nabl news letter 40
DESCRIPTION
NABL NEWS 40TRANSCRIPT
Report on the Results o/Assessor Responses Receiued forExercise # 2 : Judging Compliance with the Requirements
NEWS ll
:
of ISO/IEC 77O25 (7999)Intrcduction
In the spring of 2004, AZLA provided allILAC signatoriesand appligants with an exercise *2 that would challenge
the signatories laboratory assessors to determine if thesituations described in the exercise were complaint or non-compliant with the requirements of |SO,4EC 77 O25 (1.999).
(ln 2002,ISRAC provided the first exercise on judging non-conformities.) Both exercises were done to determine thedegree of uniformity between the assessors used by thedifferent ILAC laboratory accreditation bodies and to alloweach accreditation body to look at the results from withintheir own group of surveyed as-sessors.
Five situations were described in Exercise 2 Each situationcontained information gathered at an assessment for whicha non-conformity (NC) against the requirements of ISO/IEC77O25 might be raised. The assessors were to examsituation carefully, and then take one of the following
a) If they thought there was sufficient evidence to raisea NC, they would mark tl-re NC box with an X and
mark the text box with the clause (or sub clause) of
ISO,/IEC 17 025 against which the NC had been raised.
b) If they did nof think there was sufficient evidence toraise an NC, they would mark the observation box
with an X. In the text box, they would mark therelevant clause (or sub clause) of ISO,ziEC 17 025 andstate iheir reasons for drawing the observation and
state what further evidence they would need to seek.
The following table identifies the participating ILACaccreditation bodies and the number of their assessors whoresponded.
Accreditation Body # Assessor: Comments
Ema Mexico I This may have been a
collective response
t.lA Norway o
$AC.Singapore o
ttdgL tnoia 43
SAS Switzerland tz
JAB Japan 15
NATA Australia 29
DMSC Thailand ZU
RvA Netherlands 17
lA Japan 69
OAA Argentina 1 This was a collective
response
ISRAC lsrael 15
PCA Poland 60
KOLAS Korea 18
UKAS United Kingdom 30
DACH/DASMIN Germanr 8
DAP Germany B
IANZ New Zealand 11
BMWA Austria 35
Cgcre/f nmetro Brazil /o
HKAS Hong Kong 1 This was a collective
response
Totals :
21 Accreditation Bodies 481
,. /
'ifI
Resulfs
There did not appear to be a great deal of misunderstanding
about the situations that were described for each of thefive scenarios. In most cases, the a.ssessors properlyinterpreted each situation. In several cases, the assessors
did not carefully read the scenario and so their responses
were off the mark. The assessors offered an array ofresponses with respect to the relevant clauses of ISO,zIEC
77025 that should be cited. There was also disparity in thedecisions reached between assessors concerning whethera situaticjn resulted in a deficiency or an observation. Therewas little consistency between the 48 1 assessors or between
the assessors within each accreditation body, except inthose cases where a collective response was received.
Each scenario is restated below, just as it appeared inExercise 2.Then the "expected response" (as determinedby the exercise creator) is stated for each scenario.Following that is a brief summary of the types of answers
that were received and specific comments if any particulartrends were seen. The percentages are based on the totalnumber of assessors that reported the required informationfor each scenario.
This report has been submitted to the ILAC AccreditationIssues Committee for a decision on anv further actions thatmay be needed.
EXERCISE # 2
Scenorio | :
At a small, privately-owned testing laboratory, the assessor
noted that a client was visiting the laboratory to monitorthe conduct of his testing. When the assessor questionedthe laboratory's quality manager about procedures forallowing their client to monitor their own test processes,
the quality manager replied that no procedures had beenprepared.
Expected Response:
The assessor in this example asked the laboratory rep fora proc.edure t'or allowing their client to monitor theirown test processes.
The most relevant section of ISO,/IEC 17025 is clause 4.7.
There is no requirement in clause 4.7 Ior any kind of writtenprocedure for allowing their client to monitor their own
test processes, so this would be an obseruation.
The assessor could seek further evidence of compliance
with clause 4.7 by observing the visiting client to see ifappropriate cooperation was given by the laboratory and
to see if confidentiality of other clients' work was being
maintained per section 4.1.5c of ISO/IEC 17025.
Summary of the Responses Receiued for Scenario #7 of Exercise 2 by IIAC
Specific Cotntnents :
10 assessors did not give a response to this scenario.
10 assessors cited Note 1,A under section 4.7. Notes are
not normative text.
Many of the assessors cited the need for a writtenprocedure, especially to address confidentiality or contract
review. Others cited issues with access to laboratory areas.
Surntn ary of N ABL Assessor's Response.
% Citing an NC 41%
% Citing an observation 59%
% Marking the most
relevant clause, 4.7
56%
Other clauses cited 4.1.4, 4.1.5 b,c,d; 4.2.1: 4.2.2: 4.2.3
4.4.1 : 4.4.2: 4.8: 5.3.2; 5.3.4; 5.4.7 .2 b
s.8. 5.8.1
% Citing an NC 42%
% Citing an observation 58%
% Marking the most
relevant clause. 4.7
74%
Other clauses cited 4.1.5c, d, 4.2.1 , 4.2.3; 4.4.1: 5.4.7.2b:
5.8
\>-
I
A
\
NC OBSERVATION
Scenario 2
Topnotch Laboratory is an in-house laboratory that supports
an automotive manufacturing company' Topnotch
Laboratory's Technical Manager resigned three months
prior to the on-site assessment. Until a suitable replacement
can be found, the manager of the Topnotch Production
Facility has assumed the duties of the technical manager'
He is ultimately responsible for the production line' the
laboratory that tests samples from the production line' and
the data from these tests that accompanies each production
shipment. The management system documents do not
address this temporary situatton'
Expected ResPonse :
Of immediate concern is the need for the laboratory to 1W"
define the responsibilities of the Technical Manager/ go"/"
production Manager in order to identify potential conflicts Bo"/"
of interest. 7o"/"
60"kThe most relevant section of ISO/IEC 17025 is clause
uo..^4.1.4. 4O"k
Per 4.7.4,this relationship must be defined and the scenario 3o"k
states that there are no management system documents to 2o"/"
address this temporary situation, so this would 6e a non- 1o"/"
conf ormitY. O"/"
Summary of the ResPonses
2 of Exercise2bY ILAC.Received for Scenario t
Specific comments:
5 assessors did not give a response to this scenario'
4 assessors cited Note 1 or Note 2 under section 4 1 4
Notes are not normative text
Many assessors cited clauses relating to the appointment
of deputies. or the technical knowledge of the production
manager
Summary of NABLAssessor's Response
RELAVANT
CTAUSE
3
% Citing an NC B4"k
% Citing an observation 16%
% Marking the most
relevant clause, 4.1.4 49"k
Other clauses cited 4. 1 . 5 a, b,c,d, e,f ,h,i, 4 -2-2: 4.2.4, 4.3 -3',
4 9.1: 5.2.1; 5.2.3; 5.2-4; 5.2.5: 5-3-4
% Citing an NC 91"k
% Citinq an observation 9"/"
% Marking the most
relevant clause, 4.'l .4 47"/"
Other clauses cited 4.1.5 a,b,c,d,t,h,i; 4.2.2; 4.3-3; 5.2;
5.2.1
OBSERVATION
Scenario 3
During an assessment, a production engineer from a metalsfabrication company entered its in-house laboratory andasked a laboratory technician for a microm eter. He neededto do a quick measurement of a sheet of steel to be used inthe fabrication machine. He took the micrometer out tothe shop floor, performed his measurement, came backinto the laboratory and returned the micrometer to thetechnician. The technician ran a quick check of themicrometer against a couple of his gauge blocks beforeusing the micrometer for his test measurements.
Expected Response
This scenario .is allowed per section 5.5.9 of ISO/IEC77O25, so the most relevant clause is 5.5.9.
There does not appear to be sufficient objective evidencein this scenario that a non conformity has occurred, thoughthe assessor would mosl assuredly have to investigate furtherto be sure, so this is an obseruation.
The assessor should seek further evidence of compliancewith the following clauses of ISO,zIEC 77025.
5.2.5 and 5.5.3, Find out if the production engineer wasauthorized to use the micrometer
5.5.6, Find out it' the correct procedures for handling,transporting and using measuring equipment exist and werefollowed by the production engrneer
5.5.10: Find out if the technician's quick check of themicrometer upon its return properly followed a writtenprocedure.
Summary of the Response Received for Scenario #3of Exercise 2 by Il"{C.
% Citing an NC 17%
% Citing an observatior 73/"
% Marking the mostrelevant clause, 5.5.9
48%
Other clauses cited 4.'f .5 a,e; 4.12; 5.2.2; 5.2.5: 5.3.45.4.1; 5.5; 5.5.1; 5.5.3;5.5.6; 5.6.3.15.8.1; 5.5.10; 5.6; 5.6.1
Specific Comments :
6 assessors did not give a response to this scenario.
Many of the assessors seemed most concerned about theproduction engineer's access to the laboratory. but it seemsclear that because the production engineer checked in withthe technician when he took and returned the micrometer,access by this production manager was not an issue forthis laboratory, under these circumstances.
Summary of NABL Assessors Response
2 assessors did not give a response to this scenario
4O"h''
300/"-
20"/"-
10%-
O"/" - NC OBSERVATION RELAVAN I
scenario 4 .LAUSE
This commercially available testing laboratory's procedure,SOP 17.8 states in section 5 - 7:
a) Every test item received from the clients shall be placedin a blue bin.
b) Each blue bin shall be tagged with the date and timeof sample submission, and a unique numericalidentification generated by the database.
B0%-]
7o%1
60%-]
50%--]
4
I
I
I
II
% Citing an NC 21"/"
% Citinq an observation 72"/"
% Marking the mostrelevant clause, 5.5.9
44"/"
Other clauses cited 4.1.5 a: 5.4.'l ; 5.5; 5.5.1 ; 5.5.2; 5.5.3;5.5.3.3;5.5.5; 5.5.6; 5.5.10; 5.6;5.6.1 ;
5.6.3.1
c) When not undergoing testing, all test items are to beslored in their bins.
During the assessment of this laboratory, the assessornoticed several test items on shelves at technicians'workstations; not in their bins. When asked, a technicianresponded, "Well, the items are on the shelf in the orderthat they came in- If we don't remove them from the bins,we end up with too many bins on the floor. We remove theitems in order and stack the bins. As we pull the samplesoff of the shelves, we know that the next sample goes withthe bottom bin!"
Expected response
This is first and foremost, an issue where the laboratory isnot following their own procedure for handling items.because the items are not kept inblue bins when not undertest; they are stored on shelves.
This would be a non-conformity against the laboratory'sown written procedure, SOP 17.8, sections 5-7. The mostrelevant section of ISOIEC 77O25 is clause 5.8.1.
The assessor would have to find further objective evidenceof item confusion in order to cite against 5.8.2 or 5.8.4.As the scenario is written, there is no evidence that thelaboratory's practice of keeping the items on the shelvesresults in any confusion.
Unless the assessor finds objective evidence of itemconfusion, the laboratory could simply revise their SOP 17.8to indicate the use of shelves rather than bins to resolvethis non-conformity.
Summary of the Responses Received for Scenario #4 of Exercise 2 by ILAC.
Specific Comments :
1 assessor did not give a response to this scenario.
Nearly 50% of the assessors cited either clause 5.8.2 or5.8.4, though the scenario did not state that the assessor
found any confusion in identification, or loss or damageof test items.
Summary of NABL Assessor's Response
\W" -90"/"
8O"/" -
7O"/" -60%-50"/" -
40"k -30"k -20"/" -
10% -o"k _
NC OBSERVATON *:ilXtt.
Scenario 5
The assessor at a small automotive testing laboratorynoticed during an assessment that a technician measuredthe thickness of the wall of a tube by using a micrometer(best reading 0.01 mm). For the final judgment, the meanvalue of 8 separate measurements was determined. In thetest report for this measurement, the laboratory included thefollowing statement under the "Conclusions" section of thereDort:
5
% Citing an NC 93"/"
% Citing an observation 70/
% Marking the mostrelevant clause. 5.8- l
26"/"
Other clauses cited 4.2.1: 4.2.2 d; 5.2.2;5.3.5;5.7; 5.7.3;
5.8: 5.8.2: 5.8.4
% Citino an NC 8'1"/"
% Citing an observation 19%
% Marking the mostrelevant clause, 5.8.1
11"/"
Other clauses cited 4. 1 5a,g; 4.2; 4.2.1 ; 4.2.'lb;4.2.2d; 4.3:4.3.1; 4.3.2.2b; 4.4.1b; 4.9; 4.9.1;4.1 0.1; 4.14: 5.2; 5.2.1, 5.2.2: 5.3.5;5.4; 5.4.1 ;5.5.4; 5.7 ; 5.7.3; 5.8; 5.8.2;5.8.4
The mean ualue of the wqll thickness of the tubes is
0.703 mm and lies aboue the required minimumthickness ot' O.7 mm.
Expected Response :
This scenario focuses around the test report issued by this
laboratory. Significant figures for the final reported number(mean value 0-703 mm) are not appropriate for themeasuring device used, and so the final reported result is
not accurate. Therefcire a statement of compliance cannot
be made.
This is a non-conformifg against clause 5.10.1 for reportinaccuracy and against 5.10.3.lb for the statement ofcompliance in the report.
The assessor would also need to confirm whethermeasurement uncertainty had been considered whenmaking the statement of compliance (5.10.3.1.c).
Summary of the Responses Received for Scenario #5 of Exercise 2 by IIAC.
% Citing an NC 62%
% Citing an observation 38%
% Marking the most
relevant clause, 5.1 0.1
or 5.10.3.1.b
4O"/"
Other clauses cited 4.1 .1 ; 4.4; 4.4.'l c; 4.1 0.1 ; 4.'l 2; 4.12.2;
5.1 .2; 5.2; 5.2.1 ; 5.2.2; 5.3; 5.4; 5.4.'l c;
5.4.2; 5.4.6.2; 5.4.7.1; 5.5.1; 5.5.2;
5.5.3; 5.6.2.2; 5.8; 5.9; 5.1O.2;5.10.2i;
5.'f 0.3; 5.'10.3.1d; 5.10.4.1b; 5.1O.4.2;
5.10.5
Specific Comments :
21'assessors did not give a response to this scenario.
Several assessors cited clauses relating to calibrationcertificates, even though this scenario refers to a test report.
Nearly 25o/o of the assessors cited clause 5.4.6.2 thoughthe scenario did not give any indication one way or theother whether measurement uncertainty had beenconsidered in the compliance statement.
9o/o of the assessors cited clauses relating to opinions and
interpretations, 5.10-5, although no opinion orinterpretation was provided in the report, merely a
statement of compliance.
Summary of NABL Assessor's Response
80"/"
7O"/"
60y"
50v"
407"
30%
2Oo/"
10%
6
% Citing an NC 63Y"
% Citing an observation 37o/o
% Marking the most
relevant clause. 5.1 0.1
5.10-3.1.b. 5.'l 0.3.1 c
37"/"
Other clauses cited 4.4c; 4.12: 5.2; 5.2.1: 5.4: 5.4.1
5.4.1 c; 5.4.2; 5.4.5.3; 5.4.6.2
5.4.7.1; 5.5.2; 5.10; 5.10.2i; 5.10.3
5.10.4.'l b; 5-10.4.2; 5.10.5
O"/"
Conclusions
There was a wide variety in the clauses of the ISO/IEC17O25 standard that were cited, sometimes with little logicin the selection made by the assessors- A review of "other
clauses cited" for each scenario will bear this out.
In many cases, a very broad section of lSO,/lEC 17025was cited, rather than a specifically relevant clause of the
standard. For example, section 5.8 was cited to indicate a
problem with item handling, rather than the specific clause
5.8.1. Section 4.2.1 was cited many times when adocumented procedure or policy was required or wasn't
being followed, instead of the specific clause in the standard
that was most relevant to the scenario. lt is most helpful to
our accredited laboratories to know exactly whichrequirement is being cited, so they know how to approachroot cause analysis and corrective actions-
It also ",r/tas
apparent that many assessors were citing non-conformity for the scenarios based on their assumptions
or expectations of the cause, reason or outcome of theobserved non-conformity, instead of citing the non-conformity for the situation at hand. Scenario # 4 is agood example of this. Nearly 5oo/o oI the assessors cited
clause 5.8.2 because they assumed there had to be a
problem with misidentification of test items, even thoughthe scenario never mentions that.
For ISO/IECL7O25z 2OO5Accredited Laboratories
Many customers of ISO,/IEC 17O25: 2005 accredited
laboratories are not aware of the dlf.ference between ISO
9001, 2000 certification and ISO,zIEC 17O25: 2005
accreditation. At times the laboratories themselves have
difficulty in determining whether they need certification,
accreditation or both.
To address this problem, on 1B'h June 2005, EO ILAC
IAF (lnternational Organisation for Standardisation,
International Laboratory Accreditation Corporation,
International Accreditation Forum) issued a JointCommuniqu6 on the 'Management Systems Requirements
of ISO/IEC 17025:2005, General Requirements for the
competence of testing and calibration laboratories' given
as under:
"A laboratory's fulfillment of the requirements ofISO/IEC 17O25:2OO5 means the laboratory meets
both the technical competence requirements and
management system requirements that arenecessary for it to consistently deliver technicallyvalid test results and calibrations- The management
system requirements in ISO/IEC 17025 (section 4)
are written in language relevant to laboratoryoperations and meet the principles of ISO9OOf :2OOO Quality Management Systems -Requirements and are aligned with its pertinentrequirements".
7
Voluntary Withdrawal of Accreditation
The following two laboratories has voluntary withdrawnthe Accreditation:
1
2
Indian Chains Private Limited, Kolkata
Cosme Pharma Pvt Ltd, Goa
Ca'libro'tion of Weights and lJncertainty ColculationsTripurari Lal, National Physical Laboratory, New Delhi
Ca'lihro,tion of aWeight
Calibration of a weight consists in assigning a mass valueto the weight by comparing it againSt a reference standardof known mass whose nominal mass is equal to that of theweight under calibration
This pomparison of the weights is done on a suitableweighing instrument. The indication of the weighinginstrument is used only to determine the difference betweenthe reference standard and the test weight
The comparison of two weights is always carried outaccording to the substitution method using ABBA or ABAweighing cycle to eliminate linear drift.
SubstitutionWeighing
The Reference Weight of known mass M* and the TestWeight of unknown mass Mw are put one after another onthe same weighing pan and their weighing difference Amis determined as :
Am : (M* - MR)
Weighing Cycles
For a single comparison, three internationally acceptedweighing cycles are used to eliminate linear drift of theWeighing Instrument. These are,
1. ABBA
2. ABA
3. A87B2... BnA
ABAWeighing Cycle
Remork: 7. The time interval between weighing shouldbe kept constant.
2. The above sequence may be repeated ntimes(n >1).
ABBAWeighing Cycle
Weight orPan
Balance
lndicationFirst
Diff.(B_A)
Second
Diff.(RA)
Mean
Diff.(B-A):
^mA
B
B
A
Il
l"+ L,
lr+ 2L,
In+34
[(lr-lr)+A [(r3 - 14)-A] (12 - Ir) + ns- I+)V2
B : A + [(1, - I,) + (Ir-In)l/2
Weight onPan
Balance
IndicationFrstDff.(B-A)
Second
Diff.(B.A)
Mean
Dff.(B-A)= Am
A
B
A
I1
lr+ L,
lr+ 2A,
[(1, - Ir)+ Al [(r2-13)-Al [(lz - (1, + lrl /21
B A + [(1, - (1, + l) /21
A
B' Represents Weighing
, Represents Weighing
Weighing Cycle
Weighing Cycle
Weighing Cycle
the Reference Weight
the Test Weight
Bt-ABt- ABr-A
ltbr _
ltbz _
ltbs _
I.r+ I u,lut r luzIu, + Iu,
A-r: A-z: A-j
/2/2/2
ABBA & ABA are used for. calibration of E and F Classof Weights and AB1B2, ... BnA for M Class of Weights
Weighing Equa};ion for Detertninortion of Mass
M* & p* : Mass & Density of the Reference weight
8
AB r.. B "A
Weig hing Cycl e
Weight on pan r Bl B. B3 B4 Bs n 86 B7 B8
Balance indicatior I, Io, lot Ius Ib4 Io, aZ Ib( Iot IA
M, & p, : Mass & Density of the Test Weight
P. , Density of air during the comparison
Difference in effective mass of the two weights
Mr (1- p^/h ) - MR( 1- p^/pR) : Amor
(Mr - Vrpu) - (Mn-Vnpu) : Am
Vr :Mr/p, ; V^:M*/p*Mr MR * (vT - VR ). p, + a,tn
This is theWeighing fuuationfor Mass Detennination
IJ n cei ointy C aI cul atio n s
The Weighing Equation for Determination of Mass of Test
Weiqht in air is :
Mass of the Reference Weight
Volume of the Reference Weight
Volume of the Test Weight
Density of Air, during intercomparison
Weighing dif.f.erence
InputQuantities
M.
VR
VT
pu
Am
Output Quantities
M* : Mass of the Test Weight
U* : Uncertainty of the Mass M,
The calculations of the best estimate of the mass of thetest weight and standard uncertainty associated with all inputquantities and the combined and the expanded uncertaintyof the output quantity are being given in the followingexampIes.
Mr:M*+ (Vr,V*).p..+Am
EXAMPIE 7
Suppose a 1 kg brass weight W of accuracy class F1 is calibrated against a stainless steel reference weight R of accuracy
class E2 on a 1kg single pan Mettler H-315 balance with readability 0.1mg. The calculations for mass, and uncertaintyassociated with it are as follows, -
Input quantities o'nd their uncertaintiesTest Weight
Density dw : 8 .4 g /cm3 ( for brass weight)
Volume Vw - 1 19.047 cm3 (calculated from density dw )
Exp.Uncertainty of volume Uvw : 0.001 cm3 (assumed value with k: 2)Standard uncertainty of Volume uu* : lJvw/ k: 0.000 5 cm3
Reference WeightMass
Expanded uncertainty of Mass
Standard uncertainty of Mass
Drift in mass of Ihe ref.erence
Standard uncertainty due to driftDensityVolumeExpanded uncertainty of volume
Standard uncertainty of VolumeConventional Mass
Expanded uncertainty of MrcStandard uncertainty of Mrc
:999.999 53: 0.000 09 g,k:2: Ur/k: 0.000 045 g: 0.000 01 s
(from calibration certif icate)(from calibration certif icate)
(from previous data)
(from calibration certif icate)(calculated from density dr )
( from calibration certificate)
(from calibration certificate)(from calibration certif icate)
MrUrur
DruDr
drwUvr
.uwMrcUrcur.
: Dr / {3 : 0.000 006 g ( negligible)
7'9 g /cms: 126.580 cm3: 0.000 5 cm3, k:2-- lJvr/ k: 0.000 25 cm3: 999.997 63 s
0.000 03 g: Urck: 0.000 015 g
9
Sensitit:ityWeight
Mass r. 5.008 mgExpanded uncertainty Um. : 0.001 mg , k:2Standarduncertainty uD.: tJm,/ k: 0.0005mg
Air Density
Measuring temperature, pressure and relative humidity ofair, the air density is calculated using BIPM Formula or airdensity table. Thus air density and uncertainty in itsmeasurement may also be treated as input quantities.
Temperature : 24.4oC ; Pressure : 7 4I.25 mm Hg;Rel. Humidity : 560/o
Air Density pu : 0.001 116 g/cmsStandard Uncertainty Upu : 0.000 05 g/cm3
Measurement Dsta
Mr - Mw: -2.10 mg Deviations: - 0.05 mgMr - Mw : -1.95 mg -t 0.10 mgMr - Mw: -2.10 mg - 0.05 mg
Iklecln : -2.O5 mg S.D: O.O9mg n:3
Am : (Mw- Mr) : 2.05 mg
OUTP UT QU ANTITIES AN D THEIR UNCER?AINTIES
Moss of the Test Weight
Mass Mw of the test weight W is given by the weighingequation (1) as follows.-
Mw : Mr + pu (Vw- Vr) + Am
: 999.999 53 g + 0.001 776 g/ cm3(779.047 - L26.58O )cm3 + 0.002 05 g
: 999.999 539 - 0.008.407 g + 0.002 05g: 999.993 77 g
Uncertainty of the moss of theTest Weight
TYPE A
Standard uncertainty due to weighing process ; -
'uA - s / ',1 n: 0.09 / 'l 3 :0.052 mg
TYPE B
(i) Standard uncertainty due to the reference standardis given by :-
u, : 0.000 045 g : 0.045 mg (from the input data)
u, : 0.00000fu : 0.006mg (from the input data-negligible)
u(m,) : 0.045 mg
(ii) Standard uncertainty due to buoyancy correction usingequation (9)
ub2 (Vw - Vr)2. u2 pa + ( u u*2 - u,,2) .pu2.
: (IL9.O47 cm3 - 126.0580 cm3)2 .( 0.00005g,/cm3)2+[ ( 0.00o5crn3)2 {0.00025crns) ? x (O.O OttL@/cnt\2
: ( 0.000 351 g)2
ub : 0.000 351 g : 0.351 mg
(iii) Standard uncertainty due to balance
For this balance, contribution in the uncertainty due tobalance will be the uncertainty due to its sensitivity anddue to display resolution. Other components i.e.uncertainty due to eccentric loading and due tomagnetism, will be negligible.
(a) The uncertainty due to sensitivity will be :-
u,: (Am) (u_./m,)
: 2.O5mg x ( 0.000 5 / 5.OO8) : 0.000 2 mg(from the input data- negligible)
(b) Uncertaintgr due to the display resolution
u d : (d / '16,i : 0.1 /'16: o.o+r mg
Total uncertainty due to balance
uu": {( u.2 + u62) : ./ (O.ooO 2)2 + (o.o4712)
: 0.041 mg
Totol Type B uncertainty
uB :./ (u.2 * uu2 + \u2): {((0.045 ms)2 + (0.351ms)2+ (0.0a1mg)?
: 0.356 mg
'\L i
10
Co mb ine d st an do'r d u ncert ai nty
u. : J( uoz + uu2 ) : r/ t (O.OSZmg)2+(0-355 mg)2 I :
Expanded UncertaintY
U kxu.: 2xo'36mg o'72mg
The input data are as follows:
Mass of the Reference weight
Drift in mass of lhe reletence
Density of the reference weight
Density of the test weight
Final Results :
0.36 mg Mass of the Test Weight is given by :
Mw = ( ggg-993 77 t O'OOO 72 ) s, k :2
2 x (0.36)a / (O.O52\4 : 2x2297 : 4s94 @
k:2U 2xO.36 mg : O.72 mg
EXAMPIE 2
u"a (m)v"fI : h- 7)
u-a (Lm)
Forv"r, : * :
Expanded Uncertainty
A test ueight of special steel with nominsl Mass of 7OO g is compared o,gainst a reference sto'ndo,rd on an
electronic bctlance of capacitg 2OO g uith readabilitg of o.o7 mg-
Mr: ( 99.999 86 t 0.000 02 ) s,k:2Dr : 0.000 01 g (from Previous data)
dr. : ( 3040 t 16) kg/mz ; k:2dw = (7900140)kg/m3 ;k:2
t1
llncertqintY Budget
Probabilitydistribution
O.O52 mg
NormalRectangular
Reference ueight,Mass
Drift in mass
Buoyancy Correction
NormalRectangular
Bo,lo'nce:SensitivityDisplay resolution
Totrrl Type B
Co mb in ed st an dard u n cert ainty
4
V,: 0.100 ks/BO4Okg/^3: 0.000 O72Mm3:72.M cm3
V*: 0.100 ksngoo kgl-3: 0.000 O72 66 m3 :12.66 cm3
M.:M, 1(V*-V,).pu+Am:9.999 86 g + (72.66 -L2.441cm3x 0.001 160glcm3
+ 0.000 09 g
99.999 86 g + 0.000 255 g + 0.000 09 g
Obseruations Dqtcr.:
Mw - Mr 0.09 mg
Mw - Mr 0.08 mg
Mw - Mr 0.08 mg
Mw- Mr
Mw- Mr
0.09 mg
0.11 mg
rd
:001 mg
Temp. 22.5"C; Rel.HumidiIy : 42 o/o
Pressure : 7 42.3 mmHg : 989.3 mbar
Fortnula toCo,lcula,te Air dursityp" : [0.34848P - O.OO9024 h e (0.0612 tt l/(273.15 + t)
P is pressure in mbar ; h is relative humidity in 0/o ;
T is temperature in oC
To calculate mass of the test weight and uncertaintyassociated with it.
Calculc,tion of Moss
Deuio,tions SguaresM* - M, : 0.09 mg 0.00 mg 0.0000M* - M,: 0.08 mg - 0.01 mg 0.0001
M* - M,: 0.08 mg - 0.01 mg 0.0001
M* - M,: 0.09 mg 0.00 mg 0.0000M* - M, : 0.11 mg +0.02 mg 0.0004
Mean: 0.09 mg 0.0000 ms 0.0006
Standard Deviation, o : { 0.OOO6/4mg : 0.012 mg
Am : (M* - M,) : 0.09 mg : 0.000 09 g
Mw:Mr + (Vw-Vr) .pu+Am
p" : [0. 34848 P - O.OO9O24 h e Q'0612 tt ]/( 27 3.I5+t)
: [0.34848x 989.3 -O.OO9O24x 42 e Q.o612x22'5tt l/(273.I5 + 22.5 )
: 0.001 160 g / cm3
-u[r
uv,
dr
: L2.44 x 0.001 : O.Ot2 S crn3
: (79OO t 40 )kg/ms , udr: @O /k)kg / m3: 20 kg / nts (k :21
(uo*/ d,: uvr / Vr ) or (20 /T7OO : ,vt / 12.66)
or(0.0025:uvr/12.66)
uv. :72.66 x 0.002 5: O.OS7 6 cm7
Standcrd uncertainfy ossocic ted with the airbuoyanay correction
,b2 : (V*'- Vr)2. ,2po * ( r u*, - uu,2) eoz: (72.66 - 12.++12. Q.067 mg / cm3)2 +
( 0.0316 cm3)2 - (0.012s cm3)2I x(1.160 mg / cm3)2 : 0.001351
un : O'O37 ^gStandard Uncertainty due to Display Resolutioiuo : (d / 2 | 3) x^,1 2: 0.01 ms / 2.4s _ o.oo4 mg
Toto,l Type B lJncertainty
uts ri ( ur2 * ut.2 + u,,2 )
: ^/[(0.012 mg)2 + (0.037 ms )z + (0.004)2] : V O.OOfSZg
us: O'O39 ^gCombined Stan dard IJ ncertainty
u.: {(uo2 + uu2) : .,/110 005 ms)z +(0.039 mdzl: O.OS9 mg
u.a (mr)\tqf :(n- 7) =4x(0.039)a/(O.OOS)+
u,,4 (Ltn)
: 14806 : -Expanded Uncertainty
U: kXU. : 2x 0.039 m9 : O.Og mgFinal Resulfs
M, : ( 100. 000 21 1 0.000 0s ) g
Combined stan dard uncertainty
Y "ff
= (n-I) xu.a (mr)
u,u4 (Lm)
For y "ff
:
Uncertainty
Uncertaintg Budget
4x(0.039)4 / (o.oo5)+ _ 4x3702 : 74806 @
: k :2
Probabilitydistribution
Sensitiuitycoeff icient
Stqndarduncertainty
mgWeighing process
O.OO5 mgReference weight:MassDrift in mass
NormalRectangular
Buoyancy Correction
Display resolution
Total Type B
Expanded 2 x 0.039 mg : O.O8 mg
13
The Colibr"qtion of BalqncesTripurari Lal, National Physical Laboratory, New Delhi
7. Introduction
This paper describes general procedure for the calibrationand the uncertainty of calibration of a weighing instrumentsused in a calibration laboratory for calibration of weights.An attempt has been made to arrive at an uncertainty whichcan be associated with the results of practical weighing.This is the uncertainty of weighing.
The '"yeighing instruments considered here are non-automatic, single interval instruments which includebalances and electronic apd mechanical industrial weighingequipment.
The test procedures used in the calibration are based onthose given in OIML Recommendation R76-7 and that forthe evaluation of uncertainty is based from the Guide tothe Expression of Uncertainty to Measurement (GUM).
2 Standord weights required
The series of weights required should cover the range ofthe weighing machine. Where a particular weighingmachine is used only over a very limited range it is possibleto reduce the number of weights required. If the design ofweighing machine requires a specific value of weight to be
Table
provided to set the weighing range, then this should alsobe provided, even if it is outside the limited weighing rangeas defined above.
Their buoyancy in the air in which they are used affectsthe apparent mass of weights used and this changes withthe air density. The calibration value of the weights needsto be certified for air density 1.2 kg m 3. If the buoyancyeffect caused by a different air density at the time of useleads to an error in the applied load that is greater thanone half of the resolution of the weighing machine beingcalibrated, a correction should be made-
Weighing machines as described in Table I can usually becalibrated using calibrated weights as per OIMLspecifications. The table assumes that the uncertainty ofcalibration of the weights used will be l/3 of its specifiedmaximum permissible error. In most cases it will be possibleto obtain smaller calibration uncertainties than this, and itmay therefore be possible to use a weight of a lower class.However, when selecting suitable weights, attention shouldstill be given to properties of the weights other thanaccuracy, such as magnetism, corrosion and wearresistance. In most laboratory applications, it would not be
apprcpriate to select a class lower than M1.
-7A possible selection table of weights for calibrotion of weighing mo'chines
Capacity Resolution
7OO g 7os 7g 7OO mg 7O mg 7mg O.7 mg <O.7 mg
Upto50g M3 M3 M3 M2 F2 E2 E1
Up to 100 g M3 M3 M3 M3 M1 F1 E1 E1
Up to 500 g M3 M3 M3 M2 F2 E2
Uptolkg M3 M3 M3 M1 F1 E1
Upto5kg M3 M3 M2 F2 E2
Up to 10 kg M3 M3 M1 F1 E1
Up to 50 kg M3 M3 F2 E2
Up to 100 kg M3 M1 F1
Up.to 500 kg M2 F2 E2
g[r
t4
3. Calibration Procedure
The documented procedure for calibration of a
weighing machine should include sufficientmeasurements to define the performance of thatmachine-
If the machine to be calibrated is a electronic, it has'internal calibration' facility that allows the outputof the machine to be adjusted between zero and aninternally or externally applied weight, in that case itis necessary to operate this facility prior to thecalibration, and also it should be operated regularlybefore the weighing machine is used.
For the balances having electronic display, sometimesthe reading is such that the last digit will flickcontinually between successive numbers When thishappens the reading used should be the mean of thetwo digits.
The procedure should include tests for the followingparameters, except where the construction or use
of the machine renders a particular test inappropriate:
Repeo,to'bility
The instrument should be set to zero before eachmeasurement. The load should be placed on-center.A one-piece test load should preferably be used. Forsingle range instruments, the test load P, should be
equal to Max/2. For multiple-range instruments,
P : Max, + (Max .*, - Maxrl/2.
All weighings involve a minimum of h,vo readings, azero reading and a reading with a weight to bemeasured- If this difference is measured a number oftimes it is a good measure of the repeatability of thereading. Usually a minimum of ten repeatedmeasurements are taken when calibrating weights upto 50 kg, and a minimum of five repeatedmeasurements when calibrating weights exceeding 50kg. fte balance should not be zeroedduring this series
of readings. It is not necessary for the weight used
for a repeatability test to be traceably calibrated-
Some times it may happen that same value of thedifferences may be obtained for all repeatedmeasurements. In that case standard deviation willbe zero.lt can be shown that if one of the n readingsdepart from zero by dx then the standard deviation isgiven by
s: dx,4n
If dx : 1 then for n:10, s : 1/,ll} = l/3(readabilityof the balance.)
Therefore to be realistic, the minimum standarddeviation of a balance should be one-third of itsreadability.
Sensitioity or Sco.le Vo,lues
It is the value of a scale division (not applicable formachines with digital displays) of the weighingmachine Measuring the sensitivity of the balanceallows a measured difference in terms of scaledivisions to be converted into a mass difference andis therefore vital to the use of the balance.
The sensitivity of mechanical weighing machinesgenerally changes with load, and it is thereforenecessary to measure the sensitivity at a load similarto that for which the machine is used. For a machineused across its range, it would be appropriate tomeasure the sensitivity with no load, loaded at halfits capacity and loaded at or near its full capacity.
For electronic balance with digital display the idea ofsensitivitgr needs to be modified slightly. The electronicdisplay covers the whole weighing range of thebalance and by adjustment, and the use of a standardweight, the display can be made equal to its nominalvalue at any point. At other points linearity and othererrors may cause the balance indication to departfrom nominal value. So rather than refer to sensitivifu
(b)
(o)
15
T
it is preferable to say departure of indication from
nominal value or linearity.
(c) Departure of indication from notnino,l uqlue
In this test the reading on the balance is checked at
sufficient equally- spaced steps over the range to
ensure that there is no possibility of the reading being
in error between points. Usually this covers at least
10 points, evenly spread over the range. For'machines that have internal weights (e.g. dial-up
weights) each weight setting should be tested. For
machines having more than one range, this test
should be carried out for each range used.
(d) Effect of Off-Centre Loading (Eccentricity)
This effect is assessed placing a weight of nominal
value between 7/4 and 1,/3 of the maximum capacity,
typically placed between 7/2 to 3/4 oI the distance
from the center of the load receptor to the edge, in a
sequence of center, front, left, back, right, center, or
equivalent.
It is not necessary for the weight used for the
eccentric-load indication test to be traceably
calibrated.
Hysteresis
Hysteresis is occurring when a balance, for the
application of the same weight, displays a different
reading when the load is ascending compared to when
it is being reduced. A simple check is as follows'
Incrementally increase the load by adding weights one
at a time, noting the balance reading after each
addition
2. Remove the weights in reverse order, noting the
balance reading after each removal
3. Compare the readings for the same load being applied
to the balance
Significant deviation between the increasing and decreasing
readings indicates a poorly adjusted or dirty balance
The laboratory should set the error allowed for a particular
machine, for a particular test, after considering the use to
which the rnachine is put. Manufacturer's specifications for
weighing machines will often be inappropriate for the
application.
In order to comply with the requirements of ISO,/IEC
77O25, the laboratory needs to ensure that a suitable
uncertainty of measurement is calculated for the weighing
machine calibration.
lJncertainty Euo,luo,tion in Co.librotion ofBo,loince
The main sources of uncertainties in calibration of
balances are as follows
7- Repeatability ( Tvpe A)
Repeatability of a balance is usually determined by
making 10 measurements at particular points across
the range of the balance and then calculating standard
deviation (s) of these 10 repeated measurement
results. This is Type A uncertaint5l and is given by :
uo : s,/ {n, n:10
2. Uncertainty in the Reference moss (TVpe B)
The standard uncertainty of the mass of reference
weight used in calibration is also contribute a Type B
(f)
component in uncertainty of the balance. It is given
in the calibration certificate of the reference weight.
Thus standard uncertainty due Io reference weight is
u*:U*/k
3. Resolution of the bo'lo'nce (Type B)
Resolution limitations in reading the scale or with a.' digital indication may contribute some uncertainty
which may be treated as rectangular distribution withinfinite degree of freedom. It is given by
uo: (d /2.'B)x^12
where the 2 in the numerator accounts for theresolution being a difference between the load reading
and zeroi.
4. Uncertainty due to drift in the m<rss vo,luesbetween calibrqtion (Type B)
If the reference standard used frequently in calibration
there is a risk that its certified values may change by
an amount approaching the uncertainty. If this driftis Dr then assuming rectangular distribution,uncertainty due to this drift is
uD,ift : Dr / 2',13
5. Drift in Sensitiuity due to temperature (Tqpe B)
Temperature effects on the scale sensitivity of the
balance. We need either the actual change in scale
sensitivity between the beginning and end of a
calibration or we assume the coefficient relating scale
sensitivity drift to temperature. The two possibilities
are :
u.".. : Sensitivity drift durlng cal.x mnge maxva\re/N3
Or
u,",, : Relating Coefficient x ( Max. - Min )
temperature x (range max) / 2 rl3
6. Uncertainty due to off center loo'ding
Off centering loading of the balance may be assessed
but not to be included as a component of uncertainty
as it is assumed that the operator may take all possible
precautions to minimize this affect.
7. Uncertainty due to hysteresis
This component may also be assessed but not to be
included as a component of uncertainty as it is
included in other contributions
8. Combineduncertainty
Total Type B uncertainty ue : !(un2 +uo2 +uonr,2 + u*rr2)
Combined uncertainty u. : {[ uo2 + uu2 I
9. kpanded uncertainty U: k. u^
E}{AMPIE
Cc'librcltion of a Bqlo;nce o 2OO g Electronic bollance
Data fron the bo,lo'nce specifications:
Max Capacity : 2lO g
Readability : 0.1 mg
Drift in balance indication : 2 ppm/"C
7. Repeatability ( Type A)
Choosing p: 100 g as test load and taking ten repeatedmeasurements as given in following table:
t7
Measurements Indications (I)(g)
Deviation (di)(mg) d12
1 100 000 0 + O.02 0.000 42 100.000 1 + 0. 12 0.0r4 4
J 100.000 0 + 0.02 0.000 4
4 99 999 9 0. 08 0.006 45 100.000 0 + 0.02 0.000 46 100.000 1 + 0.72 0.014 4.7
100 000 0 + 0.02 0.000 48 99 999 9 0. 08 0.006 49 99.999 B 018 o.o32 4
10 100.000 0 + 0.02 0.000 4
Mean 99.999 9a Sum 0.000 00 Sum 0.076 0
Standard Deviation s: vlo.ozo 0 / 9):0. 092 mg
Type A uncertainty is given by :
un: s,/!n :0.092/.,1 70:0.029mg,
2. Uncertainty in the Reference mass (Type B)
The relerence weight of 100 g is used to calibrate thetest weight . The uncertainty of the reference weightis Us : 0.000 020 g with k : 2
un : Us/k = 0.000 020 / 2 : 0.000 010 g : 0.010 mg
3. Resolution of the balance (Type B)
d:0.1m9
uo : (d /2 ^B ) x'12 : Q.l /2 r/S ) x ./2.
= O.0707/ ri3 mg: 0.041 mg
4- 'Uncertainty due to drift in the mass valuesbetween calibration (Type B)
If Dr = 0.000 015 g from the previous data thenuo,ift: 0.000 075/2\13 : 0.0075/ {3mg : 0.004 mg
5. Drift in Sensitivity due to temp.gqfure (Type B)
Given drift in balance indication with temperatureas 2 ppm/"C. For 1009 mass the coefficientrelating scale sensitivity drift to temperature
:2x1.06 x100 s/oC.Assuming temperature variation during calibration is
0.50C then
u.",,: 0-5x 2 x 10-6 x700 42: 0.10046/ {3 mg : 0.0
Total Type B standard uncertainty
ua = { (un2 * uo2 * uDr,f,2 + ur"n.2 )
= ! [(0.010)2 + (0.041)2 + (0.004)2 + (0.058)2 ]
= 0.072 ms
Combined uncertainty
u. :{[ t,A2 * ,82 ] :{l(0.029)2 + (0.072)21
U. : 0'078 mg
Expanded uncertaintyU:2x0.078g=0.16mg
6
,i\trd
7.
-"l
u.4 (mt)!
"ff: (n-7) x
u-a (Lm)
For tt"ff : : k :2Expanded Uncertainty
I - Cleaning with freshly prepared chromic acid then it is
1 aried thoroughly
o Er ' Set-up the balance in weighing condition and select
suitable standard weights, necessary for this calibration
work.
9 x(0.O72)s / (O.OZg)a : 9x38 : 342 6
U:2x0.078mg:0.16mg
after weighing (T2) is measured. Mean of these two
temperature is the temperature of the water (Tw).
The mass of water (Mw) contained in the measure up tothe mark is calculated using following relation:
Mw : ( I- p^/ p,) ( W1 -W2) i ( 7- p"/ p*)
, Cslibrstion of Volumetric MessuresTripurari Lal, National Physical Laboratory, New Delhi
,,rI., -----....--.-t^ r .r, . Thevolumeofwater,VmatthetemperatureTwisgivenby; {. Wciigh the empty measure and a standard weight ot
mass Wl (approximately equal to the mass of distilled Vm : Mw / p* -- ( 1- p^/p,). ( W1 - W2)/(p* - p^) ti" \water of nominal volume of the measure) The voiume Vm at th treference temperature 27"Cis given@;
. Weigh the measure fully filled-up with distilled water Vzt : Vm / 11* 0 ( I* - 27 )lWhere p is the coefficient of cubic expansion of the material
some required standard weights of mass W2
ure of distilled water before weighing (T1) and of the measure.
Uncertainty Budget
Typ. SourceVaIue
mgProbabilitydistribution Dioisor
Sensitiuitgcoeff icienl
Sto'ndorduncertainty
tng
Degree offreedom
A Repeatability 0,o29 Normal 1 I o.o29 9
B Mass of the reference
weight
0.020 Normal 2 1 0.010 @
B Drift in mass 0.0075 Rectangular ./ s I 0.004 €
B Display resolution 0.071 Rectangular '^/ s I 0.041 €
B Sensitivity variation 0.1005 Rectangular ^/ s I 0.058 €
Totc.l Type B : ^/
(u^' * ,o2 * up,,112 * ,,n,,.2 ) o.o72
Combined standard uncertaintv o.o78
t9
UNCERTAINTY CALCULATIONS IN VOLUMEMEASUREMENTS
The contribution factors in the uncertainty of the estimatedvalue of the volume of the measure is mainlv due to twosources of errors ,
1. Uncertaing due to weighing process (Type A).
2. Uncertainty due to the standard weight used in thecalibration process.(Type B).
Unce.rtqinty due to Weighing Process ( Type A )
The uncertainty in the weighing process is due to thevariability of the balance which is generally obtained fromthe past history of the balance using the same method ofweighing as used in this calibration procedure.
Suppose pre-established standard deviation of the balanceusing this method of weighing is s then type A standarduncertainty is given by :
un: o/!nwhere n is the number of observations taken to estimate o.
Uncettainty due to Stqndard Mo,ss (Type B)
Suppose the expanded uncertainty of the standard (S) used
in the above calibration is Us with coverage factor k:2,obtained from the calibration certificate of the standards, thenstandard uncertainty due to the standard weight will be ,
u":Us/k,Uncertainty due to other contribution factors such as
densities of the air . of the water and that of the materialof the standard weigh are very small and may be assumed
to be negligible.
Total type B standard uncertainty will be U- : u..
Combined standard uncertain$ u. = ! 1uo2" * ur2 )
Expanded uncertainty U :k.u. ;k: 2
EXAMPLE
Cc'libration of a 5O mI Volumetric Flaslc
Ref. xx xxx Case No. yyyyy Dated , DD/MMNY
Name and Address of the Customer : M,/s ABC
Date of calibration , DD/MM/YYRoom Temperature : 22.5oC Pressure : 986 mbar
R.H : 48.6 o/o
Air Density (p. ) : 0.0011 65 9 / cms
Temperature of water Initial (f1) , 22.3"C Final (.I2) 22.4oCMean (T) : 22.35oC -
Density of water at temp. T (pw ) -- 0.gg7 6932 g / , 3
Balance used , A single Pan Electronic Balance- MettlerReadability : 0.01 mg.
Pre-established standard deviation of this balance,o : 0.02 mg, n: 10
Standard Mass used ' 50 g and 25 mg weights withits mass values
Msr : (50.000 01 + 0.000 05) S ; k: 2 (from its calibrationcertificate)
Ms2 : e\.OI t 0.01) m g : k : 2 (from its calibrationcertificate
Mass of the empty vessel + standard weight(w1): 150 00152 g
Mass of the empty vessel + distilled water+ standard weight(w2) : 150 002 86 g
W1 : 50.000 019, W2: O.O25 019 (W1-W2): 49.975 s
Weighed mass of distilled water : (W1-W2) + (R2 - R1 )
: 49.975 g + 0.001 34 s : 49.976 34 g
Density of the standard used (p. ) : 8.000 9 / cms
The volume of water at the temperatureT : 22.35"C p : 0.000 027 /"C
Vm : ( I- p"/ p,) . (mass of distilled water) / ( p* - p")
= ( 1-0. 00 1 1 6518. 000) x49 x 97 6M / (0 .997 69 32- 0. 00 1 1 65)
: 0.99985437 5 x 49 x 97 6 Y/O.9965282 : 50. 7 43 7 5 qns
vzt: vm /|7+F(t - 27 )l : 50.143 LScm3/[1+ 0.000027 (22.35 -27 \l
1Al[i,1r
20
Vzz: 5O.743 27 cm3 / 0.9999163 : SO.7J7 cms
U N C ERTAI NTY CALCULATIONS
Standard Uncertainty Tgpe A ( due to weighingProcess)
uR : o / .'l n: O.02 mg/.110 : 0.006 mg
Stqndqrd Uncertainty Type B ( due to stbndard used)Us : (0.05 + 0.01) mg : 0.06 ms ; k :2 then
uB :u, : 0.06 mS/ 2 : 0.03mg
Stqndard Uncertainty Type B ( due to displayresolutiori)
ud - @/2 {3 ) x ./Z (a : 0.01 mg)= 0.004 mg
Total Type B sto,ndo'rd uncetto,intyuB : {t(o.oso)2+ (o.oo+)'l : o.o3omg
Combined Standard lJncertaintyu.:{(uo2*us2): {t (o.ooo)2 . io.osoP, : d.oso o *n
F-xprrnded uncertainty
U :k. v : 2x 0.0306*s: 0.0612mg: O.O6L2/ 0.997 6932 cm3
U: r O.O67cms
Final Resuffs Volume of the Volumetric Flask: (50.137 t 0.061) cm3, k:2
Uncertainty Budget
Combined Stondqrd lJncertainty Uc: { ( uA2 * ua2 ) = O.OSO 6 ^gD", (n- r) * u"or'l''. : 9x(0.0306)n /(o.ooolo : 6089 : *
u_a (Lm
For o"t/ - - : k :2Expanded Uncertainty lJ :2 x 0.0306 mg : 0. 061 mg : 0.06I/0.99T6982 cm3 : 0.061 cm3
Type Sources Estimated SfandardsUncertainty
Degree offreedom
Type A us
Due to Weighing ProcessuA = s/l ns : 0.02 mgn :10
O.OO6 mg 9
Type B utDue to Standard Ms1u"r = Usr/k :0.05 / 2mg
: 0.025 mg
Due to Standard Ms,u"2=Usullk :O.07/2 mg
: 0.005 mg
O.O3O mg
Type B uboStandard uncertainty due tobalance display Resolutionuo = (d / 2.,1 3lx,,l 2d : 0.01 mg
O.OO4 mg @
Total Type B O.O3O mg 6
2l
Guidelines fo, Calibro.tion of HydrometersTripurari Lal, National Physical Laboratory, New Delhi
A hydrometer is calibrated using the method of comparison
in which the hydrometer under calibration is compared with
reference to a standard hydrometer whose scale is precisely
known.
The hydrometers to be calibrated is floated in a liquid of
appropriate density which is so adjusted that the level ofthe liquid surface intersects the scale graduation under
examination. A similar standard hydrometer is floated
alongside and indication of its scale is observed carefully.
Differences between the scale reading of the standard and
under test hydrometer gives the correction to be applied in
the scale reading of the under test hydrometer to get itsactual value of the scale reading.
The following support equipment are required forCalibration of hydrometere using this procedure
1. The liquid is contained in a rectangular jar, with its
front and back walls being parallel. The front wall is
made of optical glass, which is plain and polished
from outside. This prevents the distortion of the image
of the scale of the hydrometer. Except for abnormal
hydrometer a jar of about 112 mm length, 62 mm
width and 360 mm height will be suitable toaccommodate two hvdrometers with stirrer and athermometer..
2. A stirrer is used to stir thoroughly the reference liquid
in the jar so that air may not be entrapped in the
liquid. The design of the stirrer is of the special type
having perforated rectangular metal sheet whose
dimensions are 2 mm less than the those of the cross
section of the jar. A stout rod is screwed in the center
of the metal sheet and works as handle.
3. A wooden rectangular board slightly wider than the
width of the jar, whose top half is painted black and
bottom half white. The line separating the black and
white portion is horizontal. The screen is movable
about its horizontal axis and it is placed behind thejar at an angle of 45o in such a way that lineseparating black and white portion is just below the
liquid surface. This screen helps in keeping the correct
line of sight.
4. A long total immersion thermometer graduated in
0.1oC with a calibration certificate of scale correction
is used to measure the temperature of the ref,erence
liquid. A thermometer oI range - 0.5 oC to 40.5oC is suitable for this purpose.
5. The hydrometer vessel set-up is installed in a closed
chamber equipped with exhaust system to suck out
fumes of the liquid used.
6. Because of the toxic nature of the liquids, the
atmospheric conditions are kept reasonably vapour
free using an exhaust system which draws the vapour
downwards, thus taking advantage of their highdensity.
The hydrometers are calibrated under normal roomtemperature conditions. Appropriate corrections are
applied for hydrometers graduated for density or relative
density at reference temperatures. These referencetemperatures are generally 20 oC, 15 oC, 15.5 oC orthat desired by the users.
The calibration is done in the following steps:
1. Clean all apparatus before use by a lint free cloth.
\
22
2. Allow the liquid to attain thermal equilibrium with its
surrounding and then pour it into the hydrometer
vessel fiar). Avoid the formation of air bubbles in the
liquid by pouring it down the side of the vessel. Stirthe liquid vertically with the stirrer, again avoiding
formation of air bubbles. Record the temperature of
the liquid nearest Lo O.2o C.
Insert the hydrometer to be calibrated, carefully, into
the liquid holding it by the top of its stem. Release
the'hydrometer when it is approximately in its state
of equilibrium. Adjust it so that the liquid surface level
intersects the scale graduation to be calibrated.
When the hydrometer is in steady state, press the
top of the stem downwards a few millimeters beyond
the position of equilibrium. Withdraw the hand and
observe the meniscus as the hydrometer oscillates to
equilibrium. If the stem and the liquid surface are
clean, the meniscus shape will remain unchanged as
the hydrometer rises and falls. If the meniscus shape
changes e.g. if it wrinkles or distorted by the motion
of the hydrometer, lack of cleanliness is indicated. In
such case the hydrometer and vessel should be cleaned
and the test is repeated with a fresh cleaned sample.
Insert a similar reference standard hydrometeralongside such that it may not touch the vessel walls
and the hydrometer under test. Repeat the step 4 forsetting this hydrometer also.
When the two hydrometers which must not be
touching each other and the side of the vessel, have
settled down to their equilibrium positions, record the
scale readings of both the hydrometers with the help
of a black and white screen behind the jar
If the liquid is transparent the scale reading is taken
corresponding to the plane of the intersection of the
horizontal liquid surace and the stem. When taking
the reading, view the scale through liquid, adjusting
the line of sight so that it is in the plane of the liquid
surface.
If the liquid is opaque, record the reading where the
meniscus merges into the stem of the hydrometer
Immediately after taking the reading as in step 6 or 7measure the temperature of the liquid to the nearest
O.2o C. The mean of this temperature and the initial
temperature referred in step 2 should be used tocalculate the correction due to temperature, ifrequired.
The difference between the initial temperature and
the final temperature should not exceed 1 oC and ifa larger difference is found, it indicates lack of thermal
equilibrium and in that case repeat the procedure from
step 2
Repeat steps 5 to B using the second reference
standard hydrometer at the same graduation point.
After recording the readings of the test hydrometer
and the reference hydrometers at all the graduatiohs
of the scale ( normally four graduation points are
taken) the following corrections are to be applied' -
Certif icate correct ions: Certificate corrections of
the reference hydrometers are taken from theircalibration certificates and are added algebraically to
the scale reading of the hydrometer under test, at
that particular point.
Tetnperature Correction If the two hydrometers
under comparison do not have the same reference
temperatures then their indications will differ by an
amount proportional to changes in their volumes
caused by thermal expansion of one with reference
83
4
5
6.
9.
10.
A.
23
IE
to the other. In such cases a temperature correction,
as given below, is applied to the indication of the
reference hydrometer to get the actual measurement
results , -
c : R.a (t.-t)
Where c : correction to be applied to the scale reading
of the reference hydrometer in g ,/ cm3.
R : density indication in g / cm3
a : coefficient of cubical expansion of glass or
the material of the hYdrometer
t. : reference temperature for which the
standard hydrometer has been calibrated.
t : reference temperature for which the
hydrometer under calibration is being
calibrated.
Forglassa : 25x\O4 /oC, then
Tr: surface tension of the liquid for which the
hydrometer has been calibrated (mN/m).
m: mass of the hydrometer in grams.
The term (n Rd / g.m) is called Surface Tension Factor
(STF) of the hydrometer
The STF depends upon the actual value of R (density
indication), but STF being very small, the middle value of
the range of the scale is taken as R.
If the hydrometer under test has Tu as its surface tension
while standard hydrometer was calibrated for surface
tension Ts and if the two are compared in a liquid of surface
tension T then surface tension corrections for these two
will be STFu (T-Tu) and STFs (T-Ts) respectively-
D. Meniscus Correction: In case of opaque liquids,
the scale reading is taken where the top of the
meniscus appears to meet the stem of hydrometer.
In order to obtain the corresponding indication at level
of the horizontal liquid surface, a correction called
meniscus correction (MC) has to be applied- This
correction is given bY :-
1000.i.oC: I! (1 + 2.g.d2.p0,21000o)-11 " '(4)
d'Po t"gwhere i : rale interval ( S ,/ cm3 1
o : surface tension of the liquid ( mN /m).
d : extemal diameter of the stem (mm) -
po : reading at lhe top of the meniscus (g/cm 3)
s : scale length (mm) .
g : acceleration due to gravity (m / s2l
(1)
c : 0.000025R (t"-t)
C. Surface Tension cortection: If a hydrometer is
used in a liquid whose surface tension is different from
the one for which the hydrometer has been calibrated,
then a correction called surface tension correction
has to be applied to the observed scale reading to get
the correct indication. This correction is given by :
c : [rc.R d (T - T1) X 10 3l / k.ml .... (3)
Where c : is the correction in g/cm 3.
R : density indication in g/cm3.
d : stem diameter of the hydrometer in mm
g : acceleration due to gravity ( m/s1
(2)
T : surface tension of the liquid used (mN ,/m).
24
For ready reference, the values of MC in kg/m3 havebeen tabulated below for various series of densityhydrometers conforming to BS 778 : 1979.
The scale lengths are given in third row and surface tensionin column 2 in units of mN/m.
Table 7
Meniscus co'rlction (MC) in kg/ms for oarious hydrometers.
leries of Hydrometer L20 L50 and
L5OSP
M50 and
MsO SP
M100 s50 55OSP
lcale interval in kg /m3 o-2 | 0.5 1 2 2 1
icale length in mm tt3 t27 725 745 7B 99 87 702 50 62 50 62
Indication Ikg,/ms
Surface
tensonThe values f MC inkg/m3
600 15 o.32 0.28 0.8 0.7 r.2 1.0 2.O 2.O 2.O r.6 1.8 r.6
800 25 0.36 0.32 0.8 o.7 1.4 1.0 2.4 2.O 2.O 7.6 2.O 1.6
1000 35
55
75
o.36 0.32
o.44 0.40
0.48 0.44
0.8 0.7
0.0 0.8
1.0 0.9
1.4 1.0
L.61.2
1.8 1.4
2.4 2.O
2.8 2.4
3.2 2.8
1.0 1.6
2.4 2.O
2.8 2.4
2.2 t.6
1500 35
55
75
o.32 0.28
0.36 0.32
0.40 0.36
o.7 0.6
0.8 0.7
0.9 0.8
2.0 0.8
1.2 t.o
L.4 7.2
3.0 1.6
2.4 2.O
2.8 2.4
4.O 1.2
2.O 1.6
2.4 2.O
2000 55
75
o.32 0.28
0.36 0.32
o.7 0.6
0.8 0.7
0.0 1.0
r.2 t.o
1.0 1.6
2.4 2.O
2.O 1.6
2.41.6
Surface tension in mN/mu
25
Uncertainty Eoaluation in Calibration olHydrometer
For routine calibration of density hydrometers, evaluation
of uncertainty of the measurement results is done as follows,
Uncertainty due to Co,libro.tion Process (Type A)
This urncertainty is due to the calibration process and is
based on the rectangular statistical distribution of the
measurement results and is given by:
uO : u*,/ {3 (1)
where u* is an estimate of minimum variation equal toeither half of the observed variation width or the scale
interval d of the graduations of the hydrometer scale,
whichever is greater.
In the calibration process a hydrometer under test iscalibrated at a given range using two standard hydrometers.
The half of the difference between the two measuremenr
results using two standard hydrometers gives-the value of
u* from which uo is calculated using equation (1) above.
Uncertqinty due to Stondard (Tgpe B)
Uncertainty due to the value of the standard used in the
calibration process is of Type B and is obtained from itcalibration certificate. Suppose Us with coverage factor k:2is the expanded uncertainty of the value of the standard
hydrometer obtained from its calibration certificate then
its standard uncertainty us : Us ,/ k. Thus
uB: us:Us/k
Since the reported value of the hydrometer is the mean
of the two observed values from the two standard
hydrometers, the Type B standard uncertainty due to
standard will be
For routine calibration, contributions in the uncertaintgr fromthe other factors such as corrections due to temperature
or surface tension or the meniscus corrections may be
assumed to be negligible- But for high precisionmeasurements contributions from these factors are taken
into accounl and are estimated as follows,
Stoindo,rd unceftainty due to temperature correction(Type B)
If temperature correction is applicable and it is say TC then
assuming rectangular distribution standard uncertaing due
to temperature correction is given by
urc: TC/bB .....(3)
Standqrd uncertainty due to surface tensioncortection ( Type B)
If surface tension correction is applicable and it is say STCthen assuming rectangular distribution standard uncertainty
due to surface tension correction is given by
rbrc: STC/2.1 3 (4)
Standc,rd uncertainty due to meniscus correction(Type B)
If meniscus correction is applicable and it is, say, MC then
assuming rectangular distribution standard uncertainty due
to meniscus correction is given by
ururc : MC / 2'l 3
Total Type B uncertaing
.(5)
...(6)ue : { [(u,)2 + (ur.)2 + (urr.)' + (u"6)2 I
Colmbined uncertainfg u. : ./ [(rn)2 + (uJz | .....(71
Expanded uncertainty U : k. u" ....... (B)
$rI.
ue : {[( u.r2 + u,22 )/ 4l (21
26
EXAMPLE 7
Calibration of a density hydrometer having same referencetemperature(RT) and surface tension (ST) as that of thestandard hydrometer and liquid employed is also of surfacetension equal to the reference surface tension.
For Hgdrotneter Under Test :
Range : (0.700 to 0.75Q) g/cm3)
Scale interval (d) : 0.000 5 g/cm3
Reference temperature(RT) : 27oC
Surface Tension (fu) : 35 mN/m
For Stond ard Hydrometer
Range o
,(0.700 to 0.750) s/cms)
Scale interval (d) , 0.000 l g/cm3
Reference temperature(RT) : 27oC
Surface Tension (Ts) ' 35 mN/m
Table 2
O bser o ations an d Colc ul o'tions(Unitsin S/cm3)
Ca,lcul ations of U ncerto'inties
Uncertainty due to nreo.surement process ( Tgpe A)
From data taken from the Table 2, uncertainty due to measurement process has been calculated as given in Table 3.
Stando,rdI.D-No.
ObseruedScoIe
P.eading
Correction(From
certificate)
Correctedoalue
Scole pointof the
Under Test
Calculatedcorrection
NIeanCorrection
Rounded
I 2 3 4 6 7 I 9
S1
S2
0.700 22
o.7od rs
- 0.000 12
- 0.000 06
0.700 10
0.70012 0.700
+0.000 10
+0.000 12 .000 11 0.000 1
SI
S2
0.720 t+
0.720 26
+0.000 02
- 0.000 12
0.72016
0.72014 0.720
+0.000 16
0.000 14 0.000 15 0.000 2
S1
S2
0.739 96
0.740 02
+0.000 14
+0.000 06
0.740 l0
0.740 08 o.740
+0.000 10
+0.000 08 0.000 09 0.000 1
S1
S2
o.749.92
o.749.98
+0.000 06
- 0.000 04
o.749.98
0.749 94 0.750
- 0.000 02
- 0.000 06 - 0.000 04 - 0.000 0
27
Table 3Calculation oJ uncertainty due to nreasurement Process (Type A )
(Unitsin g/crn3)
Scale pointsScole CorrectionUsing Standards
Obseroeduaricjion width a*w
uo
(a., /',1 31
SI s2
0.700 +0.000 10 +0.000 12 0.000 02 0.000 5 0.000 29
o.720 +0.000 16 +0.000 14 0.000 02 0.000 5 0.000 29
o.740 +0.000 10 +0.000 08 0.000 02 0.000 5 0.000 29
0.750 - 0.000 02 - 0.000 06 0.000 04 0.000 5 0.000 29
* As observed variation width is less than d value.
a* is taken as d : 0.000 5 g / cm3
Type A standard uncertainty at each point isue:O-OOO29g/"^3
Uncertaintg due to Standsrds ( TVpe B)
The expanded uncertainty of the standards used to calibratethe hydrometer from its calibration certificate is
Us: 0.000 2 g/cm3 with k :2,for each hydrometer.
Standard uncertainty u,l : u,2 : Us / k : O.OOO 2 / 2: 0.000 1 s/cm3
Since the reported value of the hydrometer is the mean ofthe hvo observed values from the two standard hydrometers,the Type B standard uncertainty due to standard will be
u": { (u.12 + u,r2)/4:./t(o.ooo 1)2 + (0.000 Il2l/4: 0.000 O7 g / cm3
Combined uncerto'intg u.:.i(uo2 + uu2 )
: {( o.ooo 29)2 + (o.ooo o7)2 )
: 0.000 3 g/ cm3
Expanded uncertaintV U : k. u. : 2 x O.O0O 3 g/cm3 u:o.ooo6g/cm3
EXAMPLE 2
Calibration of a density hydrometer having differentreference temperature(RT) but same surface tension (ST)
as that of liquid employed Then the certificate correctionand temperature corrections using eq(2) will be needed toapply to the indications of the standard hydrometer.
For Hydrometer Under Test
Range
Scale interval (d)
Reference temperature(RT) : 27 oC
Surface Tension (fu) , 35 mN/m
For St andard Hydrometer
: (0.850 to 0.900) s / cm3l
' 0.0005g/cm3
: (0.850 to 0.900) 9/cm31
' 0.000 1g / cm3
Range
Scale interval (d)
Reference temperature (RT): 20 oC
Surface Tension (Ts) : 35 mN/m
28
Table 4O bser u at ions an d Co.I cul atio n s
(Unitsin S/cm37
Calculqtions of Uncertainty in Measurements
Uncertainty due to measurement process ( Tgpe A)
From data taken from the Table 4 uncertainty due to measurement process has been calculated as given in Table 5.
Table 5Calculation of uncertainty due to measurement Process (Type A )
Stando'rdlD.No.
ObservedScaIe
Reo,ding;Correction
Correctedoalue
Scale pointof the
UnderTest
Calculqtedcorrection
MeanCorr.ection Rounded
7 2 3 4 5 6 7 aS1
s2
0.850 46
0.850 38
CCTCCCTC
0.000 040.000 150.000 080.000 15
o.850 27
0.850 150.850
+O.0O7 27
+0.000 15+ 0.00021 + o.ooo 2
s1'
s2
0.870 24
0.870 58
CC + 0.000 06TC - 0.000 15cc - 0.000 10TC - 0.000 15
0.870 15
0.870 330.870
+0.000 15
+0.000 33+ o.ooo 24 + O.OOO 2
S1
S2
0.890 84
0.890 26
CCTCCCTC
0.000 100.000 150.000 040.000 15
0.890 59
0.890 070.890
+0.000 59
+0.000 07+ 0.000 33 + o.ooo 3
S1
s2
0.900 74
o.900 22
CC + 0.000 08TC - 0.000 15cc - 0.000 04TC - 0.000 15
o.900 67
0.900 030.900
+0.000 67
+0.000 03+ 0.000 35 - o-ooo 4
(Unitsin g/cms)
Scale pointsScale CorrectionUsing Standards
)bserued oolio.tionwidth Q-
UA
1a- /,1 3)SI s2
0.850 +o.ooo 27 +0.000 15 0.000 12 0.000 5 . 0.000 29
0.870 +0.000 15 +0.000 33 0.000 18 0.000 5 . 0.000 29
0.890 +0.000 59 +0-000 07 0.000 52 0.000 5 . 0.000 29
0.900 + 0.000 67 + 0.000 03 0.000 64 0.000 5' 0.000 29: As.half of the observed variation width is less than d value, a* is taken as d : 0.000 5 g / cm3
29
7lF
Standard uncertciinty due to Standards (Type B)
The expanded uncertainty of the standards used to calibratethe hydrometer from its calibration certificate isUs : 0.000 2 g/cm3 with k :2 for each hydrometer.
Sbndard uncertainty u.r:uo:Us/k:0.000 2/2:O.W 7 g/. 3
Since the reported value of the hydrometer is the mean ofthe two observed values from the two standard hydrometers,the standard uncertainty due to standard will be
u,: {[ ( u,r, * u,22 )/ 4 I : ./t{ (0.000 1)2 +( 0.000 7)2 l/4]
: 0.000 07 g/cm3
Standard uncertainty due to temperature correction(Type B)
From the Table 4, the temperature correction is
0'000 75 g/cm3'
Assuming rectangular distribution standard uncertaintv dueto temperature correction is
ut. : 0.000 75 / 2./ 3 :0.000 O4g/ cmz.
Total Type B uncertaintg ue : ./ ( u.2 + ur.2 )
: i/ (0.000 07)2 +( 0.000 04)21 :0.00008g,/ cm3.
Combined uncertainty:
Combined uncertainty u. : { ( uo2 + uu2 )
={ (0.00029)2 + (0.000 0S)21
0.000 30 g/cm3
Expanded uncertainty
The expanded uncertainty U : k.u" : 2 x 0.000 3Oglcm:
Example 3Calibration of a Speific Grauity Hydrometer(I-actorneter) using Density Hydrcmeter as Standard.
The Lactometer having different reference temperature(RT)and surface tension (ST). Then find the mass and diameterof stem of both the hydrometer and calculate surfacetension factor (STF) for each and apply the correctionseparately to the indications of the each hydrometer usingformula STFu (T-Tu) and STFs (T-Ts). But normally T:Tsthen the correction applicable is only to hydrometer undertest.
Also lactometer reading is taken at level liquid surfaceobserving through liquid. But lactometer when used in milkobserved at the level where meniscus meets the stem, someniscus correction is also to be applied to the lactometer.
For Lactometer
Range , (1.000 to 1.040) sp. gr
Scale interval (d) : 0.001 sp-gr
Reference temperatur{Kl), 27 oC
Surface Tension (-fu) ' 50 rnN,/m
STFu lcatcututed from irs mss and Stem Dia.) .. 0.000 O34 s2TsrnS
For Density HydrometerRange , (1.000 to 1.040) g/cms
Scale interval (d) : 0.000 2 g/cm3
Reference temperature(RT): 15 oC
Surface Tension (Is) : 35 mN/m
Assuming T: Ts :35 mN,/m
sp gr.: (Corrected Indicated density/Density of water)(bothdensities are in the same units and at same referencetemperature)
Density of water at 27oC :0.996 5155g,/ cm3
: 0.000 6 g/cm3
30
Table 6Obseroations Sheet
Cqlculqtions of Uncertainty in lvleasurements
Uncertainty due to meqsurement process ( Type A)
From data taken from the Table 6 uncertainty due to measurement process has been calculated as given in Table 7.
Table 7Calculation of uncertainty due to measurement Process (Type A )
* As half of the observed variation width is less than d value, a* is taken as d : 0.001 sp.gr
Standardl.D.No.
ObservedScale
Reading;Correction
Correctedvalue
Scale pointof the
UnderTest
Calculatedcorrection
MeanCorrection Rounded
g/cm3 g/cm3 g/cm3 sp.gr sp.gr sp.gr sp.grS1
S2
0.996 5
0.995 8
CC +0.000 06TC - 0.000 30GC - 0.000 08TC - 0.000 30
0.996 26 g/cm3(0.999 74) sp.gr0.995 42 g/cm3
(0.998 90) sp.gr
1.000sTc - 0.000 51
MG - 0.000 750.998 74
+ 0.00'1 00
+ 0.000 16
+ 0.000 58 + 0.000 6
S1
S2
1.016 2
1.01s 4
CC + 0.000 02TC - 0.000 30cc - 0.000 22TC - 0.000 30
1 .015 92 g/cm3(1.019 47) sp.sr1.015 28 g/cm3
(1.018 83) sp gr
1.020sTc - 0.000 51
MC - 0.000 751-O18 74
+ 0.000 73
+ 0.000 09
+ 0.000 41 + 0.000 4
S1
S2
1.025 8
1.024 6
cc - 0.000 04TG - 0.000 30CC + 0.000 08TC - 0.000 30
1.025 46 glcm3(1.028 64) sp.gr1.024 38 g/cm3
(.027 96) so.qr
1.029 05sTC - 0.000 51
MC - 0.000 751.028 74
- 0.000 10
- 0.000 78- 0.000 44 - 0.000 4
S1
S2
1.036 2
1.035 4
cc - 0.000 06TC - 0.000 30cc - 0.000 12TC - 0.000 30
1.035 84 g/cm3(1.039 46) sp.gr1.034 98 g/cm3
(1.038 60) sp.gr
1.940sTC - 0.000 51
MC - 0.000 751.038 74
+ 0.000 72
- 0.000 14
+ 0.000 29 + 0.000 3
(Units in sp.gr)
Scale pointsScale Comection
Using StondqrdsObseroed oo,riqtion
width Q-
UA
1a- /,,1 3)
SI s2
1.000 +0.001 00 +0.000 16 0.000 84 0.001 . 0.000 58t.o20 +0.000 73 +0.000 09 0.000 64 0.001 . 0.000 58
1.030 - 0.000 10 - 0.000 78 0.000 68 0.001 r 0.000 58
1.040 + o.ooo 72 - 0.000 14 0.000 86 0.001 ' 0.000 58
31
Standard uncertainty due to Standards ( Type B)
The expanded uncertainty of the standards used to calibrate
the hydrometer will be the same as in Example 3 above
i.e. u, : 0.000 07 g / cms
Standard uncertainty due to temperaturecorrection (Type B)
From the Table 6, the temperah-re correction is
{.00030g/crn3
Assuming rectangular distribution standard uncertainty due
to temperature correction is
ut. : 0.000 30 / 2v3 : 0.000 09 g / cm3'
Standard uncertainty due to surface tensioncorrection ( Type B)
From the Table 6, the surface tension correction is-0.0005l g/c z'
Assuming rectangular distribution standard uncertainty due
to surface tension correction is
usrc: 0.000 5l/2./g :o.ooo 15glcms'
Standard uncertainty due to meniscus correction(Type B)
From the Table 6, the meniscus correction is
-0.00075 9/cm3'
Assuming rectangular distribution standard uncertainty due
to meniscus correction is
uMC : 0.000 75 / 2./ s :0.000 22g/ cm3'
Total Type B uncertaintyue={(u.2+u,"2 + urra2 + ut62)
./(o.ooo o7l2 + (0.000 09)2 + (0.000 75)2 + (0.000 22)2 |
0.00029g/cms'
Combined uncertainty:
u.: v(uo2 * ue2) :{t(0.00058)2 + (0.00029)21
0.000 65 g/c z
Expanded uncertainty
= k.u. : 2 x 0.000 65 g/c s
= 0.001 3 g/cm3
CORRIGENDUM
Mr. A. Dasgupta, CMTI - Bangalore contributedsignificantly for the article 'Guidelines for calibration of
Universal Testing Machines, Hardness Testing Machines
& Impact testing machines' published in NABL NEWS,
Issue No. 39, July 2OO5- His name was omitted as an
oversight. The error is deeply regretted.
i
Schedule for implementation ofISO/ IEC 17025: 2OO5
ii)
Receipt of application as per ISO,/ IEC 17025.
2005 from June 29. 2005. Any application and
Quality Manual received after this date as per
earlier standard is to be revised by the laboratory
to conform to the new standard.
All assessments to take place on the basis of ISO/IEC 17025:2005 from Januarv 0t. 2006.
All accredited/ applicant laboratories under going
assessment after January 01, 2006 to submit
revised Quality Manual as per ISO/ IEC 17025
2005 (if required) atleast one month before the
date of assessment.
iii)
32
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identification & volumefraction
Subodh Technologists, 30.10.2005Mumbai
Nodc,l labratory Last DateforRegistration
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4 Dec 05-09, 2005 Laboratory Quality System Management andInternal Audit Course
ERTL. Mumbai
5. Dec 06-08, 2005 Length Calibration NPL. New Delhi
6. Jan- 2OO6 (3 days) Pressure and Vacuum Calibration NPL, New Delhi
7. Jan. 30 -Feb. 3, 2006 NABL Assessor Course NITS, BIS, Noida
8. Feb. 13 - L6,2006 Laboratory Quality System Management andInternal Audit Course
NITS, BIS, Noida
34
Conto.ct Details:For Training Courses on Laboratory Quality System Management and Internal Audit Course. the details are as under,
I{ITS, BIS, Noidol EKIUltrl), Mutnbai CETE, Bo,ngaloreC-ontqctAddress
Electronics Regional TestLaboratory (West),Plot No. F -7 & 8, MIDC Area,Opp. SEEPZ, Andheri (East),Mumbai - 400 093
Tel: O22-28301 138, 28307468Fax:O22-282257L3
National Institute ofTraining for Standardization(NITS), Bureau of Indian Standards,A - 2O-2t,lnstitutional Area,Sector - 62, Noida - 2Ol3O7
Tel: O72O-24O22O2 - 07Fax:Ol2O-24O22O2-O3
Center for Electronics TestEngineering, ETDC,100 Feet Road,Peenya Industrial Estate,Bangalore- 560058
Tel. O8O-227 24232, 28393577F axO8O-227 24232. 2839 3520
ContorctPercon
Mr. P. K. Srivastava,Addl. Director
Mr. Anupam Kaul,Head (Trg)
Mrs. Veena. S. Kamath.Director
Po;2mentMode
Through Demand Draftfavouring PAO-DIT payableat New Delhi
Through demand draftfavouring NITS, BIS, Noida
Through demand draft favouringPAO-DI payable at Bangalore
For other cour,'ses, please conto,ct:
NIn M.VN- Moho'n,National Accreditation Board for Testing & CalibrationLaboratories,B-4 Apartment, Qutab Hotel,New Mehrauli Road, New Delhi - 110016Phone: O77- 265297L8- 20,26526864Fax, 011- 265297 L6, E-mail : [email protected]
NABL is cunently looking for uperts in the followingareas to trqin os NABLAssessors..
, Density,Vacuum,
Testing Lqboro,tories: Pesticides, Microbiology, Drugs,pharmaceuticals, Building materials, Pollution -&environmental, Food, Explosives, Ores and minerals, Metals,Fertilizers, Gold assaying, Forensic science and NDT.
Clinical (Medical)Cytopathology, HistBiochemistry and Cytoge
Experts must be experienced in both the management andoperation of testing & calibration laboratories and betechniqally knowledgeable in onb or more areas of testing
and calibration. The criteria for the selection of experts tobe trained as assessors are as follows :
1. Educational qualification:o For testing and calibration laboratories: post
ce or Graduate in Engineering within Testing,/ Calibration laboratory
o For Clinical Laboratories: MD with 5 yearsexperience in clinical laboratory.
2- Should be currently working in the laboratory.3. Should have good communication skills.
Interested candidates may send their bio-data with thedetails of qualification, experience, current employer, fieldof testing / calibration, group of tests or calibratlon withhands on experience, to:
Mn M.VN. Nloho,n,National Accreditation Board forTesting & Calibration Laboratories,B-4, Aparhnent, Qutab HotelNew Mehrauli Road, New Delhi - 110016Phone: O7l- 26529718- 20,26526864Fax: 011- 265297 L6 E-mail : [email protected](For updated informo,tion on schedules of NABLtraining courses, you are requested to uisit NABLue,bs ite.: www. no,bl-indio'. org)
35
TestingS. No.1_
2.
3.4.5.6.
t.8.9.10.
11.t2.13.74.15.L6.L7.18.19.20.27.
22.23.24.25.26.27.28.29.30.31.32.33.34.35.
NEW ACCREDITATION GRANTED(JULY - SEPTEMBER, 2OO5)
LaborstoriesI-o,boroltoryNo'meAglow Quality Control Laboratory Pvt. Limited, KolkataAquadiagnostics Water Research & Technology Centre, BangaloreBhagavathi Ana Labs Limited, HyderabadCentral Forensic Science Laboratory, ChandigarhCentral Institute of Hand Tools, JalandharCentral Materials and Processes Laboratory, Foundry & Forge Division,HAL (Bangalore Complex), BangaloreCTR Electronics Test Laboratory, AurangabadElectronics Test & Development Centre, ChennaiHindustan Coca-Cola Beverages Pvt. Ltd, AmeenpurIndependent Testing Laboratories, National Council Tor Cement &Building Materials, HyderabadLaboratory of Government Examiner of Questioned Documents, Hyderabad
Laboratory Services Division, Sargam Metals Private Ltd., ChennaiManisha Analytical Laboratories Private Limited, MumbaiMetal Testing Centre, ChennaiMetallurgical Laboratory, Heavy Vehicles Factory, Avadi, ChennaiMicro Engineering and Testing Laboratory, Rai, SonepatNetwork Clothing Company (P) Limited - Testing Services (NTS), TirupurPhysiChem Material Testing Laboratory, NashikPollution and Project Consultants, Kolkata
Quality Assurance Laboratory, GAIL (lndia) Limited, Lakwa
Quality Assurance Laboratory, Raymond Limited -Denim Division, Yavatmal (Maharashtra)
Quality Control Department, Kochi Refineries Limited, Ambalamugal, Kerala
Quality Control Laboratories, Birla Cement Works, Chittorgarh (Rajasthan)
Quality Control Laboratories, Chanderia Cement Works, Chittorgarh (Rajasthan)
Quality Control Laboratory for Processed Foods, Ludhiana
Quality Control Laboratory, UltraTech Cement Limited. A.P. Cement Works, Tadipatri
Regional Laboratory, Textile Committee, LudhianaReliable Testing Services, MumbaiScientific Services, Tata Steel Limited, JamshedpurSGS India Private Limited, OG & C Laboratory, ThaneSoil Engineering and Material Testing Wing, Pune
Standard (Madras) Laboratories, ChennaiSwitchgear Testing Laboratories (STL), Larsen & Toubro Limited, Powai, Mumbai
Testings Concern, HowrahVXL eTech - EMClSafety Lab, Bangalore
DisciplinesC,MC,B
C,M,BF
M
C, M, NDTLE
C,B
C,MF
MC,B
MC,M
MC,M
MCC
C,MC
C,MC,M
CC,MC,MC,MC,M
CC,MC,M
E
C,ML
36
Calibrotion Lsb oratories1. Accurate Engineering Co. Pvt- Ltd., Gurgaon2. Caliber Gauges & Instrument Laboratory, pune3. Central Institute of Hand Tools Laboratory, Jalandhar4. central Materials and Processes Laboratory, Foundry & Forge Division,
HAL (Bangalore Complex), Bangalore5. Dimensions, Bangalore6. ICL Certifications Limited, (Calibration Division), panchkula7- Mikronix Gauges Pvt. Ltd., Aurangabad8. Quality Solutions (lndia), Faridabad9. Shriram Institute for Industrial Research, Bangalore10. Shriram Institute for Industrial Research, New Delhi11. Sankalp Hi-Tech Corporation, Nashik72. Tespa Calibration Services, Bangalore
Clinical Laboratories
MMM
MMMMMM
FF
MM
Immunology, Microbiology and
3
4.
5.
6.
1. Bhide Laboratory, Mumbai
2. Department of Laboratory Services,B.M. Birla Heart Research Centre, KolkataDepartment of Pathology, CalcuttaMedical Research Institute, KolkattaDr. Vaidya's Laboratory, ThaneDr. Ajay Shah Pathology Laboratory,MumbaiLaboratory Services of IndraprasthaApollo Hospital, New Delhi
7. Manipal Hospital Diagnostic Services,Bangalore
8. MolecularDiagnosticLaboratory,Reliance Life Sciences, Maumbai
9. Madras Diagnostic Centre, Chennai10. Sipra Labs Limited (Clinical Laboratory),
Hyderabad11. Testing & Cross-Match Laboratories,
Prathama Blood Centre. Ahmedabad
Biochemistry, Pathology, Haematology,SerologyBiochemistry, Pathology, Histopathology
Biochemistry, Pathology, Cytopathology, Haematology,Histopathology, Microbiology and SerologyBiochemistry, Pathology, Haematology, SerologyBiochemistry, Pathology, Haematology
Biochemistry, Pathology, Haematology, Cytopathology,Histopathology, Microbiology and SerologyBiochemistry, Pathology, Haematology, Cytopathology,Histopathology, Microbiology and SerologyCytogenetics, Immunology
Biochemistry, Pathology, Haematology, Microbiology and SerologyBiochemistry, Pathology, Haematology, Immunology
Immunology
Abbteoiationsused:C:Chemical,M=Mechanical,E:Electrical,T:Thermal,B:Biological,FF:FluidFlow,P:Photometry,L:Electronics,F:ForensicTesting,NDT:NonDestructiveTesting,R:Radiological,ET:Electrotechnical,O = Optical, T&O - Thermal & Optical
Scope of Accreditation and other detoils of all Accredited Lo,[p1r61tories are auailable on NABL web site" ww w. n abl-i n di a. org" u nder' Labo rato ry Se qrc h,.
37
7
MASTER LIST OF(NABL 2OO,
All NABL documents can be downloaded free
NABL DOCUMENTSIssue No. O8)
of cost from NABL website : www.nabl-india.org
S. No. Document Name Doc. No. lssue
No.
lssue
Date
Last Amend.
No.
Date of last
Amend.
Price
(Rs.)
'| General Information Brocnure NABL 1OO Dec. 2004 Free of cost
2. Specific Criteria for Biological Testing Laboratories NABL 102 01 1 994 o2 21.10.03 Free of cos
a Specific Guidelines for Chemical Testing Laboratories NABL '| 03 02 28.02.o3 01 05 o7 05 Free of cos
4. Specific Criteria for Electrical Testinq Laboratories NABL 1 04 o2 02.04.03 01 05 07.05 Free of cosl
tr Specific Criteria for Electronics Testing Laboratories NABL 105 0'1 1 995 o2 05.07.05 Free ol cost
6 Specific Criteria for Fluid Flow Testing Laboratories NABL .I 06 0.t 1 994 02 05.07.05 Free of cos
7. Guidelines and Specific Criteria for Accreditation
of Mechanical Testing Laboratories
NABL 107 02 Nov. 1999 o2 05.07.05 Free of cost
B Specific Criteria for Non-Destructive Testino
Laboratories
NABL 108 01 1 994 o2 05.07.05 Free of cost
Specific Criteria for Photometry Testing Laboratories NABL 109 01 April 1998 02 05.07.05 Free of cosl
'10 Specific Criteria for Radiological Testing Laboratories NABL 110 01 1 994 02 05.07.05 Free of cost
11 Specific Criteria for Accreditation of Medical Laborator TSNABL 112 o2 11 05.05 o2 05.07.05 Free of cost
12 Specific Guidelines for Accreditation of Forensic
Science Laboratories & Checklist for Assessors
NABL 113 01 18 06.98 02 05.07.05 Free of cosl
13. Specific Guidelines for Accreditation of DNA
Fingerprinting Laboratories & Checklist for Assessor
NABL 113A 01 29.'t2.99 o2 21.10 03
Reinducted
Free of cost
on reqquest
14 NABL Guidelines for Food Testing Laboratories NABL 1.14 02 05.07.05 00 Free of cost
Specific Criteria for Calibration Laboratories in
Electro-Technical Discipline
NABL-12.I 03 08.10.02 01 05.07.05 Free of Cost
16. Specific Criteria for Calibration Laboratoiies in
Mechanical Measurement Discipline
NABL 122 03 08. t 0.02 01 05.07.05 ree of Cost
rl
I
;i
lir::.::::
if-_
38
A{
S. No. Document Name Doc. No. lssue
No.
lssue
Date
Last Amend.
No.
Date of last
Amend.
Price
(Rs.)
17 Specific Criteria for Calibration Laboratories in
Radiological Discipline
NABL,I23 03 08 10.02 0'r 05.07.05 Free of Cos
18 Specific Criteria for Calibration Laboratories in
Thermal & Optical Discipline
NABL 124 03 08.10.02 02 05.07.05 Free of Cos
19 .Specific Criteria for Calibration Laboratories in
Fluid Flow Discipline
NABL ,I 25 03 08.10.02 01 05.07.05 Free of Cosl
zu Specific Criteria for Site Testing and Site
Calibration Laboratories
NABL 130 02 13 08.02 01 05.07 05 Free of Cos
)4 Terms and Conditions for Maintaining NABL
Accreditation
NABL 131 o4 01 .o3.o2 02 05.07.05 Free of Cos'
22. NABL Guidelines to Accredited Laboratories
for use of NABL Logo
NABL 133 02 13.07.00 02 13.08.02 Free of cosl
)? Guidelines for Estimation & Expression
of Uncertainty in Measurement
NABL 14,I 02 o2.o4 00 03 18.08.00 Free of Cos
24 Policy on Calibration and Traceabilitv NABL 't42 03 't8.'to.o4 o2 05.07.05 Free of Coslof Measurements
25. Application Form for Testing Laboratories NABL 151 09 14.03.05 02 05.07.05 Free of Cos
26 Application Form for Calibration Laboratories NABL 152 09 14.03.05 o2 05.07.05 Free of Cosl
27 Guide for preparing a Quality Manual NABL 160 03 05.07 05 00 Free of Cos
28 Guide for Internal Audit and Management Review
for Laboratories
NABL 161 02 02.o4.o2 02 05.07.05 Free of Cos
Guidelines for Proficiency testing programme
for Testing & Calibration Laboratories
NABL 162 03 04.04.01 01 05.07.05 Free of Cosl
30 Policies & Procedures for Interlaboratory
comparisons and/ or Proficiency Testing
NABL 163 o4 13.08.02 o4 18.10.04 Free of cosi
'39
S. No. Document Name Doc. No. lssue
No.
lssue
Date
Last Amend.
No.
Date of lasl
Amend.
Price
(Rs.)
31 Guidelines for Inter-Laboratory Comparison forCalibration Laboratories where formal PT
programmes are not available.
NABL 164 01 28.04.05 00 Free of cosl
32. Sample Calculations for Uncertainty ol
Measurement in Electrical Testino
NABL 174 o2 14.10.O4 01 05.07.05 Free of Cos
JJ Master list of NABL Documents NABL 2OO 08 0s.07.05 00 Free of cos
34. Pre-Assessment Guidelines and Forms NABL 209 01 02.12.O2 0t 05 o7 05 Free of cost
35 NABL Assessor Guide NABL 210 03 01.05.02 03 05 o1 05 Fi re of cosl
JO Policy and Procedures for Assessment,
Surveillance & Re-Assessment of Laboratories
NABL 214 03 03.o4.o2 05 05.07.05 Free of cosl
37 Assessment Forms & Checklists
(Based on ISO/IEC 17025)
NABL 215 UJ 0s.07.05 00 Free of cost
38 Policies 8. Procedures f or Dealino with
Adverse Decisions
NABL 216 01 28 10.O2 10 05,07 05 f:ree of cos
39 Bio-data of Assessors NABL 22-I 01 02.08 04 00 05 07.05 ['ree of cos
Note :
1. The shaded boxes of a row indicate the new issues or neu/ amendments of the document and the shadedrow indicate the new documents published or withdrawn.
2. All NABL documents can be downloaded free of cost f rm NABL website : www.nabl-india.org
3. The Master list is updated on a reqular basis and is also availaille on NABL wbsite.
ECitorial Board : Shobhna Sharma - Chief EditorRajesh Maheshwari - MemberR. Srikanth - Member
National AccreditationB-4
tiABL NEWS is quarterly published by
Board for Testing and Calibration Labc'-ai,,.-'iies (NABL)
Apartment, Qutab Hotel, New Mehrauli Road,New Delhi - 110016. India
Tel.: 011- 26529778- 20,26526864, Fax: 017- 26529776E-rrail, [email protected] Website : www.nabl-india.org
Registered Office:Technology Bhavan,
Department of Science & Technology,New Mehrauli Road. New Delhi-110016
40