basic concept of measurement

8/17/2019 Basic Concept of Measurement

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CONCEPTS OF METROLOGY AND IMPORTANCE OFCALIBRATION

Nihal Gunasekara

Sri Lanka

Bangladesh BESTProgramme


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KEY WORDS

CALIBRATION – Comparison

METROLOGY – Science of Measurement

TRACEABILITY – Unbroen C!ain of Comparisons

UNCERTAINTITY – Error in Measurement

ACCRE"ITATION – T!ir# $art% Ascertain

CALIBRATION INTER&AL – E'uipment Remains Re(iab(e



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WHAT IS METROLOGY

SCIENCE OF MEASUREMENTS

Everything hasto do with

measurement

"esi)nin)

Con#uctin)

Ana(%*in) Resu(ts

E+periment

or test

,it!in t!e Metro(o)% rea(m

Allowing people

to plan their lives

and makecommercial

exchange with

confidence

CAN BE SEENEVERYWHERE



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METROLOGY

Metro(o)% Co-ers T!ree Main Tass.

T!e #efinition of internationa((% accepte# units of measurement

T!e rea(i*ation of units of measurement b% scientific met!o#

Estab(is!ment of traceabi(it% c!ain in #ocumentin) t!e accurac%

of a measurement

/ Metrology is essential in scientifc

research”



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CATEGORES O! METROLOGY Scientifc Metrology – "e-e(opment of measurement

stan#ar#s

Industrial Metrology – To ensure the adequate

unctioning of measurement

instruments use# in in#ustr%0

pro#uction 1 testin)

(aboratories

Legal Metrology or

Weights & Measures – Accurac% of measurement

,!ere t!ese !a-e inf(uence on t!e



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AREAS O! "D#STRAL METROLOGY

Mechanical Metrology – Rea(ises 0 maintains an#

#isseminates t!e nationa( measurement stan#ar#s in t!e areas of

Mass0 &o(ume0 $ressure an# "imension

Electrical Metrology –– Rea(ises 0 maintains an#

#isseminates t!e nationa( measurement stan#ar#s in t!e areas of

AC2"C0 (o, fre'uenc%0 time 1 fre'uenc% an# temperature



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LEGAL METROLOGY

Ser-ices offere# b% (e)a( metro(o)% are.

Mass measurements verifcation. -erification of a((

mass measurin) instruments 3ba(ances0 tra#e masses etc45

olume measuring instruments . -erification of fue(

#ispensers0 taners 0 meters etc4

!re"ac#aging control .-erification of 'uantities in

prepaca)e# pro#ucts 3mass0 -o(ume0 (en)t!0 number etc45



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Ca$i%ration &O$d De'inition(

$ %aliration is the com"aring o anun#no'n measurement device against

equal or etter #no'n standard unders"ecifed conditions”



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alibration

$ Operation that, under specifed conditions, in a frst step,

establishes a relation between the quantity values withmeasurement uncertainties provided by measurementstandards and corresponding indications with associatedmeasurement uncertainties, and in a second step, uses thisinormation to establish a relation or obtaining a measurement

result rom an indication ” International Vocabulary of Metrology )( )%*M +,,-+,.+ – International ocaulary o Metrology /



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#nits o' Measurement

SI Units published by BIPM Bureau of 6ei)!ts an# Measures!

)ase #nits*

+uantity #nit Sym%o$

"ength metre m

Mass kilogram kg#ime second s

#emperature kelvin $

%lectric current ampere A

"uminous intensity candela cdAmount of substance mole mol



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Metrology Laboratorie ,rimary La%oratories "ML- "M- ",L et.

Re'eren.e La%oratories

Ca$i%ration La%oratories



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Mea!re"ent #n$ertainty

“ non-negative parameter characterizing the dispersionof t!e 'uantit% -a(ues being attributed to a measuran#0

based on the information used”

It arises due to t!e imperfections in t!e measurement

s%stem

No measurement s%stem is perfect 77777



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#n$ertainty

An estimate of t!e possib(e error in a measurement

Ty/e A eva$uation

A series of repeate# obser-ations is obtaine# to #etermine

t!e stan#ar# #e-iation of t!e measurement resu(t .

Ty/e ) eva$uation

T!e e-a(uation is carrie# out usin) a-ai(ab(e information

foun# in ca(ibration reports0 certificates0 specifications etc&



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E%&an'e' #n$ertainty

Calculate combined standard uncertainties

Type

Type !

"#p$ %nc$ % & Combined %ncertainty ' Co(era)e *actor



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I(i)a*a 'iagra"

%ncertainty

o* an o(en

Calibration ,!-

Test o(en

.esolution ,!-

C/C ,!-

Scatter ,-

i)ital

Thermometer .esolution ,!-

.e*erence TC

Bangladesh BEST Programme


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on+i'en$e Le,el

Gaussian probability distribution

k 5k86 7ithin 1 o* mean

+6 7ithin 2 o* mean

6 7ithin 3 o* mean



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Metrologi$al Tra$eability

”property o a measurement resultwhereby the result can be related to areerence through a documented unbroken

chain o calirations, each contributing to themeasurement uncertainty ”

or or

/ / H! " #$%&'# "H(" H! " #$%&'# "H(" T6O MEASUREMENTST6O MEASUREMENTS "H# %(M# "H# %(M#

*&($"I"I#% ('#*&($"I"I#% ('# COM$ATIBLE COM$ATIBLE ””



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1818

:o; o 7e Get Traceability <

Common point o* re*erence

My laboratory Your laboratory Their laboratory



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11

"M0 The Lin1 Organisation to the nternationa$ Arena

nternationa$ standards

"ationa$ .ommunity that is using

measurements

"ationa$ Metro$ogy nstitute


2ERAC2Y O! MEAS#REME"T STA"DARDS


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2ERAC2Y O! MEAS#REME"T STA"DARDS

nstruments

#sed in La%3

ndustry

Wor1ing

Standards

Se.ondary

Standards

,rimary Standards

Tra.ea%$e to ),M


HIERARCHY OF

MEASUREMENTS


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21

=etal *i#edpoint

Number Substances Statee*inin) temperature

> oC

1

23

4

+

9

8

:)

:20

Ga

?n

Sn

@n

l

)

u

Cu

T

T

=A

A

A

A

A

A

A

234$31+

293$1

302$1442$948+

+0+$098

2$99

33$493

1234$3

1339$33

13+9$99

38$8344

0$01

2$941+$+8+

231$28

41$+29

0$323

1$98

104$18

1084$2



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22

CL?!.T?BN :?"..C: BA =SS STN.S

),M Ki$ogram

"ationa$ Ki$ogram

C$ass E4- E5-!4- !5Masses

Ana$yti.a$ 6To/ $oading

,re.ision

)a$an.es

OML M4-M5-M7

Masses

OML R89

Masses

TRADE

MASSES

,$at'orm 6 To/

$oading %a$an.es

Weighing

)ridges



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2323

!?D= Drototype 1k)

E-AMPLE

MASS COMPARATOR

Drototype 1k)

Calibrate

Traceable to

nalytical !alance

Trans*er

%S"

Set o* Classes "2E A1E A2E and =1

Traceale !o

SI Un"!s


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24

GA#GE BLOC. COMPARATOR

Drimary Standard

Laser inter*erometer

Traceable to

Grade > set

Grade 1 set

%S"

Compare

Calibrate



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2+

E%a"&le

/0 Per+or"an$e Tet on a In$!bator at 12 3

402

o

Set Temp$

oC

?ndicator Falue

oC

=easured =ean (alue

oC

"#panded%ncertainty

oC

=in =a# NearSensor

%pper =iddle Lo;er

34$+ 34$+ 34$ 34$ 34$9 34$+ 34$2

0$2



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2

50 Per+or"an$e Tet on a Water Bat( at 24

o

S

,

C

R

+

Set Temp$

oC

?ndicator Falue

oC

=easurement

Locations

=easured=eanFalue

"#panded%ncertainty

oC=in =a#

48$0 4$+ +0$0 C

D

.S

+0$1

+0$2

+0$1

+0$1+0$0

1

#ni'ormity 0 :;


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29

COM,ARATOR )ALA"CES

CLASS E4 4 1g

CLASS E4 SET

CLASS E5 SET

CLASS !4 SET

CLASS !5 SET

CLASS M4 SET

MASS

Re'eren.e and Au=i$iary E>ui/ment



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28

CAL)RATO" "TER?ALS

6!at is Ca(ibration inter-a( 888

,eriod o' time o' use to ensure the e>ui/ment remains re$ia%$e

nterva$ is too short 0 Ca$i%ration @@@@@

nterva$ too $ong 0 Ris1 o' %ad measurements



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2

CAL)RATO" "TER?ALS

ISO 9:;


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RECOMME"DED CAL)RATO" "TER?ALS

" "o sing$e .orre.t answer Ca$i%ration re/resents an

instantaneous sna/shot o' a.tua$

.ondition

De/end u/on

Leve$ o' stress su%Be.tedSta%i$ity o' /ast .a$i%rationA$$owa%$e to$eran.e range

Re>uired a..ura.y+ua$ity Assuran.e Re>uirements



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RECOMME"DED CAL)RATO" "TER?ALS

!ina$ Ana$ysis ,eriod %etween two .a$i%rations

Determined 6 Monitored

#SER 2MSEL!



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2OW TO ESTA)LS2 CAL)RATO" "TER?AL

Consider in'$uen.ing 'a.tors and e=isting 1now$edge 0 eg

Accurac% sou)!t 1 conse'uences of error Manufacture>s recommen#ations Accommo#ation 1 en-ironment $urpose an# usa)e Maintenance 1 ser-icin) Tren#s from pre-ious ca(ibration?re'uenc% of c!ecs

Etc4 etc4 etc4 @4

Re'; LAC G 58 0 Guide$ines 'or determination o' .a$i%ration interva$ o'

measuring instruments


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3333

RECOMME"DED ,RACTCES Ca$i%ration at &/$anned( /eriodi. interva$s to

ensure a..e/ta%$e a..ura.y 6 re$ia%i$ity

Shorten the interva$s when resu$ts o' /revious

.a$i%ration suggest it

May $engthen interva$s on %asis o' demonstrated

/er'orman.e

Do.umented /ro.edure 'or assigning and adBusting

.a$i%ration interva$s

!u$$y do.umented re.a$i%ration system



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34

ALIBRATION OF 6OL#METRI GLASSWARE

FLAS.S

YLINDERS

B#RETTES

PIPETTES

A #RA Y LASSES

LASS A 7 Hig(er

gra'e

LASS B 7 Lo*er

gra'e



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3+

E%a"&le 8 Pi&ette

Nominalcapacity,ml-

Limit o* "rror ,ml-Class Class !

1

2+

100

200

0$008

0$03

0$08

0$1

0$01+

0$0

0$1+

0$2

METHOD

#ra$"me!r"c Me!hod % IS& '()( *+&,&-.aora!or/ #lass0are* Vol1me!r"c "ns!r1men!s*Me!hod o2 Tes!"ng o2 ca3ac"!/ and 2or 1se4



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3

IN8HO#SE PERFORMAN E HE .S

(During Calibration Interval)

ANA.YTICA. BA.ANCES % Using a CalibratedWeight

INCUBATORS * Using a CalibratedThermocouple

#.ASS THERMOMETERS* ce !oint



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?mportance o* Calibration

Assuran.e o' a..urate o' measurements A%i$ity to tra.e measurements to nternationa$

standards

nternationa$ a..e/tan.e o' test3.a$i%ration re/orts

Corre.t diagnosis o' i$$ness &medi.a$ re/orts(

Consumer /rote.tion &$ega$ metro$ogy(

Meeting the re>uirements o' SO ::: and 49:5



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Te$(ni$al Co"&eten$e o+

Calibration Laboratorie

9

Mea!re"ent are

tra$eable to SI #nit

Ho* *e en!re

A REDITATI N



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De+ine' riteria +or Laboratory A$$re'itation

Metrology Laboratory

• Br)aniHation• Laboratory uality System

• uali*ied personnel

• .an)e o* the ;ork capabilities and test methods

• Laboratory practices and mana)ement system

• .eliable standards and measurin) de(ices

• Laboratory *acilities

• deIuate measurin) capabilities

• Traceability maintenance

• Calibration records

• Satis*actory completion o* internal audits



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:#ALITY SYSTEM ISO;IE /


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4141

A REDITED LABORATORY

IMPLEMENTATION OF ISO /


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4242

"NF?.BN="NTL CBN?T?BNS

T"=D".T%."

:%=??T

?. F"LBC?T

A."" BA F?!.T?BN

?LL%=?NNC"



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A REDITED

MASS LABORATORY

EN6IRONMENTAL CONDITIONS= TEMPERAT#RE= 51 > 402 4C ? H#MIDITY = 24 >/4@



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4444

CC."?T" T"=D".T%." L!B.TB.

E"?RO"ME"TAL CO"DTO"S0 TEM,ERAT#RE0 57 F4 :C - 2#MDTY 0 : F4:



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CBNT"NTS BA CL?!.T?BN C".T?A?CT" NAME AND ADDRESS : CU"TO#$%& '()O%(TO%*

METHOD

CONDITION RECEIVED

IDENTIFICATION DATE OF CALIRATION

60TE 78 2E%0LI920TI71 :

CALIRATION RES!LTS

!NCERTAINT" OF MEAS!REMENT

TRACEAILIT"

ENVIRONMENTAL CONDITION



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RANGE 0M0

# ONE MAR7 PIPETTE & !o +&&

&8&,

##RA6UATE6 PIPETTE & !o +9 &8&&,

#BURETTE & !o +&&

&8&,

# VO.UMETRIC F.AS7 & !o +&&&

&8&,

##RA6UATE6 MEASURIN# CY.IN6ER & !o +&&& &8&,

SAMPLE OFS OPE OF A REDITATION

CA.IBRATION

$L$L


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48

A..redited Metro$ogy

!a.i$ities

ndustries

Prod1c!s

Be!!er Place"n #loalMar:e!

51al"!/."2e

Techn"cal Com3e!enc/

ISO Cer!";ed 5MS

TracealeMeas1remen!s

Ens1re


B l d h BEST


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$%aliration olaoratoryequi"ment isim"ortant to otain

reliale testresults”


basic concept of measurement

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