification) is a fundamental tool for

maintaining a measuring system. It also assists the user in

obtaining the required quality of measurements in a process.

The following must be taken into consideration:

• the type of procedure to be applied in confirming measuring

tolerance

• the interpretation of information while abiding by the

calibration certificate

• changing procedures based on received information

Quality calibration methods and data handling systems offer

state-of-the-art possibilities to any company.



135



137

Weighing is a common form of measurement in commerce,

industries and households. Weighing instruments are

often highly accurate, but users, i.e. their customers and/or

regulatory bodies, often need to know just how inaccurate a particular

scale may be. Originally, this information was obtained by classifyingand verifying the equipment for type approval. Subsequently, the

equipment was tested or calibrated on a regular basis.

Typical calibration procedures

Calibrating scales involves several different procedures depending

on national- and/or industry-specific guidelines or regulations, or on

the potential consequences of erroneous weighing results. One clear

and thorough guide is the EA-10/18, Guidelines on the Calibration

of Non-automatic Weighing Instruments, which was prepared by

the European Co-operation for Accreditation, and published by the

European Collaboration in Measurement and Standards (euromet).

Typical scale calibration involves weighing various standard weights

in three separate tests:

• repeatability test

• eccentricity test

• weighing test (test for errors of indication)

In the pharmaceutical industry in the United States, tests for

determining minimum weighing capability are also performed.

Repeated weighing measurements provide different indications

Usually, the object being weighed is placed on the load receptor

and the weighing result is read only once. If you weigh the object

Calibration of weighing instruments

Part 2

Weighing instruments are

often highly accurate, butusers, i.e. their customers

and/or regulatory bodies,

often need to know just

how inaccurate a particular

scale may be.



138

repeatedly, you will notice slight, random variation in the indication

The repeatability test involves weighing an object several times t

determine the repeatability of the scale used.

Center of gravity mattersThe eccentricity test involves placing the object being weighed in th

middle of the load receptor as accurately as possible. This is sometime

diff icult due to the shape or construction of the object being weighed

Typical calibration procedures include the eccentricity test. You ca

determine how much the eccentricity of the load will affect th

indication on the scale by weighing the same weight at the corners o

the load receptor.

Test for errors in indication

The weighing test examines the error of the indication on the scale foseveral predefined loads. This enables you to correct the errors an

definitions for non-linearity and hysteresis.

If the scale’s maximum load limit is extremely large, it may b

impractical to use standard weights for calibrating the entire range

In such a case, suitable substitution mass is used instead. Substitutio

mass should also be used if the construction of the scale does not allo

the use of standard weights.

A truck scale is unsuitable for weighing letters

The purpose of the minimum weight test is to determine the minimum

weight, which can be assuredly and accurately measured using th

scale in question. This condition is met if the measurement error

less than 0.1% of the weight, with a probability of 99.73%.

Combined standard uncertainty of the error U(E)

Knowing the error of the scale indication at the point of eac

calibration is not sufficient. You must also know how certain you ca

be about the error found at each point of calibration. There are severa

sources of uncertainty of the error, e.g.:

Weighing instruments are

often highly accurate, but

users, i.e. their customers

and/or regulatory bodies,

often need to know just

how inaccurate a particular

scale may be.



139

• The masses of the weights are only known with a certain uncertainty.

• Air convection causes extra force on the load receptor.

• Air buoyancy around the weights varies according to barometric

pressure, air temperature and humidity.

• A substitute load is used in calibrating the scale.

• Digital scale indications are rounded to the resolution in use.• Analogous scales have limited readability.

• There are random variations in the indications as can be seen in the

Repeatability Test.

• The weights are not in the exact middle of the load receptor.

The values of uncertainty determined at each point of calibration are

expressed as standard uncertainties (coverage probability: 68.27%),

which correspond to one standard deviation of a normally distributed

variable. The combined standard uncertainty of the error at a certain

point of calibration has a coverage probability of 68.27% as well.

Example: The calibration error

and its uncertainty at the

calibration point of 10 kg may

be expressed e.g. E = 2.5 g

and u(E) = ±0.7 g, which means

that the calculated error in the

indication is 2.5 g and the actual

error, with a coverage probability

of 68.27%, is between is between

1.8 g and 3.2 g.

±u(E)

68.27%

U(E) = 2u(E)95.45 %

2.5 g

3.2 g

3.9 g1.1 g

1.8 g

U(E) = 3u(E)99.73 %

0.4 g 4.6 g



140

Expanded uncertainty in calibration U(E)

In practice, a coverage probability of 68.27% is insuff icient. Normall

it is extended to a level of 95.45% by multiplying it with the coverag

factor k = 2. If the distribution of the indicated error cannot b

considered normal, or the reliability of the standard uncertainty valuis insuff icient, then a larger value should be used for the k-factor.

If you are able to use the k = 2 coverage factor, then the error an

its extended uncertainty at the point of calibration are E = 2.5 g an

U(E) = ±1.4 g. This means that the calculated error of the indicatio

is 2.5 g and the actual error, with a coverage probability of 95.45%,

between 1.1 g and 3.9 g.

Uncertainty of a weighing result

The purpose of calibration is to determine how accurate a weighin

instrument is. As the above-mentioned case indicates, you know thaif you repeat the calibration several times, the indication of weighin

an object of 10 kilograms will be between 10.0011 kg and 10.0039 k

95.45% of the time. However, the uncertainty of the results of late

routine weighings is usually larger. Typical reasons for this are:

• Routine weighing measurements involve random loads, whil

calibration is made at certain calibration points.

• Routine weighing measurements are not repeated whereas indication

received through calibrations may be averages of repeated weighin

measurements.

• Finer resolution is often used in calibration.

• Loading/unloading cycles in calibration and routine weighing ma

be different.

• A load may be situated eccentrically in routine weighing.

• Tare balancing device may be used in routine weighing.

• The temperature, barometric pressure and relative humidity of th

air may vary.

• The adjustment of the weighing instrument may have changed.

Standard and expanded uncertainties of weighing results are calculate

using technical data of the weighing instrument, its calibration result

knowledge of its typical behaviour and knowledge of the conditions o

the location where the instrument is used. Defining the uncertaint

of weighing results is highly recommended, at least once, for a

The purpose of calibration

is to determine how

accurate a weighing

instrument is.



141

typical applications and always for critical applications. Calculating

the uncertainty of weighing results assists you in deciding whether

or not the accuracy of the weighing instrument is sufficient and how

often it should be calibrated. However, determining the uncertainty

of weighing results is not part of calibration.

Calibrating and testing weighing instruments using CMX

CMX’s scale calibration enables you to uniquely configure calibration

and test each weighing instrument. Correspondingly, copying

configurations from one scale to another is easy. Error limits can be set

according to OIML or Handbook-44. Wide variation in user-specific

limits is also possible.

CMX calculates combined standard uncertainty and expanded

uncertainty at calibration of the weighing instrument. It allows you

to enter additional, user-defined uncertainty components in addition

to supported uncertainty components. CMX’s versatile calibrationcertificate and possibility to define a user specific certificate assure

that you can fulfill requirements set for your calibration certificates.

CMX’s scale calibration

enables you to uniquely

configure calibration

and test each weighing

instrument.



142



143

The most commonly and most frequently measurable variable in

industry is temperature. Temperature greatly inf luences many

physical features of matter, and its influence on e.g. quality,

energy consumption and environmental emission is significant.

Temperature, being a state of equilibrium, makes it different fromother quantities. A temperature measurement consists of several

time constants and it is crucial to wait until thermal equilibrium is

reached before measuring. Metrology contains mathematic formulas

for calculating uncertainty. The polynoms are specified in ITS 90 table

(International Temperature Scale of 1990). For each measurement,

a model that includes all inf luencing factors must be created. Every

temperature measurement is different, which makes the temperature

calibration process slow and expensive.

While standards determine accuracy to which manufacturers

must comply, they nevertheless do not determine the permanency of

accuracy. Therefore, the user must be sure to verify the permanency of

accuracy. If temperature is a significant measurable variable from the

point of view of the process, it is necessary to calibrate the instrument

and the temperature sensor. It is important to keep in mind an old

saying: all meters, including sensors, show incorrectly, calibration will

prove by how much.

Temperature sensors

The most commonly used sensors in the industry used for measuring

temperature are temperature sensors. They either convert temperature

into resistance (Resistance Temperature Detectors, RTD) or convert

temperature into low voltage (Thermocouples, T/C). RTD’s are based

Calibrating temperature instruments

While standards

determine accuracy to

which manufacturers

must comply, they

nevertheless do

not determine the

permanency of accuracy.



144

on the fact that the resistance changes with temperature. Pt100 is

common RTD type made of platinum and its resistance in 0 ̊ C (32 ̊ F

is 100 . Thermocouple consists of two different metal wires connecte

together. If the connections (hot junction and cold junction) ar

at different temperatures, a small temperature dependent voltag

difference/current can be detected. This means that the thermocoupis not measuring the temperature, but the difference in temperatur

The most common T/C type is the K-type (NiCr/NiAl). Despite the

lower sensitivity (low Seebeck coefficient), the noble thermo-elemen

S-, R- or B-type (PtRh/Pt, PtRh/Pt/Rh) are used especially in hig

temperatures for better accuracy and stability.

Temperature transmitters

The signal from the temperature sensor cannot be transmitted

longer distance than the plant. Therefore, temperature transmitter

were developed to convert the sensor signal into a format that cabe transmitted easier. Most commonly, the transmitter converts th

signal from the temperature sensor into a standard ranging between

and 20 mA. Nowadays, transmitters with a digital output signal, suc

as Fieldbus transmitters, are also being adopted, while the transmitte

converts the sensor signal, it also has an impact on the total accuracy

and therefore the transmitter must be calibrated on regular basi

A temperature transmitter can be calibrated using a temperatur

calibrator.

Calibrating temperature instruments

To calibrate a temperature sensor, it must be inserted into a know

temperature. Sensors are calibrated either by using temperatur

dry blocks for industrial field or liquid baths (laboratory). To mak

comparisons, we compare the sensor to be calibrated and the referenc

sensor. The most important criterion in the calibration of temperatur

sensors is how accurate the sensors are at the same temperature.

The heat source may also have an internal temperature measuremen

that can be used as reference, but to achieve better accuracy an

reliability, an external reference temperature sensor is recommended

The uncertainty of calibration is not the same as the accurac

of the device. Many factors influence the total uncertainty, an

performing calibration is not the least influencing factor. All hea

The most important

criterion in the calibration

of temperature sensors

is how accurate the

sensors are at the same

temperature.



146

The calibration of instruments and sensors must be performe

periodically. The ISO quality control system presupposes the qualit

control of calibration, the calibration of instruments effectin

production, regular calibration of sensors and traceable calibratio

as well as calibration documentation. The level of performance

calibration device needs to have depends on the accuracy requiremendetermined by each company. However, the calibration device mu

always be more accurate than the instrument or sensor being calibrated

Calibration of instruments and sensors can be carried out either o

site or in a laboratory.

Integrated calibration solution – a smarter way to calibrate

temperature

Beamex has introduced a smarter, more efficient and accurate solutio

for calibrating temperature. It is a complete solution for temperatur

calibration with various products and services, such as a series of highquality dry blocks for field and laboratory use, smart reference probe

and temperature calibration laboratory services.

“The temperature products and services we are now introducin

form an integral part of the Beamex® Integrated Calibration Solution

a complete calibration solution that enables faster, more accurate an

efficient management of all calibration assets and procedures”, say

Raimo Ahola, CEO of Beamex Group.

The Beamex® Integrated Calibration Solution concept is th

combination of calibrator, calibration software and PC for onlin

calibration. The instrument to be calibrated is connected to th

calibrator controlled by a computer, where the computer control

the calibration event. The Beamex® FB and MB dry blocks ar

part of the Beamex® Intergrated Calibration Solution. The dr

blocks communicate with the Beamex documenting multifunctio

calibrators enabling fully automated temperature calibration an

documentation. The calibration results can then be uploaded from th

documenting calibrators to the Beamex® CMX Calibration Software

The instrument’s calibration information is saved in the calibrato

and History Trend reports, both in numeric and in graphic form

“This helps the client to follow the condition of the instrument, whic

is useful in making decisions about purchasing new instrument

determining service in advance and recalibration. With the CM

Software, you can print out a calibration report as well as a traceabl

However, the calibration

device must always be

more accurate than the

instrument or sensor

being calibrated.



147

accredited calibration certif icate. Our integrated calibration solution

concept saves valuable time, eliminates any errors related to manual

entry and assures repeatable calibration procedures”, Mr Ahola adds.

The Beamex ® Integrated

Calibration Solution

concept is the

combination of calibrator,

calibration software and

PC for online calibration.



148



149

This article will discuss the various uncertainty components related

to temperature calibration using a temperature dry-block. It will

also present how to calculate the total uncertainty of a calibration

performed with a dry block.

What is a temperature dry block?

A temperature dry block consists of a heatable and/or coolable metallic

block, controller, an internal control sensor and optional readout

for external reference sensor. This article will focus on models that

use interchangeable metallic multi-hole inserts. There are fast and

lightweight dry blocks for industrial field use as well as models that

deliver near bath-level stability in laboratory use. There are also some

work safety issues that favor dry blocks in preference to liquid baths.

For example, in temperatures above 200 °C liquids can produce

undesirable fumes or there may be f ire safety issues. If a drop of water

gets into hot silicon oil, it could even cause a small steam explosion

which may splash hot oil on the user. Dry blocks are almost without

exception meant to be used dry. Heat transfer fluids or pastes are

sometimes used around or inside the insert, but they don’t necessarily

improve performance. They may actually even impede the dry block’s

performance and damage its internal components.

EURAMET

The EURAMET guideline (EURAMET /cg-13/v.01, July 2007

[previously EA-10/13]):

• The Euramet calibration guide defines a normative way to calibrate

Calculating total uncertaintyof temperature calibration with a dry block

There are fast and

lightweight dry blocks for

industrial field use as well

as models that deliver

near bath-level stability in

laboratory use.



150

dry blocks. As most of the manufacturers nowadays publish the

product specifications including the main topics in the Euramet guide

the products are easier to compare.

• Main topics in the EURAMET guideline include:

– Display accuracy – Axial uniformity

– Radial uniformity

– Loading

– Stability over time

– Hysteresis

– Sufficient immersion (15 x diameter)

– Stem loss for 6 mm or greater probes

– Probe clearance

(<= 0,5 mm at –80…660 °C)

(<= 1,0 mm at +660…1 300 °C)

Related uncertainty components

Uncertainty components that are related to temperature calibration ar

relevant to all manufacturers’ dry blocks. Some manufacturers specif

these components and some do not.

It is possible to use a dry block with the block’s internal measuremen

as the reference (true value), or to use an external reference temperatur

probe inserted in the block as a reference measurement.

Internal measurement as reference

When using a dry block’s internal measurement as reference, th

following uncertainty components should be taken into account:

• Display accuracy (a ccuracy of the internal measuremen

It is important to remember that all of the thermometers base

on thermal contact measure their own temperature. With dr

blocks, the internal control sensor is typically located inside th

actual block, whereas the probes to be calibrated are immerse

in the insert. There is always thermal resistance between th

internal sensor and the probes inside the insert and other source

of uncertainty need to be considered.

The Euramet calibration

guide defines a normative

way to calibrate dry

blocks.



151

• Axial uniformity

Axial uniformity refers to the variation in temperature along

the vertical length of the insert. The Euramet calibration guide

states, “dry wells should have a zone of sufficient temperature

homogeneity of at least 40 mm in length” at the bottom of the

insert. The purpose of this homogenous measurement zone is to

cover various sensor constructions. The thermocouple typically

has its “hot junction” close to the tip of the probe whereas the PRT

sensing element may be 30 to 50 mm long. With this in mind, a

homogenous zone of at least 60 mm is recommended.

• Radial uniformity

Radial uniformity refers to the variation in temperature between

the holes of the insert. Related uncertainty is caused, for example,

by the placement of the heaters, thermal properties of materials

and alignment of the insert holes. Non-symmetrical loading or

probes with significantly different thermal conductivity (for

example large diameter probes) may cause additional temperature

variation.

MAIN PARTS OF THE DRY BLOCK

Stem conductance

Sensor to becalibrated

Reference sensor

Axial uniformity

Internal sersor Radial uniformity

Uncertainty components

that are related to

temperature calibration

are relevant to all

manufacturers’ dry

blocks.



152

• Loading effect

Every probe in the insert conducts heat either from or into th

insert. The more the load, the more the ambient temperatur

will affect the measurements. Sufficient immersion depth an

dual zone control helps to reduce load-related uncertainties. Th

loading effect is not visible in the control sensor indication and thcontroller cannot completely compensate for this shift.

• Stability over time

– Stability describes how well the temperature remains the sam

during a given time.

– The Euramet calibration guide defines stability as a temperatur

variation over a 30-minute period, when the system has reache

equilibrium.

• Immersion

Sufficient immersion is important in any temperature measuremenThe Euramet calibration guide states that the immersion dept

should be at least 15 x the probe’s outer diameter. To minimiz

the stem conduction error it’s recommended, as a rule of thumb

to use immersion depth of 20 x the diameter, plus the length o

the sensing element. As the probe constructions vary greatly (shee

material, wall thickness, lead wire thermal conductivity etc.), a te

for each individual probe type to be calibrated should be made

If sufficient recommended immersion cannot be reached, the

the uncertainty caused by the insufficient immersion should b

estimated/ evaluated.

• Hysteresis

Hysteresis causes the internal sensor to be dependent on its previou

exposure. This means that the temperature of the dry block ma

be a bit different depending on the direction from which the se

point is approached. The hysteresis is greatest at the mid-point an

is proportional to the temperature range.

The specifications for the above uncertainty components should be i

the block’s specifications. If some component has not been specified,

should be estimated or evaluated.

Stability describes how

well the temperature

remains the same during

a given time.



153

Using an external reference sensor as reference

Unlike using the dry block’s internal sensor as a reference, the external

reference sensor is inside the insert together with the probes to be

calibrated. Therefore, the external reference enables more accurate

measurement of the temperature of the probes to be calibrated. Usingan external reference sensor enables smaller total uncertainty of the

system. The internal sensor has to deal with quick temperature changes,

vibration and possible mechanical shocks so it has to be quite a robust

mechanically. Unfortunately, mechanical robustness is usually inversely

proportional to good performance: stability, hysteresis, etc.

The internal sensor is used just to adjust temperature close to the

desired calibration point and keep it stable. There are many advantages

to using a separate reference sensor. It helps to minimize calibration

uncertainty but also provides reliability in measurements. In the

case of using an external reference sensor, the following uncertainty

components should be taken into account:

• Axial uniformity

Axial uniformity-related uncertainty can be minimized by aligning

the centers of the sensing elements. In many cases, the user can

reduce the axial uniformity well below specification. In case the

probe to be calibrated is short and won’t reach the measurement

zone at the bottom of the insert, the reference probe can be drawn

out to match the immersion. Of course, the stem conductance has

to be taken into account. If the reference sensor and the sensor

to be calibrated are sufficiently similar in diameter and thermal

conductivity, the user may obtain good results.

• Radial uniformity

Radial uniformity is still present when using an external reference

probe and should be taken into account as specified.

• Loading effect

Since the internal sensor cannot completely compensate the load-

related temperature shift inside the insert, the external reference

sensor is within the same calibration volume as the sensors to be

calibrated. The loading effect is usually much less significant with

an external reference sensor.

Using an external

reference sensor

enables more accurate

measurement of the

temperature of the probes

to be calibrated.



154

• Stability over time

The external reference sensor can be used to measure the actua

temperature deviation inside the insert, and it may often be smalle

than the specification. It also helps the user to see when the un

has truly stabilized. Dry blocks usually have a stability indicato

but depending on, for instance, the different loads, there may stibe some difference between the block and the insert temperature

when the indicator shows the unit has stabilized.

• External reference sensor

– The external reference sensor (PRT) is typically much more capab

of producing accurate measurements than the internal senso

However, using an external reference does not automatically mea

better results. All of the previously mentioned uncertainty facto

need to be carefully considered.

– Uncertainty related to the reference probe components includes th

probe’s calibration uncertainty, drift, hysteresis, stem conductionand the readout device’s uncertainty.

– Of course, the external reference sensor needs a unit that measure

the sensor. It can be the block or an external device.

The external reference

sensor can be used

to measure the actual

temperature deviation

inside the insert and it

also helps the user to see

when the unit has truly

stabilized.



155

CALCULATION EXAMPLES

MB155R with internal measurement @0 °C

Component Specification (°C) Standard Uncertainty (°C)Display Accuracy 0.10 0.058

Hysteresis 0.025 0.014

Axial Uniformity 0.02 0.012

Radial Uniformity 0.01 0.006

Stability 0.005 0.003

Loading Effect 0.05 0.029

Combined Uncertainty: 0.067

Expanded Uncertainty: 0.135

MB155R with external measurement @0 °CComponent Specification (°C) Standard Uncertainty (°C)

Axial Uniformity 0.02 0.012

Radial Uniformity 0.01 0.006

Stability 0.005 0.003

Loading Effect 0.005 0.003

Ref sensor measurement 0.006 0.003



Reference Sensor (Beamex RPRT-420)

Component Specification (°C) Standard Uncertainty (°C)

Short-term repeatability 0.007 0.004

Drift 0.007 0.004

Hysteresis 0.01 0.006

Calibration uncertainty 0.01 0.006



MB155R and RPRT-420

Combined uncertainty: 0.017


All specifications have a rectangular probability distribution.

That is why they are divided by the square root of three to get Standard Uncertainty.

■ Here are two examples

of total uncertaintycalculations. One is

done using the internal

temperature measurement

and the other with a

reference probe. In both

cases the MB155R is used

as the dry block.

The temperature in both

examples is 0 °C.

Due to the rectangular

probability distribution of

the specifications, they

are divided by the squareroot of three to get the

Standard Uncertainty. The

standard uncertainties

are combined as the root

sum of the squares. Finally

the combined uncertainty

has been multiplied by

two to get the expanded

uncertainty.

As can be seen in the

examples the total

expanded uncertainty

using the internal referencesensor is 135 mK

(0.135 °C). When using

an external reference

sensor the total expanded

uncertainty is 34 mK

(0.034 °C).

The various uncertainty

components used in the

examples can be found in

the specifications in the

product brochures.



157

Fieldbus is becoming more and more common in today’s

instrumentation. But what is fieldbus and how does it differ from

conventional instrumentation? Fieldbus transmitters must be

calibrated as well, but how can it be done?

Conventional transmitters can deliver only one simultaneousparameter, one way. Each transmitter needs a dedicated pair of cables,

and I/O subsystems are required to convert the analog mA signal to a

digital format for a control system.

Fieldbus transmitters are able to deliver a huge amount of

information via the quick two-way bus. Several transmitters

can be connected to the same pair of wires. Conventional I/O

systems are no longer needed because segment controllers connect the

instrument segments to the quicker, higher-level fieldbus backbone.

Being an open standard, instruments from any manufacturer can

be connected to the same fieldbus as plug-and-play.

History of fieldbus

Back in the 1940s, instrumentation utilized mainly pneumatic signals

to transfer information from transmitters. During the 1960s, the mA

signal was introduced, making things much easier. In the 1970s,

computerized control systems began to make their arrival. The first

digital, smart transmitter was introduced in the 1980s, using first

proprietary protocols. The first fieldbus was introduced in 1988, and

throughout the 1990s a number of various f ieldbuses were developed.

During the 1990s, manufacturers battled to see whose fieldbus

would be the one most commonly used. A standard was finally set

in the year 2000 when the IEC61158 standard was approved. The

Fieldbus transmitters

must also be calibrated

Fieldbus transmitters

must be calibrated as

well, but how can it be

done?



158

Foundation Fieldbus H1 and the Profibus PA, both used in proces

instrumentation, were chosen as standards.

For the most part, one can say that the Foundation Fieldbus

dominating the North American markets and the Profibus is th

market leader in Europe. Other areas are more divided. There are als

certain applications that prefer certain fieldbus installations despitthe geographical location.

Future of fieldbus

Currently, a large number of f ieldbus installations already exist an

the number is increasing at a huge rate. A large portion of new projec

is currently being carried out using f ieldbus. Critical applications an

hazardous areas have also begun to adopt f ieldbus.

The Foundation Fieldbus and Profibus have begun to clearl

dominate the fieldbus markets. Both Foundation Fieldbus and Profibu

have reached such a large market share that both buses will most likelremain also in the future. The development of new fieldbuses ha

slowed down and it is unlikely that new f ieldbus standards will appea

in the near future to challenge the position of Foundation Fieldbu

or Profibus.

Recent co-operation between Foundation Fieldbus and Profibu

suppliers will further strengthen the position of these two standards

Fieldbus benefits for industry

Obviously process plants would not start utilizing fieldbus, if

would not offer them benefits compared to alternative system

One important reason is the better return on investment. Althoug

fieldbus hardware may cost the same as conventional, or even a littl

bit more, the total installation costs for a fieldbus factory is far les

than conventional. This is caused by many reasons, such as reductio

in field wiring, lower installation labour cost, less planning/drawin

costs, and no need for conventional I/O subsystems.

Another big advantage is the on-line self-diagnostics that helps i

predictive maintenance and eventually reduces the downtime, offerin

maintenance savings. Remote configuration also helps to suppo

reduced downtime. The improved system performance is importan

criteria for some plants. There are also other advantages compared t

conventional instrumentation.

The Foundation Fieldbus

and Profibus have begun

to clearly dominate the

fieldbus market.



159

Fieldbus transmitters must also be calibrated

The main difference between a fieldbus transmitter for pressure or

temperature and conventional or HART transmitters is that the output

signal is a fully digital fieldbus signal.

The other parts of a fieldbus transmitter are mainly comparableto conventional or HART transmitters. Changing the output

signal does not change the need for periodic calibration. Although

modern fieldbus transmitters have been improved compared to older

transmitter models, it does not eliminate the need for calibration.

There are also many other reasons, such as quality systems and

regulations, that make the periodic calibrations compulsory.

Calibrating fieldbus transmitters

The word “calibration” is often misused in the fieldbus terminology

when comparing it to the meaning of the word in metrology. In fieldbusterminology, “calibration” is often used to mean the configuration of

a transmitter. In terminology pertaining to metrology, “calibration”

means that you compare the transmitter to a traceable measurement

standard and document the results.

So it is not possible to calibrate a fieldbus transmitter using only

a configurator or configuration software. Also, it is not possible to

calibrate a f ieldbus transmitter remotely.

Fieldbus transmitters are calibrated in very much the same way as

conventional transmitters – you need to place a physical input into

the transmitter and simultaneously read the transmitter output to see

that it is measuring correctly. The input is measured with a traceable

calibrator, but you also need to have a way to read the output of the

fieldbus transmitter. Reading the digital output is not always an easy

thing to do.

When fieldbus is up and running, you can have one person in the

field to provide and measure the transmitter input while another

person is in the control room reading the output. Naturally these two

people need to communicate with each other in order to perform and

document the calibration.

While your f ieldbus and process automation systems are idle, you

need to find other ways to read the transmitter’s output. In some cases

you can use a portable fieldbus communicator or a laptop computer

with dedicated software and hardware.

Although fieldbus

hardware may cost the

same as conventional,

or even a little bit more,

the total installation costs

for a fieldbus factory is

far less than conventional.



160

Fieldbus instruments are increasing in popularity and calibratio

can in many cases be cumbersome, time-consuming and may requir

an abundance of resources.

The Beamex® MC6 will help to overcome these challenges b

combining a full field communicator and an extremely accurat

multifunctional process calibrator. The Beamex® MC6 can be useas a communicator for the configuration as well as a calibrator for th

calibration of smart instruments with the supported protocols. Ther

is no need for an additional communicator. The calibration results ca

be automatically stored into the memory of the MC6 or uploaded t

calibration software.

The Beamex ® MC6

can be used as a

communicator for the

configuration as well

as a calibrator for the

calibration of smart

instruments with the

supported protocols.



163

So called “smart” instruments are ever more popular in the process

industry. The vast majority of delivered instruments today are

smart instruments. These new smart instruments bring new

challenges to the calibration and configuration processes. But what

are these smart instruments and what is the best way to configure andcalibrate them?

Beamex has recently introduced a new revolutionary tool, the

Beamex® MC6 –Advanced Field Communicator and Calibrator, that

will help to overcome these challenges.

What is a “smart” transmitter?

A process transmitter is a device that senses a physical parameter

(pressure, temperature, etc.) and generates an output signal

proportional to the measured input. The term “smart” is more of a

marketing term than a technical definition. There is no standardized

technical definition for what smart really means in practice.

Generally, in order for a transmitter to be called smart, it will utilize

a microprocessor and should also have a digital communication

protocol that can be used for reading the transmitter’s measurement

values and for configuring various settings in the transmitter. A

microprocessorbased smart transmitter has a memory that can

perform calculations, produce diagnostics, etc. Furthermore, a modern

smart transmitter typically outperforms an older type of conventional

transmitter regarding measurement accuracy and stability.

In any case, for the engineers who need to configure and calibrate

the transmitter, the digital communication protocol is the biggest

difference compared to conventional transmitters. Engineers can

Configuring and calibrating

smart instruments

A modern smart

transmitter typically

outperforms an older type

of conventional transmitter

regarding measurement

accuracy and stability.



164

no longer simply measure the output analog signal, but they need t

have the possibility to communicate with the transmitter and read th

digital signal. That brings a whole new challenge - how can the digit

output be read?

Thinking of the opposite of a smart transmitter, i.e. a non-sma

transmitter, would be a transmitter with a purely analog (or evepneumatic) output signal.

Smart transmitter protocols

There are various digital protocols that exist among transmitter

considered smart. Some are proprietary protocols of a certai

manufacturer, but these seem to be fading out in popularity and favo

is being given to protocols based on open standards because of th

interoperability that they enable.

Most of the protocols are based on open standards. The mos

common transmitter protocol today is the HART (HighwaAddressable Remote Transducer) protocol. A HART transmitte

contains both a conventional analog mA signal and a digital signa

superimposed on top of the analog signal. Since it also has the analo

signal, it is compatible with conventional installations. Recently th

HART protocol seems to be getting more boosts from the newes

WirelessHART protocol.

The fieldbuses, such as Foundation Fieldbus and Profibus, contai

only a digital output, no analog signal. Foundation Fieldbus an

Profibus are gaining a larger foothold on the process transmitte

markets.

This article will discuss “smart” transmitters, including HART

WirelessHART, Foundation Fieldbus and Profibus PA protocols.

Configuration

One important feature of a smart transmitter is that it can b

configured via the digital protocol. Configuration of a smar

transmitter refers to the setting of the transmitter parameters. Thes

parameters may include engineering unit, sensor type, etc. Th

configuration needs to be done via the communication protocol. S

in order to do the configuration, you will need to use some form o

configuration device, typically also called a communicator, to suppo

the selected protocol.

It is crucial to remember

that although a

communicator can be

used for configuration, it is

not a reference standard

and therefore cannot be

used for metrological

calibration.



165

It is crucial to remember that although a communicator can be used

for configuration, it is not a reference standard and therefore cannot

be used for metrological calibration. Configuring the parameters of a

smart transmitter with a communicator is not in itself a metrological

calibration (although it may be part of an adjustment/trim task) and

it does not assure accuracy. For a real metrological calibration, bydefinition a traceable reference standard (calibrator) is always needed.

Calibration of a smart transmitter

According to international standards, calibration is a comparison of the

device under test against a traceable reference instrument (calibrator)

and documenting the comparison. Although the calibration formally

does not include any adjustments, potential adjustments are often

included when the calibration process is performed. If the calibration

is done with a documenting calibrator, it will automatically document

the calibration results.To calibrate a conventional, analog transmitter, you can generate

or measure the transmitter input and at the same time measure the

transmitter output. In this case calibration is quite easy and straight

forward; you need a dual-function calibrator able to process transmitter

input and output at the same time, or alternatively two separate single-

function calibrators.

But how can a smart transmitter, with output being a digital protocol

signal, be calibrated? Obviously the transmitter input still needs to be

generated/measured the same way as with a conventional transmitter,

i.e. by using a calibrator. However, to see what the transmitter output

is, you will need some device or software able to read and interpret the

digital protocol. The calibration may, therefore, be a very challenging

task; several types of devices may be needed and several people to

do the job. Sometimes it is very diff icult or even impossible to find

a suitable device, especially a mobile one, which can read the digital

output.

Wired HART (as opposed to WirelessHART) is a hybrid protocol

that includes digital communication superimposed on a conventional

analog 4–20mA output signal. The 4–20mA output signal of a wired

HART transmitter is calibrated the same way as a conventional

transmitter. However, to do any configuration or tr imming, or to

read the digital output signal (if it is used), a HART communicator

is needed.

The transmitter input

needs to be generated/

measured the same way

as with a conventional

transmitter, i.e. by using a

calibrator, but in order to

see what the transmitter

output is, a device or

software able to read

and interpret the digital

protocol is needed.



166

The solution

The new Beamex® MC6 is a device combining a full fiel

communicator and an extremely accurate multifunctional proces

calibrator. With the Beamex® MC6, the smart transmitter’s input ca

be generated/ measured at the same time as reading the digital outpuThe results can be automatically stored into the memory of the MC

or uploaded to calibration software.

When it comes to configuration of the smart transmitters, th

MC6 includes a full field communicator for HART, WirelessHART

Foundation Fieldbus H1 and Profibus PA protocols. All require

electronics are built-in, including power supply and require

impedances for the protocols.

The Beamex® MC6 can be used both as a communicator fo

the configuration and as a calibrator for the calibration of sma

instruments with the supported protocols. The MC6 supports all of th

protocol commands according to the transmitter’s device descriptiofile. Any additional communicator is therefore not needed.

There are some other “smart” process calibrators on the market wit

limited support for different protocols, typically only for one protoco

(mostly HART) and offering very limited support. In practice,

separate communicator is needed in any case.

About Beamex® MC6

Beamex® MC6 is an advanced, high-accuracy field calibrato

and communicator. It offers calibration capabilities for pressure

temperature and various electrical signals. The MC6 also contain

a full fieldbus communicator for HART, Foundation Fieldbus an

Profibus PA instruments.

The usability and ease-of-use are among the main features of th

MC6. It has a large 5.7" color touch-screen with a multilingual use

interface. The robust IP65-rated dustand water-proof casing, ergonom

design and light weight make it an ideal measurement device for fiel

use in various industries, such as the pharmaceutical, energy, o

and gas, food and beverage, service as well as the petrochemical an

chemical industries.

The MC6 is one device with five different operational mode

which means that it is fast and easy to use, and you can carry les

equipment in the field. The operation modes are: meter, calibrato

With the Beamex ® MC6,

the smart transmitter’s

input can be generated/

measured at the same

time as reading the digital

output.



167

documenting calibrator, data logger and Fieldbus communicator. In

addition, the MC6 communicates with Beamex® CMX Calibration

Software, enabling fully automated and paperless calibration and

documentation.

In conclusion, the MC6 is more than a calibrator.

A modern transmitter is advertised as being smart and extremely

accurate and sometimes sales people tell you they don’t need

to be calibrated at all because they are so “smart”. So why

would you calibrate them? First of all, the output protocol of a

transmitter does not change the fundamental need for calibration.

There are numerous reasons to calibrate instruments initially and

periodically. A short summary of the main reasons include;

• Even the best instruments and sensors drift over time,

especially when used in demanding process conditions.

• Regulatory requirements, such as quality systems, safety

systems, environmental systems, standards, etc.

• Economical reasons – any measurement having direct

economical effect.

• Safety reasons- employee safety as well as customer/patient

safety.

• To achieve high and consistent product quality

and to optimize processes.

• Environmental reasons.

Why calibrate?

The MC6 also contains a

full fieldbus communicator

for HART, Foundation

Fieldbus and Profibus PA

instruments.



169

Striking a match in an environment that contains combustible

gas is nothing short of dangerous – personal injury and property

damage are likely consequences. Improperly calibrating aninstrument in this hazardous environment can be almost as dangerous.

The materials and fluids used in some processes can be hazardous in

the sense that they can ignite or explode. For example, hydrocarbons

in mines, oil refineries, and chemical plants are flammable and are

typically contained within vessels and pipes. If this were truly the case,

an external flame would not ignite the hydrocarbons. However, in

many locations, leaks, abnormal conditions, and fluid accumulation

may allow hydrocarbons to be present such that the flame could ignite

the hydrocarbons with disastrous results.

Hydrocarbons and other flammable fluids are not limited to the

petroleum and chemical industries. For example, combustible fuels,

such as natural gas, are used in all industries, including agriculture,

food, pharmaceuticals, power generation, pulp/paper, water/

wastewater, universities, retail, and in the home.

In addition, many materials and fluids used in seemingly “safe”

industries are themselves flammable. Even seemingly safe water

treatment systems use combustible materials such as chlorine in their

processes. This means that certain areas of a water treatment plant

may well be considered hazardous. Similarly, certain areas of food

plants, such as reactors that hydrogenate oils, may pose hazards as

well. Therefore, it is important for plants to examine their processes

and identify hazardous locations so that the proper instruments are

Calibration in

hazardous environments

Many materials and fluids

used in seemingly “safe”industries are themselves

flammable.



170

selected, installed, and maintained in accordance with practices tha

are appropriate for the hazard.

Equipment requirements in hazardous locations

Protection requirements for hazardous locations vary according to thtype of material present, frequency of the hazard, and the protectio

concept applied.

The intensity with which various vapors can combust is generall

different. Groupings (IEC 60079-10) in order of decreasing ignitio

energy (with an example of a gas in the group) are:

Group IIC Acetylene

Group IIB+H2 Hydrogen

Group IIB Ethylene

Group IIA Propane

The hazardous area classifications (IEC 60079-10) in order o

decreasing frequency are:

Zone 0 Flammable material present continuously

Zone 1 Flammable material present intermittently

Zone 2 Flammable material present abnormally

Intrinsic Safety (IS) is the most common protection concept applie

to calibrators that are used in hazardous locations. In general, the I

concept is to design the calibrator such that it limits the amount o

energy available such that it cannot ignite a combustible gas mixtur

Adding the applicability of IS designs to various hazards in th

previous table yields:

Zone 0 ia Flammable material present continuously

Zone 1 ia, ib Flammable material present intermittently

Zone 2 ia, ib Flammable material present abnormally

In addition, a hot surface temperature on a device can cause ignition

Temperature classes limit the maximum surface temperature betwee

450˚C (T1) and 85˚C (T6).

Intrinsic Safety (IS)

is the most common

protection concept

applied to calibrators

used in hazardous

locations.



171

Beamex calibrators for hazardous locations are designed and certif ied

for Ex ia IIC T4 hazards per the ATEX Directive and are applicable to

all vapor hazards where a temperature class of 135˚C in a 50˚C ambient

is acceptable. As such, they can be used for the overwhelming majority

of applications where a vapor hazard is present.

Calibration solutions for hazardous locations

Instruments designed to measure flow, level, pressure, temperature,

and other variables designed in hazardous locations are generally used

to monitor and control the process. In some applications, it is practical

to remove these instruments and calibrate them on the workshop with

a calibration test bench. This is usually not the case, which means that

many instruments are calibrated in the field. Fortunately, there are

calibrators that are specifically designed to operate safely in rugged

environments and hazardous locations.

The Beamex multifunction IS-calibrators are portable andintrinsically safe and have modules that can accommodate wide ranges

and many types of pressure, RTD, thermocouple, voltage, current,

pulse, and frequency measurements.

The Beamex modular calibration system is a test bench and

calibration system for workshops and laboratories that incorporates

the functionality of the MC5 multifunction calibrator and can

measure/generate additional parameters such as precision pressures.

The ergonomic design and modular construction allow the user to

select the necessary functions in a cost-effective manner.

The Beamex® CMX software integrates calibration management by

allowing efficient planning and scheduling of calibration work. It not

only alerts you when to calibrate, but also automatically takes data,

creates documentation, adheres to GMP regulations (21 CFR 11), and

tracks calibration history. This software generally makes calibration

work faster and easier and is designed to integrate into management

systems such as SAP and Maximo.

The Beamex ® CMX

software integrates


by allowing efficient

planning and scheduling

of calibration work.



172

A few points to remember

• Improper actions in hazardous locations can result in propert

damage and bodily injury.

• Hazardous locations can exist in virtually all industries, stores, anin the home.

• Instruments should be specified, installed, operated, and maintaine

in accordance with requirements for the hazardous location.

• Portable Beamex calibrators for hazardous locations are designed t

be used in virtually all vapor hazards.Hazardous locations

can exist in virtually all

industries, stores,

and in the home.



173



175

Fieldbus transmitters must also be calibrated just like conventional

instruments. There are also industrial environments where the

calibration of fieldbus instruments should not only be made

accurately and efficiently, but also safely. When safety becomes a top

priority issue in calibration, intrinsically safe fieldbus calibrators enterinto the picture.

By definition, intrinsic safety (IS) is a protection technique for

safely operating electronic equipment in explosive environments.

The concept has been developed for safely operating process control

instrumentation in hazardous areas. The idea behind intrinsic safety

is to make sure that the available electrical and thermal energy in a

system is always low enough that ignition of the hazardous atmosphere

cannot occur. A hazardous atmosphere is an area that contains

elements that may cause an explosion: source of ignition, a flammable

substance and oxygen.

An intrinsically safe calibrator is therefore designed to be incapable

of causing ignition in the surrounding environment with flammable

materials, such as gases, mists, vapors or combustible dust. Intrinsically

safe calibrators are also often referred to being “Ex calibrators”,

“calibrators for Ex Areas”, or “IS calibrators”. An Ex Area also refers

to an explosive environment and an Ex calibrator is a device designed

for use in the type of environment in question.

Where is intrinsically safe calibration required?

Many industries require intrinsically safe calibration equipment.

Intrinsically safe calibrators are designed for potentially explosive

environments, such as oil refineries, rigs and processing plants, gas

The safest way to calibrate

fieldbus instruments

Hazardous area

classifications in IEC/

European countries are:

Zone 0: an explosive gas

& air mixture is continuously

present or present for a long

time.

Zone 1: an explosive gas &

air mixture is likely to occur

in normal operation.

Zone 2: an explosive gas

& air mixture is not likely to

occur in normal operation,and if it occurs it will exist

only for a short time.



176

pipelines and distribution centres, petrochemical and chemical plant

as well as pharmaceutical plants. Basically, any potentially explosiv

industrial environment can benefit from using intrinsically saf

calibrators.

What are the benefits of using intrinsically safe calibrators?

There are clear benefits in using intrinsically safe calibratio

equipment. First of all, it is the safest possible technique. Secondly

the calibrators provide performance and functionality.

Safest possible technique

Intrinsically safe calibrators are safe for employees, as they

can be safely used in environments where the risk of an

explosion exists. In addition, intrinsically safe calibrators

are the only technique permitted for Zone 0 environments

(explosive gas and air mixture is continuously present orpresent for a long time).

Performance and functionality

Multifunctional intrinsically safe calibrators provide

the functionality and performance of regular industrial

calibration devices, but in a safe way. They can be used

for calibration of pressure, temperature and electrical

signals. A documenting intrinsically safe calibrator, such

as the Beamex® MC5- IS, provides additional efficiency

improvements with its seamless communication with

calibration software. This eliminates the need of manualrecording of calibration data and improves the quality and

productivity of the entire calibration process.

Are intrinsically safe calibrators technically different from regula

industrial calibrators?

Intrinsically safe calibrators are different from other industria

calibrators in both design and technical features. In view of safety

there are also some guidelines and constraints for how to use them i

hazardous areas. Every intrinsically safe calibrator is delivered with

product safety note, which should be read carefully before using th

device. The product safety note lists all the “do’s and don’ts” for saf

calibration.

Basically, any potentially

explosive industrial

environment can benefit

from using intrinsically

safe calibrators.



177

The differences in design and technical features were made with one

purpose in mind—to ensure that the device is safe to use and is unable

to cause an ignition. The surface of the device is made of conductive

material. The battery of an intrinsically safe calibrator is usually slower

to charge and it discharges quicker. Many times intrinsically safe

equipment operate only with dry batteries, but the Beamex intrinsicallysafe calibrators operate with chargeable batteries. When charging the

battery, it must be done in a non-Ex area. External pressure modules

can be used with IS-calibrators, but they must also be intrinsically

safe. There are also usually small differences with electrical ranges

compared to regular industrial calibrators (e.g. maximum is lower).

Making a calibrator safe and unable to cause ignition – typical

technical differences:

• Surface made of conductive material

• Constraints in using the device (listed in Product Safety Note)• Small differences with electrical ranges (e.g. maximum is lower)

• Battery slower to charge, quicker to discharge

• Battery must be charged in a non-Ex area

• When using external pressure modules, they must be IS-versions

What are ATEX and IECEx?

ATEX (“ATmosphères EXplosibles”, explosive atmospheres in French)

is a standard set in the European Union for explosion protection in the

industry. ATEX 95 equipment directive 94/9/EC concerns equipment

intended for use in potentially explosive areas. Companies in the

EU where the risk of explosion is evident must also use the ATEX

guidelines for protecting the employees. In addition, the ATEX rules

are obligatory for electronic and electrical equipment that will be used

in potentially explosive atmospheres sold in the EU as of July 1, 2003.

IEC (International Electrotechnical Commission) is a nonprofit

international standards organization that prepares and publishes

international standards for electrical technologies. The IEC TC/31

technical committee deals with the standards related to equipment for

explosive atmospheres. IECEx is an international scheme for certifying

procedures for equipment designed for use in explosive atmospheres.

The objective of the IECEx Scheme is to facilitate international trade

in equipment and services for use in explosive atmospheres, while

maintaining the required level of safety.

The differences in design

and technical features

were made with one

purpose in mind – to

ensure that the device is

safe to use and is unable

to cause an ignition.



178

As Beamex® MC5-IS Intrinsically Safe Multifunction Calibrator

certified according to ATEX and the IECEx Scheme, it ensures th

calibrator is fit for its intended purpose and that suff icient informatio

is supplied with it to ensure that it can be used safely.

Is service different for intrinsically safe calibrators?

There are certain aspects that need special attention when doin

service or repair on an intrinsically safe calibrator. The most importan

thing to remember is that an intrinsically safe calibrator must maintai

its intrinsic safety after the service or repair. The best way to do th

is to send it to the manufacturer or to an authorized service compan

for repair. Recalibration can be done by calibration laboratories (sti

preferably with ISO/IEC 17025 accreditation).

Safe fieldbus calibration with the Beamex®

MC5-IS IntrinsicallySafe Multifunction Calibrator

The Beamex® MC5-IS Intrinsically Safe Multifunction Calibrato

is a high accuracy, all-in-one calibrator for extreme environment

Being an all-in-one calibrator, the MC5-IS replaces many individu

measurement devices and calibrators. The MC5-IS is also ATEX

and IECEx certified. The MC5-IS has calibration capabilitie

for pressure, temperature, electrical and frequency signals. It

a documenting calibrator, which means that it communicate

seamlessly with calibration software. Using documenting calibrato

with calibration software can remarkably improve the efficiency an

quality of the entire calibration process. The MC5-IS also has HAR

communication. The MC5-IS also has HART communication. Th

MC5-IS can also be used for calibrating Foundation Fieldbus H1 o

Profibus PA transmitters.

The most important thing

to remember is that an

intrinsically safe calibrator

must maintain its intrinsic

safety after the service or

repair.



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This glossary is a quick reference to the meaning of common

terms. It is a supplement to the VIM, GUM, NCSL Glossary,

and the information in the other references listed at the end.In technical, scientific and engineering work (such as metrology)

it is important to correctly use words that have a technical meaning.

Definitions of these words are in relevant national, international

and industry standards; journals; and other publications, as well as

publications of relevant technical and professional organizations.

Those documents give the intended meaning of the word, so everyone

in the business knows what it is. In technical work, only the technical

definitions should be used.

Many of these def initions are adapted from the references. In some

cases several may be merged to better clarify the meaning or adapt

the wording to common metrology usage. The technical definitions

may be different from the definitions published in common grammar

dictionaries. However, the purpose of common dictionaries is to record

the ways that people actually use words, not to standardize the way

the words should be used. If a word is defined in a technical standard, its

definition from a common grammar dictionary should never be used in work

where the technical standard can apply.

Calibration terminology

A to Z1

______________

1. Bucher, Jay L. 2004. The Metrology Handbook . Milwaukee: ASQ Quality Press.



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Terms that are not in this glossary may be found in one of thes

primary references:

1. ISO. 1993. International vocabulary of basic and general terms i

metrology (called the VIM); BIPM, IEC, IFCC, ISO, IUPAC

IUPAP, and OIML. Geneva: ISO.2. ANSI/NCSL. 1997. ANSI/NCSL Z540-2-1997, U. S. Guide to th

expression of uncertainty in measurement (called the GUM). Boulde

CO: NCSL International.

3. NCSL. 1999. NCSL Glossary of metrology-related terms. 2nd ed

Boulder, CO: NCSL International.

Some terms may be listed in this glossary in order to expand o

the definition, but should be considered an addition to the reference

listed above, not a replacement of them. (It is assumed that a calibratio

or metrology activity owns copies of these as part of its basic referenc

material.)

Glossary

Accreditation (of a laboratory) – Formal recognition by an accreditatio

body that a calibration or testing laboratory is able to competentl

perform the calibrations or tests listed in the accreditatio

scope document. Accreditation includes evaluation of both th

quality management system and the competence to perform th

measurements listed in the scope.

Accreditation body – An organization that conducts laborator

accreditation evaluations in conformance to ISO Guide 58.

Accreditation certificate – Document issued by an accreditatio

body to a laboratory that has met the conditions and criteria fo

accreditation. The certificate, with the documented measuremen

parameters and their best uncertainties, serves as proof of accredite

status for the time period listed. An accreditation certificat

without the documented parameters is incomplete.

Accreditation criteria – Set of requirements used by an accreditin

body that a laboratory must meet in order to be accredited.

Accuracy (of a measurement) – Accuracy is a qualitative indication o

how closely the result of a measurement agrees with the true valu

of the parameter being measured. (VIM, 3.5) Because the tru

value is always unknown, accuracy of a measurement is alway



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an estimate. An accuracy statement by itself has no meaning

other than as an indicator of quality. It has quantitative value

only when accompanied by information about the uncertainty

of the measuring system. Contrast with: accuracy (of a measuring

instrument)

Accuracy (of a measuring instrument) – Accuracy is a qualitativeindication of the ability of a measuring instrument to give

responses close to the true value of the parameter being measured.

(VIM, 5.18) Accuracy is a design specification and may be verified

during calibration. Contrast with: accuracy (of a measurement)

Application – Software installed on a defined platform/hardware

providing specific functionality

Assessment – Examination typically performed on-site of a testing or

calibration laboratory to evaluate its conformance to conditions

and criteria for accreditation.

Bespoke/Customized computerised system – A computerised system

individually designed to suit a specific business process Best measurement capability – For an accredited laboratory, the best

measurement capability for a particular quantity is “the smallest

uncertainty of measurement a laboratory can achieve within its

scope of accreditation when performing more or less routine

calibrations of nearly ideal measurement standards intended to

define, realize, conserve, or reproduce a unit of that quantity or

one or more of its values; or when performing more-or-less routine

calibrations of nearly ideal measuring instruments designed for the

measurement of that quantity.” (EA-4/02) The best measurement

capability is based on evaluations of actual measurements

using generally accepted methods of evaluating measurement

uncertainty.

Bias – Bias is the known systematic error of a measuring instrument.

(VIM, 5.25) The value and direction of the bias is determined by

calibration and/or gage R&R studies. Adding a correction, which

is always the negative of the bias, compensates for the bias. See also:

correction, systematic error

Calibration – (1). (See VIM 6.11 and NCSL pages 4–5 for primary

and secondary definitions.) Calibration is a term that has many

different – but similar – definitions. It is the process of verifying

the capability and performance of an item of measuring and test

equipment by comparison to traceable measurement standards.

Calibration is performed with the item being calibrated in



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its normal operating configuration – as the normal operato

would use it. The calibration process uses traceable externa

stimuli, measurement standards, or artifacts as needed to verif

the performance. Calibration provides assurance that th

instrument is capable of making measurements to its performanc

specif ication when it is correctly used. The result of a calibration a determination of the performance quality of the instrument wit

respect to the desired specifications. This may be in the form o

a pass/fail decision, determining or assigning one or more value

or the determination of one or more corrections. The calibratio

process consists of comparing an IM&TE unit with specifie

tolerances, but of unverified accuracy, to a measurement system

or device of specified capability and known uncertainty in orde

to detect, report, or minimize by adjustment any deviations from

the tolerance limits or any other variation in the accuracy of th

instrument being compared. Calibration is performed accordin

to a specified documented calibration procedure, under a set ospecified and controlled measurement conditions, and with

specified and controlled measurement system.

Notes:

• A requirement for calibration does not imply that the item

being calibrated can or should be adjusted.

• The calibration process may include, if necessary, calculatio

of correction factors or adjustment of the instrument bein

compared to reduce the magnitude of the inaccuracy.

• In some cases, minor repair such as replacement of batterie

fuses, or lamps, or minor adjustment such as zero and span

may be included as part of the calibration.

• Calibration does not include any maintenance or repair action

except as just noted. See also: performance test, calibratio

procedure Contrast with: calibration (2) and repair

Calibration – 2 A) Many manufacturers incorrectly use the term

calibration to name the process of alignment or adjustment o

an item that is either newly manufactured or is known to be ou

of tolerance, or is otherwise in an indeterminate state. Man

calibration procedures in manufacturers’ manuals are actuall

factory alignment procedures that only need to be performed if

UUC is in an indeterminate state because it is being manufactured



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is known to be out of tolerance, or after it is repaired. When used

this way, calibration means the same as alignment or adjustment,

which are repair activities and excluded from the metrological

definition of calibration.

(B) In many cases, IM&TE instruction manuals may use

calibration to describe tasks normally performed by the operatorof a measurement system. Examples include performing a self-

test as part of normal operation or performing a self-calibration

(normalizing) a measurement system before use. When calibration

is used to refer to tasks like this, the intent is that they are part

of the normal work done by a trained user of the system. These

and similar tasks are excluded from the metrological definition of

calibration. Contrast with: calibration (1) See also: normalization,

self-calibration, standardization

Calibration activity or provider – A laboratory or facility – including

personnel – that perform calibrations in an established location or

at customer location(s). It may be external or internal, includingsubsidiary operations of a larger entity. It may be called a calibration

laboratory, shop, or department; a metrology laboratory or

department; or an industry-specif ic name; or any combination or

variation of these.

Calibration certificate – (1) A calibration certificate is generally a

document that states that a specific item was calibrated by an

organization. The certificate identifies the item calibrated, the

organization presenting the certificate, and the effective date. A

calibration certificate should provide other information to allow

the user to judge the adequacy and quality of the calibration. (2)

In a laboratory database program, a certificate often refers to the

permanent record of the final result of a calibration. A laboratory

database certificate is a record that cannot be changed; if it is

amended later a new certificate is created. See also: calibration

report

Calibration procedure – A calibration procedure is a controlled

document that provides a validated method for evaluating and

verifying the essential performance characteristics, specifications,

or tolerances for a model of measuring or testing equipment.

A calibration procedure documents one method of verifying

the actual performance of the item being calibrated against its

performance specifications. It provides a list of recommended

calibration standards to use for the calibration; a means to record



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quantitative performance data both before and after adjustment

and information suff icient to determine if the unit being calibrate

is operating within the necessary performance specifications. A

calibration procedure always starts with the assumption that th

unit under test is in good working order and only needs to hav

its performance verified. Note: A calibration procedure does noinclude any maintenance or repair actions.

Calibration program – A calibration program is a process of th

quality management system that includes management of th

use and control of calibrated inspection, and test and measurin

equipment (IM&TE), and the process of calibrating IM&TE use

to determine conformance to requirements or used in supportin

activities. A calibration program may also be called a measuremen

management system (ISO 10012:2003).

Calibration report – A calibration report is a document that provide

details of the calibration of an item. In addition to the basic item

of a calibration certif icate, a calibration report includes details othe methods and standards used, the parameters checked, and th

actual measurement results and uncertainty. See also: calibratio

certificate

Calibration seal – A calibration seal is a device, placard, or label tha

when removed or tampered with, and by virtue of its design an

material, clearly indicates tampering. The purpose of a calibratio

seal is to ensure the integrity of the calibration. A calibration sea

is usually imprinted with a legend similar to “Calibration Voi

if Broken or Removed” or “Calibration Seal – Do Not Break o

Remove.” A calibration seal provides a means of deterring the use

from tampering with any adjustment point that can affect th

calibration of an instrument and detecting an attempt to acces

controls that can affect the calibration of an instrument. Note:

calibration seal may also be referred to as a tamper seal.

Calibration standard – (See VIM, 6.1 through 6.9, and 6.13, 6.14

and NCSL pages 36–38.) A calibration standard is an IM&T

item, artifact, standard reference material, or measuremen

transfer standard that is designated as being used only to perform

calibrations of other IM&TE items. As calibration standard

are used to calibrate other IM&TE items, they are more closel

controlled and characterized than the workload items they ar

used for. Calibration standards generally have lower uncertaint

and better resolution than general-purpose items. Designation as



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calibration standard is based on the use of the specific instrument,

however, not on any other consideration. For example, in a group

of identical instruments, one might be designated as a calibration

standard while the others are all general purpose IM&TE items.

Calibration standards are often called measurement standards. See

also: standard (measurement)Combined standard uncertainty – The standard uncertainty of the

result of a measurement, when that result is obtained from the

values of a number of other quantities. It is equal to the positive

square root of a sum of terms. The terms are the variances or

covariances of these other quantities, weighted according to how

the measurement result varies with changes in those quantities.

(GUM, 2.3.4) See also: expanded uncertainty

Commercial of the shelf software – Software commercially available,

whose fitness for use is demonstrated by a broad spectrum of users.

Competence – For a laboratory, the demonstrated ability to perform

the tests or calibrations within the accreditation scope and to meetother criteria established by the accreditation body. For a person,

the demonstrated ability to apply knowledge and skills. Note: The

word qualification is sometimes used in the personal sense, since

it is a synonym and has more accepted usage in the United States.

Confidence interval – A range of values that is expected to contain the

true value of the parameter being evaluated with a specif ied level

of confidence. The confidence interval is calculated from sample

statistics. Confidence intervals can be calculated for points, lines,

slopes, standard deviations, and so on. For an infinite (or very large

compared to the sample) population, the confidence interval is:

where

CI is the confidence interval,

n is the number of items in the sample,

p is the proportion of items of a given type in the population,

s is the sample standard deviation,

x is the sample mean, and

t is the Student’s T value for α ⁄2 and (n – 1) (α is the level of

significance).

s p (1 – p)

CI = x̄ ± t = ––– or CI = p ± –––––––––

n n



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Correction (of error) – A correction is the value that is added to th

raw result of a measurement to compensate for known or estimate

systematic error or bias. (VIM, 3.15) Any residual amount is treate

as random error. The correction value is equal to the negative o

the bias. An example is the value calculated to compensate fo

the calibration difference of a reference thermometer or for thcalibrated offset voltage of a thermocouple reference junction. S

also: bias, error, random error, systematic error

Corrective action – Corrective action is something done to correct

nonconformance when it arises, including actions taken to preven

reoccurrence of the nonconformance. Compare with: preventiv

action

Coverage factor – A numerical factor used as a multiplier of th

combined standard uncertainty in order to obtain an expande

uncertainty. (GUM, 2.3.6) The coverage factor is identified b

the symbol k . It is usually given the value 2, which approximatel

corresponds to a probability of 95 percent for degrees of freedom> 10’.

Deficiency – Nonfulfillment of conditions and/or criteria fo

accreditation, sometimes referred to as a nonconformance.

Departure value – A term used by a few calibration laboratories to refe

to bias, error or systematic error. The exact meaning can usually b

determined from examination of the calibration certificate.

Equivalence – (A) Acceptance of the competence of other nationa

metrology institutes (NMI), accreditation bodies, and/or accredite

organizations in other countries as being essentially equal to th

NMI, accreditation body, and/or accredited organizations withi

the host country.

(B) A formal, documented determination that a specific instrumen

or type of instrument is suitable for use in place of the one originall

listed, for a particular application.

Error (of measurement) – (See VIM, 3.10, 3.12–3.14; and NCSL page

11–13.) In metrology, error (or measurement error) is an estimat

of the difference between the measured value and the probabl

true value of the object of the measurement. The error ca

never be known exactly; it is always an estimate. Error may b

systematic and/or random. Systematic error (also known as bia

may be corrected. See also: bias, correction (of error), random erro

systematic error

Gage R&R – Gage repeatability and reproducibility study, whic



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(typically) employs numerous instruments, personnel, and

measurements over a period of time to capture quantitative

observations. The data captured are analyzed statistically to obtain

best measurement capability, which is expressed as an uncertainty

with a coverage factor of k = 2 to approximate 95 percent. The

number of instruments, personnel, measurements, and length oftime are established to be statistically valid consistent with the size

and level of activity of the organization.

GUM – An acronym commonly used to identify the ISO Guide to the

Expression of Uncertainty in Measurement. In the United States, the

equivalent document is ANSI/NCSL Z540-2-1997, U. S. Guide to

the Expression of Uncertainty in Measurement.

IM&TE – The acronym IM&TE refers to inspection, measuring,

and test equipment. This term includes all items that fall under

a calibration or measurement management program. IM&TE

items are typically used in applications where the measurement

results are used to determine conformance to technical or qualityrequirements before, during, or after a process. Some organizations

do not include instruments used solely to check for the presence

or absence of a condition (such as voltage, pressure, and so on)

where a tolerance is not specif ied and the indication is not critical

to safety. Note: Organizations may refer to IM&TE items as MTE

(measuring and testing equipment), TMDE (test, measuring,

and diagnostic equipment), GPETE (general purpose electronic

test equipment), PME (precision measuring equipment), PMET

(precision measuring equipment and tooling), or SPETE (special

purpose electronic test equipment).

Inte rlaboratory comparison – Organization, performance, and

evaluation of tests or calibrations on the same or similar items

or materials by two or more laboratories in accordance with

predetermined conditions.

Internal audit – A systematic and documented process for obtaining

audit evidence and evaluating it objectively to verify that a

laboratory’s operations comply with the requirements of its quality

system. An internal audit is done by or on behalf of the laboratory

itself, so it is a first-party audit.

International Organization for Standardization (ISO) – An international

nongovernmental organization chartered by the United Nations

in 1947, with headquarters in Geneva, Switzerland. The mission

of ISO is “to promote the development of standardization and



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related activities in the world with a view to facilitating th

international exchange of goods and services, and to developin

cooperation in the spheres of intellectual, scientific, technologic

and economic activity.” The scope of ISO’s work covers all f ields o

business, industry and commerce except electrical and electroni

engineering. The members of ISO are the designated nationastandards bodies of each country. (The United States is represente

by ANSI.) See also: ISO

International System of Units (SI) – A defined and coherent system o

units adopted and used by international treaties. (The acronym S

is from the French Systéme International.) SI is international system

of measurement for all physical quantities. (Mass, length, amoun

of substance, time, electric current, thermodynamic temperatur

and luminous intensity.) SI units are defined and maintained b

the International Bureau of Weights and Measures (BIPM) in Pari

France. The SI system is popularly known as the metric system.

ISO – Iso is a Greek word root meaning equal. The InternationaOrganization for Standardization chose the word as the sho

form of the name, so it will be a constant in all languages. In th

context, ISO is not an acronym. (If the acronym was based on th

full name were used, it would be different in each language.) Th

name also symbolizes the mission of the organization – to equaliz

standards worldwide.

IT Infrastructure – The hardware and software such as networkin

software and operation systems, which makes it possible for th

application to function.

Level of confidence – Defines an interval about the measurement resu

that encompasses a large fraction p of the probability distributio

characterized by that result and its combined standard uncertainty

and p is the coverage probability or level of confidence of th

interval. Effectively, the coverage level expressed as a percent.

Life cycle – All phases in the life of the system from initial requiremen

until retirement including design, specification, programming

testing, installation, operation, and maintenance.

Management review – The planned, formal, periodic, and schedule

examination of the status and adequacy of the quality managemen

system in relation to its quality policy and objectives by th

organization’s top management.

Measurement – A set of operations performed for the purpose o

determining the value of a quantity. (VIM, 2.1)



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Measurement system – A measurement system is the set of equipment,

conditions, people, methods, and other quantifiable factors that

combine to determine the success of a measurement process.

The measurement system includes at least the test and measuring

instruments and devices, associated materials and accessories, the

personnel, the procedures used, and the physical environment.Metrology – Metrology is the science and practice of measurement

(VIM, 2.2).

Mobile operations – Operations that are independent of an established

calibration laboratory facility. Mobile operations may include work

from an off ice space, home, vehicle, or the use of a virtual off ice.

Natural (physical) constant – A natural constant is a fundamental

value that is accepted by the scientific community as valid. Natural

constants are used in the basic theoretical descriptions of the

universe. Examples of natural physical constants important in

metrology are the speed of light in a vacuum (c), the triple point of

water (273.16 K), the quantum charge ratio (h/e), the gravitationalconstant (G), the ratio of a circle’s circumference to its diameter

(p), and the base of natural logarithms (e).

NCSL international – Formerly known as the National Conference

of Standards Laboratories (NCSL). NCSL was formed in

1961 to “promote cooperative efforts for solving the common

problems faced by measurement laboratories. NCSL has member

organizations from academic, scientific, industrial, commercial

and government facilities around the world. NCSL is a nonprofit

organization, whose membership is open to any organization with

an interest in the science of measurement and its application in

research, development, education, or commerce. NCSL promotes

technical and managerial excellence in the field of metrology,

measurement standards, instrument calibration, and test and

measurement.”

Normalization, Normalize – See: self-calibration

Offset – Offset is the difference between a nominal value (for an

artifact) or a target value (for a process) and the actual measured

value. For example, if the thermocouple alloy leads of a reference

junction probe are formed into a measurement junction and placed

in an ice point cell, and the reference junction itself is also in the

ice point, then the theoretical thermoelectric emf measured at the

copper wires should be zero. Any value other than zero is an offset

created by inhomogeneity of the thermocouple wires combined



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with other uncertainties. Compare with: bias, error

On-site operations – Operations that are based in or directly supporte

by an established calibration laboratory facility, but actuall

perform the calibration actions at customer locations. This include

climate-controlled mobile laboratories.

Performance Test – A performance test (or performance verification) the activity of verifying the performance of an item of measurin

and test equipment to provide assurance that the instrument

capable of making correct measurements when it is properly used

A performance test is done with the item in its normal operatin

configuration. A performance test is the same as a calibration (1

See also: calibration (1)

Policy – A policy defines and sets out the basic objectives, goal

vision, or general management position on a specific topic. A

policy describes what management intends to have done regardin

a given portion of business activity. Policy statements relevant t

the quality management system are generally stated in the qualitmanual. Policies can also be in the organization’s policy/procedur

manual. See also: procedure

Precision – Precision is a property of a measuring system or instrumen

Precision is a measure of the repeatability of a measuring system – how

much agreement there is within a group of repeated measuremen

of the same quantity under the same conditions. (NCSL, page 26

Precision is not the same as accuracy. (VIM, 3.5)

Preventive action – Preventive action is something done to prevent th

possible future occurrence of a nonconformance, even though suc

an event has not yet happened. Preventive action helps improve th

system. Contrast with: corrective action

Procedure – A procedure describes a specific process for implementin

all or a portion of a policy. There may be more than one procedur

for a given policy. A procedure has more detail than a policy bu

less detail than a work instruction. The level of detail neede

should correlate with the level of education and training of th

people with the usual qualif ications to do the work and the amoun

of judgment normally allowed to them by management. Som

policies may be implemented by fairly detailed procedures, whil

others may only have a few general guidelines. Calibration: se

calibration procedure. See also: policy

Process owner – The person responsible for the business process.



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Proficiency testing – Determination of laboratory testing performance

by means of interlaboratory comparisons.

Quality manual – The quality manual is the document that describes

the quality management policy of an organization with respect to a

specified conformance standard. The quality manual briefly defines

the general policies as they apply to the specified conformancestandard and affirms the commitment of the organization’s top

management to the policy. In addition to its regular use by the

organization, auditors use the quality manual when they audit

the quality management system. The quality manual is generally

provided to customers on request. Therefore, it does not usually

contain any detailed policies and never contains any procedures,

work instructions, or proprietary information.

Random error – Random error is the result of a single measurement of

a value, minus the mean of a large number of measurements of the

same value. (VIM, 3.13) Random error causes scatter in the results

of a sequence of readings and, therefore, is a measure of dispersion.Random error is usually evaluated by Type A methods, but Type

B methods are also used in some situations. Note: Contrary to

popular belief, the GUM specifically does not replace random

error with either Type A or Type B methods of evaluation. See also:

error Compare with: systematic error

Repair – Repair is the process of returning an unserviceable or

nonconforming item to serviceable condition. The instrument is

opened, or has covers removed, or is removed from its case and

may be disassembled to some degree. Repair includes adjustment

or alignment of the item as well as component-level repair. (Some

minor adjustment such as zero and span may be included as part of

the calibration.) The need for repair may be indicated by the results

of a calibration. For calibratable items, repair is always followed by

calibration of the item. Passing the calibration test indicates success

of the repair. Contrast with: calibration (1), repair (minor)

Repair (minor) – Minor repair is the process of quickly and economically

returning an unserviceable item to serviceable condition by doing

simple work using parts that are in stock in the calibration lab.

Examples include replacement of batteries, fuses, or lamps; or

minor cleaning of switch contacts; or repairing a broken wire; or

replacing one or two in-stock components. The need for repair may

be indicated by the results of a calibration. For calibratable items,

minor repair is always followed by calibration of the item. Passing



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the calibration test indicates success of the repair. Minor repairs a

defined as repairs that take no longer than a short time as define

by laboratory management, and where no parts have to be ordere

from external suppliers, and where substantial disassembly of th

instrument is not required. Contrast with: calibration (1), repair

Reported value – One or more numerical results of a calibratioprocess, with the associated measurement uncertainty, as recorde

on a calibration report or certificate. The specific type and forma

vary according to the type of measurement being made. In genera

most reported values will be in one of these formats:

• Measurement result and uncertainty. The reported value

usually the mean of a number of repeat measurements. Th

uncertainty is usually expanded uncertainty as def ined in th

GUM.

• Deviation from the nominal (or reference) value an

uncertainty. The reported value is the difference betwee

the nominal value and the mean of a number of repeameasurements. The uncertainty of the deviation is usuall

expanded uncertainty as defined in the GUM.

• Estimated systematic error and uncertainty. The value may b

reported this way when it is known that the instrument is pa

of a measuring system and the systematic error will be use

to calculate a correction that will apply to the measuremen

system results.

Round robin – See: Interlaboratory Comparison

Scope of accreditation – For an accredited calibration or testin

laboratory, the scope is a documented list of calibration or testin

fields, parameters, specific measurements, or calibrations an

their best measurement, uncertainty. The scope document is a

attachment to the certificate of accreditation and the certificate

incomplete without it. Only the calibration or testing areas tha

the laboratory is accredited for are listed in the scope documen

and only the listed areas may be offered as accredited calibration

or tests. The accreditation body usually defines the format an

other details.

Self-calibration – Self-calibration is a process performed by a user fo

the purpose of making an IM&TE instrument or system read

for use. The process may be required at intervals such as ever

power-on sequence; or once per shift, day, or week of continuou

operation; or if the ambient temperature changes by a specifie



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amount. Once initiated, the process may be performed totally by the

instrument or may require user intervention and/or use of external

calibrated artifacts. The usual purpose is accuracy enhancement

by characterization of errors inherent in the measurement system

before the item to be measured is connected. Self-calibration is

not equivalent to periodic calibration (performance verification)because it is not performed using a calibration procedure and does

not meet the metrological requirements for calibration. Also, if

an instrument requires self-calibration before use, then that will

also be accomplished at the start of a calibration procedure. Self-

calibration may also be called normalization or standardization.

Compare with: calibration (2.B) Contrast with: calibration (1)

Specification – In metrology, a specification is a documented statement

of the expected performance capabilities of a large group of

substantially identical measuring instruments, given in terms of

the relevant parameters and including the accuracy or uncertainty.

Customers use specifications to determine the suitability of aproduct for their own applications. A product that performs

outside the specification limits when tested (calibrated) is rejected

for later adjustment, repair, or scrapping.

Standard (document) – A standard (industry, national, government, or

international standard; a norme ) is a document that describes the

processes and methods that must be performed in order to achieve

a specific technical or management objective, or the methods for

evaluation of any of these. An example is ANSI/NCSL Z540-1-

1994, a national standard that describes the requirements for the

quality management system of a calibration organization and the

requirements for calibration and management of the measurement

standards used by the organization.

Standard (measurement) – A standard (measurement standard,

laboratory standard, calibration standard, reference standard; an

étalon) is a system, instrument, artifact, device, or material that

is used as a defined basis for making quantitative measurements.

The value and uncertainty of the standard define a limit to the

measurements that can be made: a laboratory can never have better

precision or accuracy than its standards. Measurement standards

are generally used in calibration laboratories. Items with similar

uses in a production shop are generally regarded as working-level

instruments by the calibration program.

Primary standard. Accepted as having the highest metrological



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qualities and whose value is accepted without reference to othe

standards of the same quantity. Examples: triple point of water ce

and caesium beam frequency standard.

Transfer standard. A device used to transfer the value of

measurement quantity (including the associated uncertainty) from

a higher level to a lower level standard.Secondary standard. The highest accuracy level standards in

particular laboratory generally used only to calibrate workin

standards. Also called a reference standard.

Working standard. A standard that is used for routine calibratio

of IM&TE. The highest level standards, found in national an

international metrology laboratories, are the realizations o

representations of SI units. See also: calibration standard

Standard operating procedure (SOP) – A term used by some organization

to identify policies, procedures, or work instructions.

Standard reference material – A standard reference material (SRM) a

defined by NIST “is a material or artifact that has had one or morof its property values certified by a technically valid procedure

and is accompanied by, or traceable to, a certificate or othe

documentation which is issued by NIST… Standard referenc

materials are…manufactured according to strict specification

and certified by NIST for one or more quantities of interes

SRMs represent one of the primary vehicles for disseminatin

measurement technology to industry.”

Standard uncertainty – The uncertainty of the result of a measuremen

expressed as a standard deviation. (GUM, 2.3.1)

Standardization – See: self-calibration.

Systematic error – A systematic error is the mean of a large number o

measurements of the same value minus the (probable) true valu

of the measured parameter. (VIM, 3.14) Systematic error causes th

average of the readings to be offset from the true value. Systemat

error is a measure of magnitude and may be corrected. Systemat

error is also called bias when it applies to a measuring instrumen

Systematic error may be evaluated by Type A or Type B method

according to the type of data available. Note: Contrary to popula

belief, the GUM specifically does not replace systematic error wit

either Type A or Type B methods of evaluation. (3.2.3, note) S

also: bias, error, correction (of error) Compare with: random erro



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System owner – The person responsible for the availability, and

maintenance of a computerised system and for the security of the

data residing on that system.

Test accuracy ratio – (1) In a calibration procedure, the test accuracy

ratio (TAR) is the ratio of the accuracy tolerance of the unit under

calibration to the accuracy tolerance of the calibration standardused. (NCSL, page 2)

TAR = UUT_tolerance

STD_tolerance

The TAR must be calculated using identical parameters and units

for the UUC and the calibration standard. If the accuracy tolerances

are expressed as decibels, percentage, or another ratio, they must

be converted to absolute values of the basic measurement units.

(2) In the normal use of IM&TE items, the TAR is the ratio of

the tolerance of the parameter being measured to the accuracytolerance of the IM&TE. Note: TAR may also be referred to as the

accuracy ratio or (incorrectly) the uncertainty ratio.

Test uncertainty ratio – In a calibration procedure, the test uncertainty

ratio (TUR) is the ratio of the accuracy tolerance of the unit under

calibration to the uncertainty of the calibration standard used.

(NCSL, page 2)

TUR = UUT_tolerance

STD_uncert

The TUR must be calculated using identical parameters and units

for the UUC and the calibration standard. If the accuracy tolerances

are expressed as decibels, percentage, or another ratio, they must be

converted to absolute values of the basic measurement units. Note:

The uncertainty of a measurement standard is not necessarily the

same as its accuracy specification.

Third Party – Parties

Tolerance – A tolerance is a design feature that defines limits within

which a quality characteristic is supposed to be on individual parts;

it represents the maximum allowable deviation from a specified

value. Tolerances are applied during design and manufacturing. A

tolerance is a property of the item being measured. Compare with:

specification, uncertainty



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Traceable, traceability – Traceability is a property of the result of

measurement, providing the ability to relate the measurement resu

to stated references, through an unbroken chain of comparison

each having stated uncertainties. (VIM, 6.10) Traceability is

demonstrated or implied property of the result of a measuremen

to be consistent with an accepted standard within specified limiof uncertainty. (NCSL, pages 42–43) The stated references ar

normally the base or supplemental SI units as maintained by

national metrology institute; fundamental or physical natura

constants that are reproducible and have defined values; ratio typ

comparisons; certified standard reference materials; or industr

or other accepted consensus reference standards. Traceabilit

provides the ability to demonstrate the accuracy of a measuremen

result in terms of the stated reference. Measurement assuranc

methods applied to a calibration system include demonstratio

of traceability. A calibration system operating under a program

controls system only implies traceability. Evidence of traceabilitincludes the calibration report (with values and uncertainty

of calibration standards, but the report alone is not sufficien

The laboratory must also apply and use the data. A calibratio

laboratory, a measurement system, a calibrated IM&TE,

calibration report, or any other thing is not and be traceable to

national standard. Only the result of a specif ic measurement ca

be said to be traceable, provided all of the conditions just listed ar

met. Reference to a NIST test number is specifically not evidence o

traceability. That number is merely a catalog number of the specif

service provided by NIST to a customer so it can be identified o

a purchase order.

Transfer measurement – A transfer measurement is a type of method tha

enables making a measurement to a higher level of resolution tha

normally possible with the available equipment. Common transfe

methods are differential measurements and ratio measurements

Transfer standard – A transfer standard is a measurement standard use

as an intermediate device when comparing two other standard

(VIM, 6.8) Typical applications of transfer standards are to transfe

a measurement parameter from one organization to another, from

a primary standard to a secondary standard, or from a secondar

standard to a working standard in order to create or maintai

measurement traceability. Examples of typical transfer standard

are DC volt sources (standard cells or zener sources), and singl

value standard resistors, capacitors, or inductors.



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Type A evaluation (of uncertainty) – Type A evaluation of measurement

uncertainty is the statistical analysis of actual measurement results

to produce uncertainty values. Both random and systematic error

may be evaluated by Type A methods. (GUM, 3.3.3 through

3.3.5) Uncertainty can only be evaluated by Type A methods if

the laboratory actually collects the data.Type B evaluation (of uncertainty) – Type B evaluation of measurement

uncertainty includes any method except statistical analysis of

actual measurement results. Both random and systematic error

may be evaluated by Type B methods. (GUM, 3.3.3 through 3.3.5)

Data for evaluation by Type B methods may come from any source

believed to be valid.

Uncertainty – Uncertainty is a property of a measurement result

that defines the range of probable values of the measurand.

Total uncertainty may consist of components that are evaluated

by the statistical probability distribution of experimental data

or from assumed probability distributions based on other data.Uncertainty is an estimate of dispersion; effects that contribute

to the dispersion may be random or systematic. (GUM, 2.2.3)

Uncertainty is an estimate of the range of values that the true value

of the measurement is within, with a specified level of confidence.

After an item that has a specified tolerance has been calibrated

using an instrument with a known accuracy, the result is a value

with a calculated uncertainty. See also: Type A evaluation, Type B

evaluation

Uncertainty budget – The systematic description of known uncertainties

relevant to specific measurements or types of measurements,

categorized by type of measurement, range of measurement, and/

or other applicable measurement criteria.

UUC, UUT – The unit under calibration or the unit under test – the

instrument being calibrated. These are standard generic labels for

the IM&TE item that is being calibrated, which are used in the text

of the calibration procedure for convenience. Also may be called

device under test (DUT) or equipment under test (EUT).

Validation – Substantiation by examination and provision of objective

evidence that verified processes, methods, and/or procedures are

fit for their intended use.

Verification – Confirmation by examination and provision of objective

evidence that specified requirements have been fulf illed.

VIM – An acronym commonly used to identify the ISO International



200

Vocabulary of Basic and General Terms in Metrology. (The acronym

comes from the French title.)

Work Instruction – In a quality management system, a work instructio

defines the detailed steps necessary to carry out a procedure

Work instructions are used only where they are needed to ensur

the quality of the product or service. The level of education antraining of the people with the usual qualifications to do th

work must be considered when writing a work instruction. In

metrology laboratory, a calibration procedure is a type of wor

instruction.

1. Bucher, Jay L. 2004. The Metrology Handbook. Milwaukee: ASQ

Quality Press.

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