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

PRO F I CI EN CY TE'STIN G P ROG RAM ME S

Two new Proficiency Testing programmes in the Chemical and Mechanical disciplines for the testing laboratorieswill start very soon- The participation in NABL PT programme is mandatory if the area is covered in the laboratory'sscope of accreditation- The participation fee for each programme is Rs. 2,5OO/-. The accredited and applicantlaboratories may register their name for participation in the relevant programme by sending participation fee in theform of DD in favour of NABL, New Delhi.

Ptogranntne Progrannme Porrimeterccode n(nne

TM lE MetallographicTesting of Steel (Group A, B, C, D

Thin & Thick Series)

identification & volumefraction

Subodh Technologists, 30.10.2005Mumbai

Nodc,l labratory Last DateforRegistration

TC39 Testing ofSkimmed MilkPowder

The request for participation in the above programme rnantioning the ptogramx7,e code number and enclosingDD fot the requisite o,mount may be forwarded lortest by the date as giuen aboue-

Five more proficiency testing programmes on Electrical and Electronics testing which were launched earlier are stillopen for participation. The interested laboratories may participate in these programmes. Please refer to ourwebsite www.nabl-india.org for details-

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i-

NABL TRAINING ACTIVITIES

tbDag Training Course on "I-o,botatory Quality Sysfem Nlanagetnent o,nd Internal Audit"Designed for laboratory personnel involved in the management and establishment of laboratory quality systems, andestablish/manage an internal audit programme for their laboratories as required by NABL criteria & International StandardrsolEc 17025.

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Training ScheduleS. No. *hedule Coutse Venue

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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 : training@nabl-india.org

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 : training@nabl-india.org(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, info@nabl-india.org Website : www.nabl-india.org

Registered Office:Technology Bhavan,

Department of Science & Technology,New Mehrauli Road. New Delhi-110016

40