safety control systems conference 2015 - introduction to functional safety in gas detection (preeju)

Introduction to Functional Safety Standard for Gas Detection

Preeju Anirudhan (Instr. & Elec. Eng.)Product & Application Manager – Fire & Gas Detection SolutionsMarketing Manager – Chemical, Oil & Gas

Draeger Safety Pacific Pty. Ltd.

Preeju Anirudhan - Product & Applications Manager – F&G / Marketing Manager – Chem, Oil & Gas

Functional Safety – Fire and Gas Detection Systems

Objectives

Create awareness on

–The functional safety standards 60079-29-3 which applicable for fire & gas

detection to end-users.

–Why gas detection should not be clubbed together with Process Control

Standard IEC 61511 and the various standards applicable.

–Gas dispersion & placement of Gas detectors & role of gas detectors in risk

reduction.

–Technologies used in Flame & gas detection


1 Gas Dispersion & Sensor Placement2 Principle of Operation – F&G System

3 Risk reduction & Role of F&G detectors4 Functional Safety Standards for F&G and Projects.5 Decision Making on Type Of F&G System

6 Applications of F&G Detectors7 Why Using PLC's may generate trouble?


AGENDA


1 Gas Dispersion & Sensor Placement2 Principle of Operation – F&G System3 Risk reduction & Role of F&G detectors

4 Functional Safety Standards for F&G and Projects.5 Decision Making on Type Of F&G System6 Applications of F&G Detectors

7 Why Using PLC's may generate trouble?


AGENDA


Gas heavier than air:dense gas

Gas lighter than air:buoyant gas

Functional Safety – Fire and Gas Detection Systems Gas dispersion & Gas categories

HydrogenMethaneAmmoniaAcetyleneNitrogen

OxygenCarbon dioxidePropaneChlorineBenzenePhosgene

Gas behaving like liquids liquefied gas

Gas behave unpredictably gas jet elevated release


Different scenarios which are typical for gas leaks within a building

Functional Safety – Fire and Gas Detection Systems Gas dispersion in closed Rooms


Functional Safety – Fire and Gas Detection Systems Gas Dispersion


• The correct installation of gas sensors for the gas detection in outdoor areas is extremely important.

• Determining “what is to be protected” is important, i.e. people, process, asset and visualising the possible impact in the event of a gas leak/explosion.

• Environmental conditions can have a detrimental impact on the efficiency of the gas detection systems if care is not taken during the installation process.

• Sensors must be protected from weather conditions, e.g. heavy rains can splash more than 30Cm off the ground, so it makes sense for sensors to be placed above 30Cm when detecting heavy gases.

• Gas sensors should also be located downstream of prevailing winds; also consider the wind effects caused by buildings, tanks and other obstructions. Areas where wind changes directions during seasons will also need to be considered.

• Access to the detectors must be considered for ease of maintenance and use of remote sensors, remote calibration adaptors, remote display, remote bump-test adapter must be considered.

Functional Safety – Fire and Gas Detection Systems Placement of Gas detectors – Outdoor Environment


1 Gas Dispersion & Sensor Placement2 Principle of Operation – F&G System3 Risk reduction & Role of F&G detectors4 Functional Safety Standards for F&G and Projects.5 Decision Making on Type Of F&G System

6 Applications of F&G Detectors7 Why Using PLC's may generate trouble?


AGENDA


12

Functional Safety – Fire and Gas Detection SystemsGas & Flame Detection Methods & Principles of Operation

Gas•Infra red: Point & Open Path•Catalytic: Point•Electro-chemical: Point for Toxic gases & Oxygen•Laser: Open Path for Ammonia, H2S & CO2•PID: Point for VOC•MOS: Point for H2S –low humidity applications•IMS: Point for warfare gases•Paramagnetic: Oxygen (low/high)•Acoustic: for high pressure leaks (Ultrasonic)

Flame•UV•IR•Triple IR•UV-IR•Visual Flame (CCTV Flame)


FLAMEPROOF ENCLOSURE

MEASURING DETECTOR REFERENCE DETECTOR

BEAM SPLITTER

IR-SOURCES SAPPHIRE WINDOW

GASHEATED REFLECTOR

CH4

IR SOURCE GAS CUVETTE OPTICAL FILTER

Hydrocarbons absorb Infra-red light if present in the measuring area. The difference between the reference & signal is proportional to the amount of hydrocarbon or other gases present.

Functional Safety – Fire and Gas Detection SystemsPrinciples of Operation of Infra-Red Point-Gas Detectors


Functional Safety – Fire and Gas Detection SystemsPrinciples of Operation of Open Path Detectors (Flammable & Toxic)

Transmitter Receiver

An infrared/Laser beam (2 wavelengths) sent from TX to RXReference wavelength

Signal wavelength

Gas will absorb only the signal wavelength

Signal wavelength absorbed C

HH

HH

Reference wavelength unaffected

Receiver outputs a gas reading

Pulsar 1 Pulsar 2Pulsar Duct


Functional Safety – Fire and Gas Detection SystemsPrinciples of Operation of Catalytic Sensors

Wheatstone bridge

uBridge

Rth R2

R1Rref

HEAT Oxidation leads to energy release

The resulting heat is proportional to the amount of reactions per time

Temperature increase can be measured as resistance change of an embedded platinum coil and is proportional to the flammable gas concentration.

The resulting heat leads to a temperature increase ∆T

The resulting heat is proportional to the amount of flammable gas molecules


Electrochemical SensorsPrincipleA chemical reaction of the target gas with the electrolyte produces electrons (current) which is proportional to the gas concentration.

Why?Electrochemical sensors are very specific in general to the target gases and measure gases or vapours of very low concentration of gases that are difficult to measure using catalytic or Infra red type gas detectors.

Very low levels alarms to comply with exposures

Functional Safety – Fire and Gas Detection SystemsPrinciples of Operation of Electro-Chemical sensors


1 Gas Dispersion & Sensor Placement2 Principle of Operation – F&G System3 Risk reduction & Role of F&G detectors4 Functional Safety Standards for F&G and Projects.5 Decision Making on Type Of F&G System6 Applications of F&G Detectors



AGENDA


risk

Risk – ignition from non-Ex rated equipmentdangerous

safe

necessaryrisk reduction

actual risk reduction

tolerable risk

Functional Safety – Fire and Gas Detection SystemsRisk reduction & role of Fire & Gas detection.


risk

Risk – ignition from non-Ex rated equipmentdangerous

safe

Air inlet positioning

Ventilation rate

emergency shut-down

Gas Detection

residual risk

riskreduction

necessaryrisk reduction

actual risk reduction

tolerable risk



risk

dangerous

safe

Gas Detection

residual risk

Risk – ignition from non-Ex rated equipment

riskreduction

necessaryrisk reductionactual risk

reduction

tolerable risk




4 Functional Safety Standards for F&G and Projects.5 Decision Making on Type Of F&G System6 Applications of F&G Detectors



AGENDA


Functional Safety – Fire and Gas Detection SystemsWhat IEC 61508 Standards says

The scope of IEC 61508 ( Part-1,Clause 1.1)

…….A major objective of this standard is to facilitate the development of application sector international standards by the technical committees responsible for the application sector. This will allow all the relevant factors, associated with the application, to be fully taken into account and thereby meet the specific needs of the application sector. ……….

Old Edition and NEW Edition


Functional Safety – Fire and Gas Detection Systems Functional Safety Standards & where gas detection fits

IEC 61508Generic

IEC 62061Machinery

IEC 61513Nuclear

EN 50126Railway

IEC 61511Process

BS EN 50402 IEC 60880 Ed 2prEn 50495 IEC 60079-29-3


Functional Safety – Fire and Gas Detection SystemsGas Detection Standards - Explained

EN 50402 : 2005 (2013) IEC 60079-29-3

A Product based standard for the Manufacturers

A life cycle approach for the system designer, engineering contractor, installation, start-up, service, modification and decommissioning

Includes some good guidance of the special requirements in the world of Gas Detection

An entire Clause describing the special requirements of gas detection

Mandates the need for a R&D facility to operate under a functional safety management system

Mandates the need for everyone involved with the life cycle to operate under a functional safety management system


Functional Safety – Fire and Gas Detection SystemsVarious Standards for Fire & Gas Detection Systems

EN 60079 – 10 -1:2009 (EN 1127-1 : 2011)

ISO 31000 : 2009

BS 6079 -1 : 2010

EN 60079 – 1 : 2007

IEC 60079 – 29 – 1 : 2007

IEC 61508 : 2011

EN 60079 – 19 : 2011

• Standards for specifying the hazardous locations

• Standards for Risk Analysis

• Standards for Project Management

• Standards for Product design with respect to Ex areas

• Standards for Product performance

• Standards for Product Integrity and associated QA systems

• Standards for repair workshops


Functional Safety – Fire and Gas Detection Systems Explosive atmospheres – 60079 Part 29-3:

Guidance on functional safety of fixed gas detection systems –

This International standard gives guidance for the design and implementation of a fixed gas detection system, including associated and/or peripheral gas detection equipment, for the detection of flammable gases/vapours and Oxygen when used in a safety-related application in accordance with IEC 61508 and IEC 61511. This International standard also applies to the detection of toxic gases.

Other parts of this international standard and pertinent local, national and international standards separately specify the performance requirements of a gas detector and a gas detection control unit (logic solver). These standards are commonly known as Metrological Standards and are concerned with the accuracy of the measured value, the overall system performance, but not the device or system integrity with respect to the safety function. This international standard applies to the integrity of the safety function.


Functional Safety – Fire and Gas Detection Systems Standards currently applied in Projects

Project

Products developed under IEC 61508Application standards written

within the framework of IEC 61508

Machinery safety delivered under IEC 62061

Process safety delivered under IEC 61511ANSI/ISA 84.00.01

Fire and Gas Detection Systems


Functional Safety – Fire and Gas Detection Systems Standards that shall be followed in Projects

Project

Products developed under IEC 61508Application standards written

within the framework of IEC 61508

Machinery safety delivered under IEC 62061

Gas Detection delivered under BS EN 50402 / IEC 60079-29-3ANSI/ISA 84.00.07 Fire & Gas

Process safety delivered under IEC 61511ANSI/ISA 84.00.01


Functional Safety – Fire and Gas Detection SystemsInterpretation of Standards

General Understanding Actual Requirement

A Fire & Gas control circuit includes a detector, a control card and an output device

A Fire & Gas control loop includes performance approved detectors, performance approved control cards and output devices

The wiring diagram and the Cause & Effects chart are identical

The Ex zoning and the use of Intrinsically Safe isolators does not change

The Control System is programmed using competent engineers using Ladder Logic

Programming is not allowed(Competency would show that programming is not allowed and performance approved equipment is a pre-requisite)


Functional Safety – Fire and Gas Detection Systems Importance of Performance Approvals

What needs performance approval?

Why need performance approval?


1 Gas Dispersion & Sensor Placement2 Principle of Operation – F&G System3 Risk reduction & Role of F&G detectors4 Functional Safety Standards for F&G and Projects.

5 Decision Making on Type Of F&G System6 Applications of F&G Detectors7 Why Using PLC's may generate trouble?


AGENDA


Functional Safety – Fire and Gas Detection SystemsDecision path - Types of Fire and Gas detection system

Is there a statedSafety function

&Safety integrity?


The definition of a Standard Fire and Gas detection system is

– A system who’s specification does not detail a contribution to ‘risk reduction’

– A system which alarms only, with no supporting operational measures which

are announced as ‘risk reduction’

– A system which is not guarded against modifications

– A system which has no mandatory service and proof test intervals

– A system which is not supported by a fixed spare parts list for inspection,

maintenance and repair

Functional Safety – Fire and Gas Detection Systems Standard Fire and Gas detection system


Functional Safety – Fire and Gas Detection SystemsF&G Classification – Protection, Mitigation or Safeguarding system

The definition of a Fire and Gas detection system having a Protection function

• A Protection system reduces the frequency of the hazard

The definition of a Fire and Gas detection system having a Mitigation function

• A Mitigation system reduces the consequence of the hazard

The definition of a Fire and Gas Safeguarding system is• An additional system which operates in parallel to the SIS


The definition of a Fire and Gas detection system having a ‘function of safety (safety requirement specification)

– A system who’s specification includes a contribution to ‘risk reduction’• Safety Integrity level

– A system which alarms only, but is supported by operational measures which are announced as ‘risk reduction’

• Safety Integrity level and Operational procedures

– A system which is fully supported by a service regime, proof test interval and supporting documentation for spare parts interchangeability

– A system which is guarded against unauthorised modification

– A system who’s life cycle is supported by a Functional Safety Management system

Functional Safety – Fire and Gas Detection SystemsSafety Function - Fire and Gas detection system


• The speed of response of the sensing element (proof test)

• Alarm philosophy

• The trip level for a specific measuring point

• The action required behind the trip point

• The time taken for the action to be complete

• The required integrity of the complete safety function

• The operational procedures

• Environmental conditions

Note : sensor coverage or mitigation effectiveness is not part of the safety function

Functional Safety – Fire and Gas Detection Systems Criteria of a Safety Function


1 Gas Dispersion & Sensor Placement

2 Principle of Operation – F&G System3 Risk reduction & Role of F&G detectors4 Functional Safety Standards for F&G and Projects.

5 Decision Making on Type Of F&G System6 Applications of F&G Detectors7 Why Using PLC's may generate trouble?


AGENDA


Functional Safety – Fire and Gas Detection Systems Applications using gas detectors.

Detection of Hydrocarbons(oil & gas/Chemical/manufacturing)

Detection in 0 – 100% LEL

Leak Detection (Analyzer rooms/labs/solvent storage)

Detection in PPM /0 – 10% LEL


Functional Safety – Fire and Gas Detection Systems Applications for monitoring Flammable gases at heights

Special attention must be paid when installing gas detector at heights. E.g. •At entrance of air intake ducts.•Inside air intake ducts•Under ceiling or roof space at heights for CH4 detection in storage facilities & turbine rooms.•Cost of maintenance (scaffolding/ cherry picker/height safety permits)

Solutions:-Select performance detectors which has remote test/maintenance/calibration features, so basic maintenance can be performed without direct access to the sensor.


Functional Safety – Fire and Gas Detection Systems Applications for monitoring Flammable gases at Depths (confined Space)

Special attention must be paid when installing gas detector at depths or confined spaces. E.g. •In confined spaces (sumps)•Drains /Well heads/collection points•Tank Bund walls subject to flooding.•Cost of replacement due to water damage, CSE extra permits)

Solutions:-Select performance approved detectors which has remote test/maintenance/ calibration features, so basic maintenance can be performed without direct access to the sensor. Ensure the sensors are suitable for the application and can withstand flooding/submersion (IP 67/68)


Functional Safety – Fire and Gas Detection Systems Applications – inline monitoring

When designing Sampling systems, consider the following•Delay for gas transit•Ensure proper flow for reliable gas reading.•Ex-Approvals all the equipment used in the system.•Calibration of gas sensors inline. •Easy access for maintenance (cleaning/replacements)•Process conditions (heat/ humidity/ temperature/ Pressure /corrosion)•Sample Conditioning as required.



4 Functional Safety Standards for F&G and Projects.5 Decision Making on Type Of F&G System6 Applications of F&G Detectors7 Why Using PLC's may generate trouble?


AGENDA


– SAFETY may be compromised because the programming is open to the programmer. Plant operations may be affected due to false alarms.

– Analogue input channels need to be configured correctly to recognise the Special signals of Fire & Gas detection transmitter (0 – 4mA & 20 – 22mA)

– PLC’s are not designed for gas detection applications with respect to the International Standards for gas detection systems

– PLC’s does not have local displays to indicate gas readings – only external viewing panels are available which require configuration

– Gas detection system manufacturer has no control on PLC quality, availability, obsolescence, pricing etc.

– Skilled engineers are not always available and our tech support do not support PLC based central control systems

Functional Safety – Fire and Gas Detection Systems Why using a PLC can generate trouble?



Thank youPreeju Anirudhan - Product & Applications Manager – F&G / Marketing Manager – Chem, Oil & Gas

Email: [email protected]

mailto:[email protected]

mailto:[email protected]

safety control systems conference 2015 - introduction to functional safety in gas detection (preeju)

Presentations & Public Speaking