-
been granted such certificates, may be found on the OIMLweb site
and information is also published in theAssessment of OIML
Activities (see page 43).
However, major improvements still have to be madeover the next
few years, in particular:
K To simplify the certification of families of
measuringinstruments, i.e. instruments from the same manu-facturer,
based on the same technology and differing onlyin certain
characteristics (e.g. the maximum capacity) inwhich case it is not
necessary to repeat all the tests on allthe instruments belonging
to the family.
K To develop the certification of modules, e.g.
indicatingdevices, sensors and electronic equipment, with a view
tofacilitating the certification of an instrument made up
ofcertified modules.
K To develop the certification (in fact the initial
verifica-tion) of mass-produced instruments, since up to now
theOIML Certificate System applies to types (patterns)
ofinstruments.
K Above all, the objective is to develop multilateral
agree-ments of recognition of test results associated with
OIMLcertificates in order to eliminate multiple testings andthus
apply the WTO directives concerning testing in thelegal metrology
field.
This is the responsibility of the OIML TechnicalSubcommittee TC
3/SC 5 under a joint USA/BIML secre-tariat and significant progress
in this field is expected to bemade by the end of 2002. This
activity is conducted takingdue consideration of the views of
certification bodies as wellas those of manufacturers of measuring
instruments, and inline with the general principles on conformity
assessment,testing and accreditation developed within the
WTO,ISO/CASCO, ILAC and IAF. K
Launched in 1991 following several years of reflectionwithin the
OIML culminating in a decision made bythe International Committee
of Legal Metrology, theOIML Certificate System for Measuring
Instruments is nowten years old.
Initial developments were very slow and in fact the
firstcertificate was not issued until 1992. Over the following
twoyears, the number of certificates issued only just exceeded20
(in 1993) and 40 (in 1994). However from 1995 on therewas a
significant acceleration and one decade later thenumber of
certificates issued annually now exceeds 100, asmay be seen from
the bar chart on the front cover of thisBulletin.
A number of other key figures also illustrate the growingsuccess
of this activity:
K Some 20 OIML Member States (out of 57) have nowestablished
national authorities for issuing OIMLcertificates, and a number of
other Member States areconsidering doing likewise.
K More than 30 categories of measuring instruments(weighing
devices, fuel dispensers, clinical thermo-meters, breath analyzers,
etc.), may receive OIMLcertificates and this number is
progressively increasingwith the issuing of new or revised
Recommendationsapplicable within the System.
K Over 200 manufacturers or importers of measuringinstruments
from some 30 countries have successfullyapplied for OIML
certificates.
K More and more countries accept OIML certificates andassociated
test results to accelerate and facilitate thegranting of national
or regional type approvals.
More detailed statistics concerning certificates
issued,including information on those manufacturers that have
K Editorial
Ten Years of OIML Certification
BIML
-
Abstract
For a given error distribution, confidence in the measure-ment
process depends on the test uncertainty ratio (TUR)and on the
confidence interval. When selecting ameasuring instrument or
measurement standard to carryout a calibration or verification or,
in general, a meas-urement, this dependence becomes a vital
issue.
The author has considered the effect of several TURsencountered
in practical situations on incorrect testdecisions. This
consideration has also been extended tothe effect on correct test
decisions, reliability of test resultsand confidence in the
measurement process for normalerror distribution, for both the
equipment under test(EUT) and the calibrating instrument, at two
confidenceinterval specifications.
This paper contains a short presentation of specificrelevant
definitions and issues, results of the study anddiscussion, and two
examples of a lack of specificinformation on the TUR in certain
standards. The analysishas been performed for TURs ranging from 1:1
to 100:1and for confidence interval specifications of 2s and 3s
.
Both the information given and the conclusions whichhave been
drawn can be used in calibration and verifica-tion and, generally,
also in measurement.
1 Introduction
Measurements and the calibration of measuring instru-ments are
essential aspects of activities such asmaintaining quality control
and quality assurance inproduction, complying with and enforcing
laws and
regulations, conducting research and development inscience and
engineering and calibrating and verifyingmeasurement standards and
instruments in order toachieve traceability to national
standards.
Calibration is the determination, by measurementand comparison
with a measurement standard, of thecorrect value of a reading on a
measuring instrument.The calibration system considered in this
paper isshown in Fig. 1. The calibrator (standard) is the sourceof
the standard signal, and the standard value of thecalibrator is
compared with the measurement resultindicated by the EUT.
Verification is an activity performed by a nationalmeasurement
service in which similar measurementprocedures are used as for
calibration.
The overall measurement error consists of twocomponents: the
error arising in the EUT and thatoriginating from the measurement
standard [1]. It isworth mentioning that good measurement has
itsorigins as much in the study of errors or uncertainties ofthe
measurement as it does from the choice of theprinciple of
measurement [2]. When reporting the resultof a measurement of a
physical quantity, it is thereforealso necessary to state the
relevant error or uncertaintyof the measurement.
Uncertainty of measurement is a parameter associ-ated with the
result of a measurement that characterizesthe dispersion of the
values that would reasonably beattributed to the measurand [3].
Figure 2 illustrates the meaning of uncertainty anderror of
measurement using the normal distributioncurve and shows a
situation where the confidenceinterval ranges from 2s to + 2 s
which corresponds toan uncertainty of 2s at about 95.45 %
confidence level,where s is the standard deviation. In
metrologicalpractice the confidence interval is usually assumed to
befrom 2 s to + 2s or from 3 s to + 3s [3, 4]. In Fig. 2,the true
value is 1s and the EUT reading is 0, so theerror is + 1s .
5O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
UNCERTAINTY
Uncertainty of thecalibrating instrument,confidence in
themeasurement process andthe relation between them
TADEUSZ SKWIRCZYNSKIIndependent Consultant, Warsaw, Poland
Calibrator (test signal) EUT
EUT reading
Fig. 1 Measurement system used in calibration
-
6 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
Fig. 2 Error and uncertainty
Fig. 3 Illustration of incorrect test decisions for 2s
specifications for calibrator and EUT and normal distribution of
errors in their populations
-
7O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
2 Test uncertainty ratio (TUR)
The TUR for a measurand is defined as the standarduncertainty of
the EUT divided by that of the calibratinginstrument (measurement
standard) used to test it [4, 5,6]. A reliable TUR is only obtained
when thespecifications for the EUT and the calibratinginstrument
are correlated according to their errordistributions and confidence
intervals. It can be saidthat a reliable TUR is a sine qua non
condition for goodquality calibration. The purpose of calibration
is to gainconfidence that the EUT is capable of makingmeasurements
within the specifications. And, generally,the purpose of
measurement is to gain confidence thatthe value of the measurand is
within its tolerance limits.Testing laboratories need to use
measuring instrumentsthat have uncertainty specifications which are
adequatefor the measurements they perform.
3 Incorrect test decisions and confidence inthe measurement
process
Actual measuring instrument test results can containfour kinds
of test decisions:
acceptance of good units, rejection of bad units, rejection of
good units, and acceptance of bad units.
The ideal situation is that the results consist ofonly the first
two kinds of test decisions, the second twobeing the results of
uncertainty in the specifications forboth the EUT and the
calibrating instrument.
An accepted good unit is a calibrated instrumentthat is within
its specified tolerance limits and a rejectedbad unit is one that
is outside its tolerance limits.Thus, the actual test results
contain correct andincorrect test decisions. Correct test decisions
containacceptance of good units and rejection of bad unitswhereas
incorrect test decisions contain rejection ofgood units (incorrect
fail) and acceptance of bad units(incorrect pass). This situation
is shown in Fig. 3 for a5:1 TUR, normal error distribution and 2s
specificationsfor both the EUT and the measuring
instrument(calibrator). In this example, the normal
distributioncurve N (0, 1) - where 0 is the mean value and 1 is
thestandard deviation - illustrates the error distribution forthe
calibrator and the normal distribution curve N (2, 5)shows the
error distribution for the EUT.
As illustrated, the actual output of the calibrator islarger
than the nominal output by the maximumpermissible error, i.e. by +
2s . Relative to the EUT
specification, the calibrator output is at + 0.4s . In termsof
the test limits, the EUT readings which are trulywithin the
tolerance limits are in the range from 1.6sto + 2.4 s . This is due
to the fact that the readings have anormal distribution and so they
are symmetricallydistributed on either side of a stimulus that is
displacedby + 0.4 s from its nominal value. That is why the
EUTreadings between + 2s and + 2.4 s will be incorrectlyoutside the
tolerance limits and the readings between 2s and 1.6 s will be
incorrectly within them. As thedistribution of errors is normal,
the number of EUTunits within the tolerance limits that are
incorrectlyrejected exceeds the number of EUT units which
areoutside the tolerance limits that are incorrectlyaccepted.
Furthermore, as the error distribution is normal sothe curve is
symmetrical, and analogous results of theanalysis will be obtained
when the output of thecalibrator is displaced to 2s , i.e. to 0.4s
relative to theEUT specification.
The decimal fraction of correct test decisions equals1 minus the
decimal fraction of incorrect test decisions(incorrect fail plus
incorrect pass). The larger is thefraction of correct test
decisions, the larger will be theconfidence in the measurement
process. It is generallyassumed that 100 % correct test decisions
is unat-tainable at any cost. On the other hand, there is usuallya
target value for the correct test decision percentage.This
percentage depends on the activity supported bythe testing. The
percentage of correct test decisionsbelow the target value will
significantly decreasereliability of test results and confidence in
themeasurement process and may be assumed to haveunacceptable
effects on such factors supported by thetest as human health,
safety and lives, and cost ofmanufacturing or quality of product,
to mention just afew of them.
4 Results of analysis and discussion
The incorrect test decisions have been studied as afunction of
the TUR value ranging from 1:1 to 100:1 at2 s and 3 s confidence
intervals and normal errordistribution for both the EUT and the
calibrator.
The results of the study are given in the form ofgraphs in Figs.
47. The graphs contain the error of thecalibrator in standard
deviations, as an independentvariable, and the following decimal
fractions of the EUTpopulation as dependant variables:
good units rejected (incorrect fail units) in Figs. 4and 6,
and
bad units accepted (incorrect pass units) in Figs. 5and 7.
-
8 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
Fig. 4 Distribution of incorrect fail test decisions as a
function of calibrator error for 2 s specifications
Fig. 5 Distribution of incorrect pass test decisions as a
function of calibrator error for 2 s specifications
Fig. 6 Distribution of incorrect fail test decisions as a
function of calibrator error for 3 s specifications
Fig. 7 Distribution of incorrect pass test decisions as a
function of calibrator error for 3 s specifications
-
9O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
Graphs 4 and 5 refer to 2s specifications and graphs6 and 7
refer to 3s specifications for both the EUT andcalibrator
populations and normal distribution in theEUT population. The
curves given in Figs. 47 refer tothe following TUR values (curves
from top to bottom):1:1, 1.5:1, 3:1, 4:1, 5:1, 10:1, 20:1, 100:1.
The incorrectfail unit fraction and incorrect pass unit fraction of
theEUT population can be obtained from relevant values ofthe
cumulative distribution function. It can be seen fromthe data in
the Figures that the percentages of incorrecttest decisions, and
thus the percentage of correct testdecisions, depend strongly on
the TUR value and theconfidence interval. The percentage of correct
testdecisions increases when the TUR or confidence
intervalincreases.
But increasing the TUR requires the use of measur-ing
(calibrating) instruments of higher accuracy, whichcan be more
costly. An increase in the confidence inter-val increases the
uncertainty of measurement. As long asthe minimum TUR is met or
exceeded, the uncertaintiesof the measurement standard when
assigning anuncertainty to the calibration can be ignored.
The results of analysis indicate that 2s confidenceinterval
specifications require a much larger TUR valuethan 3 s confidence
interval specifications in order toensure the same percentage of
correct test decisions. Forexample, assuming the 3:1 TUR, the
percentage of in-correct fail test decisions is circa 6.85 % (see
Fig. 4) andthe percentage of incorrect pass test decisions is
circa1.89 % (see Fig. 5) for 2s specifications when the cali-brator
output is just within specifications at the 2slimit. For the same
TUR, the percentage of incorrect failtest decisions is circa 2.14 %
(see Fig. 6) and the per-centage of incorrect pass test decisions
is circa 0.13 %(see Fig. 7) for 3s specifications when the
calibratoroutput is just within specifications at the 3s limit.
It is necessary to increase the TUR more than twotimes, i.e. to
more than 6:1 for 2s specifications if thepercentage of incorrect
fail test decisions is not toexceed 2.14 % too. The percentage of
incorrect pass testdecisions circa 0.13 % for 2s specifications is
at circa85:1 TUR. The last condition requires using veryaccurate
measurement standards to perform the meas-urement.
In some cases it is possible to find measuredinstruments with
the uncertainty being de facto nearlythe same as the uncertainty of
the calibrating instru-ment used to calibrate them, i.e. the TUR is
about 1:1. Inthe case of 2s specifications, taking into
considerationthe data from Figs. 4 and 5 for 1:1 TUR, one can say
thatabout 50 % of test decisions would be incorrect, i.e.about 47.7
% of the good EUT units would be rejected(Fig. 4) and about 2.27 %
of the bad EUT units would beaccepted (Fig. 5), when the calibrator
output is justwithin specifications at the 2s specification
limit.Similarly, in case of 3s specifications, the percentage
of
incorrect test decisions would be about 50 % too, i.e.about 49.8
% of the good EUT units would be rejected(Fig. 6) and about 0.14 %
of the bad EUT units would beaccepted (Fig. 7), when the calibrator
output is justwithin specifications at the 3s specification limit.
Asone assumes normal error distribution in the
calibratorpopulation, about 2.28 % of that population for
2sspecifications and about 0.14 % for 3s specificationswill fall
under this condition.
There are some practical activities in science andtechnology
fields where TUR values as large as 100:1 arerequired. Such TUR
values enable a high reliability oftest results and high confidence
in the measurementprocess to be obtained. In such cases the
percentage ofincorrect test decisions would be as low as about 0.22
%when the calibrator error is just within specifications atthe 2s
specification limit (see Figs. 4 and 5) for 2sspecifications and
incorrect test decisions as low asabout 0.027 % when the calibrator
error is just withinspecifications at the 3s specification limit
(see Figs. 6and 7) for 3s specifications.
5 Two examples of a lack of specificinformation on the TUR
A lack of adequate or complete specific information onthe TUR
can be noticed even in some official documentsand measurement
procedures. In effect, in such casesinexperienced persons can have
some difficulties inmaking proper measurements. For illustration,
twoexamples concerning measurement uncertainty require-ments of
standards are discussed below.
ISO 10012-1 standard [7]
The requirements on the TUR arise from clause 4.3 ofthis
standard, which reads: The error attributable tocalibration should
be as small as possible. In most casesof measurement, it should be
no more than one thirdand preferably one tenth of the permissible
error of theconfirmed equipment when in use. If normal
errordistribution is assumed for both the EUT and thecalibrating
instrument then the TUR is 3:1 for the lowerpermissible limit of
error ratio, according to the above-mentioned requirements of the
standard.
Thus, even for 3s specifications (see Figs. 6 and 7),there will
be about 2.28 % of incorrect test decisionswhen the calibrating
instrument error is just withinspecifications at the 3s
specification limit, and asmuch as about 8.7 % of incorrect test
decisions for 2s
-
specifications (see Figs. 4 and 5) when the
calibratinginstrument error is just within specifications at the
2sspecification limit.
IEC 60373 [8] and IEC 60645-1 [9] standards
The requirements on measurement uncertainty for themechanical
coupler arise from clause 5.1 of IEC 60373,which reads: The
calibration uncertainty shall notexceed 1.0 dB for frequencies up
to and including 2 kHznor shall it exceed 2 dB for frequencies up
to andincluding 8 kHz. The mechanical coupler is a piezo-electric
transducer, which is used in calibrating thestimulus level of the
audiometer bone conduction. Thempe for the stimulus level of the
audiometer is 3 dBfor frequencies up to and including 4 kHz
[9].
Assuming normal error distribution for the stimuluslevel for
both the audiometer and mechanical couplerone has a 1.5:1 TUR value
at 3 kHz. At this frequency,taking into consideration results of
the analysis givenabove (see Figs. 47) one can draw the
followingconclusions. If the mechanical coupler used forcalibration
of audiometers and the audiometers arecalibrated according to these
standards, there will beabout 15.9 % of incorrect audiometer test
decisions for3s specifications, i.e. 15.9 % of incorrect rejections
orincorrect acceptances of audiometers, when the error ofthe
mechanical coupler is just within specifications atthe 3s
specification limit and as much as about 25.2 %of incorrect
audiometer test decisions for 2s specifi-cations when the error of
the mechanical coupler is justwithin specifications at the 2s
specification limit.
6 Conclusions
Results of the study indicate the way in which the TURand
confidence interval affect the incorrect testdecisions and thus the
correct test decisions, reliabilityof test results and confidence
in the measurementprocess.
Larger TUR values and confidence intervals signifylower
percentages of incorrect test decisions, higherreliability of test
results and higher confidence in themeasurement process.
But larger TUR values require the calibratinginstrument to be of
higher accuracy, which usuallyimplies a higher cost. A larger
confidence intervalsignifies a higher uncertainty of
measurement.
As long as the minimum TUR is met or exceeded, atan assumed
value of confidence interval, the uncertain-ties of the measurement
standard (or, generally, of themeasuring instrument) when assigning
an uncertaintyto the calibration or measurement can be ignored.
K
7 References
[1] Finkelstein, L., Grattan, K.T.V., Eds., ConciseEncyclopedia
of Measurement & Instrumentation,Oxford, New York, Seoul,
Tokyo, Pergamon Press,1994
[2] Sydenham, P.H., Ed., Handbook of MeasurementScience, Vol. 1,
Chichester, New York, Brisbane,Toronto, Singapore, John Wiley &
Sons, 1982
[3] International Vocabulary of Basic and GeneralTerms in
Metrology (VIM), BIPM, IEC, IFCC, ISO,IUPAC, IUPAP, OIML - ISO,
Geneva, 1993
[4] Guide to the Expression of Uncertainty in Meas-urement
(GUM), BIPM, IEC, IFCC, ISO, IUPAC,IUPAP, OIML - ISO, Geneva, 1995
(Corrected &reprinted edition)
[5] Turzeniecka D., Study of Results of Comparison ofSelected
Uncertainties, Metrology and MeasuringSystems, Vol. V, 1-2, PWN,
Warsaw, 1998
[6] Calibration: Philosophy in Practice, 2nd Ed.,
FlukeCorporation, 1994
[7] ISO 10012-1, Quality assurance requirements formeasuring
equipment-Part 1: Metrological con-firmation system for measuring
equipment, ISO,Geneva, 1993
[8] IEC 60373, Mechanical coupler for measurementson bone
vibrators, IEC, Geneva, 1990
[9] IEC 60645-1, Pure-tone audiometers, IEC, Geneva,1992
10 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
TADEUSZ SKWIRCZYNSKI
Independent Consultant,Warsaw, Poland
The author welcomes comments from readers and may be contacted
by e-mail: [email protected]
-
Abstract
The provision of the mass scale below one kilogram isachieved by
subdivision. This paper describes one of themethods used by INM
including details of the weighingtechniques, weighing schemes,
equipment used and theuncertainty of measurement of all the
standards involved.
1 Introduction
INM is the custodian of the Prototype Kilogram No. 2.As such, it
is INMs task to propagate the Romanianmass scale by subdivision and
multiplication of thekilogram.
Class E1 weights ensure traceability to the nationalmass
standard (the value of which is derived from theInternational
Prototype of the kilogram, maintained bythe BIPM) and weights of
Class E2 and lower [1]. Theyare used as standards at the thirteen
Romaniancalibration laboratories.
2 Test procedures
The set (500...1) g of Class E1 weights usually has thefollowing
composition:
500 g, 200 g, 200* g, 100 g50 g, 20 g, 20* g, 10 g
5 g, 2 g, 2* g, 1 g
The 1 kg reference standard, of known mass, is usedfor
calibration. Mass determinations are carried out bysubdivision (to
link standards having different nominalvalues up with a reference
standard). Depending on theweighing scheme, this procedure requires
a specificminimum number of standards. By the method of
leastsquares adjustment, the mass departures and theirstandard
deviations are calculated.
Weighing is always carried out as substitutionweighing, i.e.
single weights or combinations are alwayscompared with another
combination of the samenominal value. The difference between the
balanceindications has the symbol D m and it is necessary toapply
air buoyancy corrections to the observed weighingdifferences.
If y is the new corrected difference, this gives:
y = D m + ( r a r o)(V1 V2) (1)
where:
y is the corrected indication;D m is the difference in balance
readings calculated
from one weighing cycle (RTTR, where R is thereference standard
and T is the test weight);
r o = 1.2 kg m-3, the reference air density;
r a = air density at the time of the weighing; andV1, V2 are the
volumes of the standards (or the total
volume of each group of weights) involved in themeasurement.
In designing the scheme, all the masses from 1 kg to1 g are
broken down into decades. A weighing schemewith 12 equations per
decade is used in the calibration[1]. The first decade includes the
1 kg standard.
For subsequent decades the role of the standard istaken by the 1
from the previous decade; thus the100 g, 10 g masses become
intermediate standards,whose uncertainty is propagated directly to
masses inthe decade they head and hence to those in
subsequentdecades.
With the reference standard, the mass havingnominal values: 500
g, 200 g, 200* g, 100 g, S 100 g (thesum of 50 g, 20 g, 20* g and
10 g from the next decade)shall be calibrated using a 1 kg mass
comparator. Theobservations are of the same accuracy (for all
masscomparisons the same balance was used in the firstdecade).
Once all the weighings have been completed, the firststep
consists in the formation of the design matrix.
Matrix X contains the information about theequations used (the
weighing scheme) and matrix Ycontains the measured differences from
these equations.
11O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
WEIGHTS
Test procedures for Class E1weights at the RomanianNational
Institute ofMetrology: Calibration ofmass standards by sub-division
of the kilogram
ADRIANA VLCU, Romanian Bureau of LegalMetrology, National
Institute of Metrology,Romania
-
Denote:
X = (xij);i = 1...n;j = 1...k;xij = 1, 1 or 0;b is (b j) vector
of unknown departures; andY is (yi) vector of measured values
(including buoyancy
corrections).
1000 g 500 g 200 g 200* g 100 g S 100* g
The first row of the matrix represents difference inmass between
the +1 and the 1 weight, for example:(500 + 200 + 200* + 100) 1000
= y1
If (XT X) is the matrix of the normal equations, thisgives:
(XT X) b = XT Y (2)
where XT is a transpose of X:
The next step introduces two matrices: (XT X)-1 istermed the
inverse of (XT X) and the product (XT X)-1XT.
The matrix design contains only the weighingequations. For this
reason, the system can not be solvedbecause the determinant of (XT
X) is zero and theinverse (XT X)-1 does not exist.
To overcome this problem the Lagrangian multi-pliers method is
applied [3, 4] which consists of addingthe reference standard
(restraint mR) to the vector Y,the Lagrangian multipliers l to the
vector b , a linek + 1 and a column k + 1 (both containing the
elements1,0,1) to the normal equation and to the matrix XT
asfollows:
12 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
1 1 1 1 1 01 1 1 1 0 10 1 1 1 1 00 1 1 1 0 10 0 1 1 1 10 0 1 1 1
10 0 1 1 1 10 0 1 1 1 10 0 1 0 1 10 0 1 0 1 10 0 0 1 1 10 0 0 1 1
1
X =
1 1 0 0 0 0 0 0 0 0 0 01 1 1 1 0 0 0 0 0 0 0 01 1 1 1 1 1 1 1 1
1 0 01 1 1 1 1 1 1 1 0 0 1 11 0 1 0 1 1 1 1 1 1 1 10 1 0 1 1 1 1 1
1 1 1 1
XT =
2 2 2 2 1 12 4 0 0 0 02 0 10 0 0 02 0 0 10 0 01 0 0 0 10 01 0 0
0 0 10
XT X =
y1y2y3y4y5y6y7y8y9y10y11y12
Y =
y1y2y3y4y5y6y7y8y9y10y11y12mR
Y =
b 1b 2b 3b 4b 5b 6
b =
2 2 2 2 1 1 12 4 0 0 0 0 02 0 10 0 0 0 02 0 0 10 0 0 01 0 0 0 10
0 01 0 0 0 0 10 01 0 0 0 0 0 0
XT X =
-
The last column and row contains the factorhj = mj/mr, the
ratios between the nominal values of theunknown weights (mj) and
one of the reference (mr).
The best estimate of b , b for an over-determinedsystem of
equations X is given by:
b = (XT X)-1 XT Y (3)
3 Example of a least-squares analysis:Equipment, standards and
results
3.1 Equipment
The balances used in the measurements in the rangefrom 1 g to
500 g are listed below:
Type Max Standard Indicationdeviation, mg
AT 1005(Mettler) 1 kg 0.01 0.02 Digital
H20(Mettler) 160 g 0.01 Optical
2405(Sartorius) 30 g 0.002 Optical
Additionally, the mass laboratory is equipped withinstruments to
measure:
the pressure, measured using a standard barometer(U = 2 mbar, k
= 2);
the relative humidity, measured using a standardpsychrometer (U
= 3 %, k = 2); and
the temperature, measured using a standard thermo-meter (U = 0.4
K, k = 2).
From the air parameters, the air density is calculatedusing the
equation recommended by the CIPM [2].
3.2 Standards
The 1 kg reference standard is used as the known massfor the
calibration, where:
V = 127.7398 cm3, expanded uncertainty Uv = 0.0024 cm
3, k = 2. conventional mass mcr = 0.999 996 891 kg,
expanded uncertainty U(mcr) = 0.044 mg, k = 2.
The observed mass differences read:
The vector b with the unknown masses, accordingto equation (3)
above, gives:
13O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
1 1 0 0 0 0 0 0 0 0 0 0 01 1 1 1 0 0 0 0 0 0 0 0 01 1 1 1 1 1 1
1 1 1 0 0 01 1 1 1 1 1 1 1 0 0 1 1 01 0 1 0 1 1 1 1 1 1 1 1 00 1 0
1 1 1 1 1 1 1 1 1 00 0 0 0 0 0 0 0 0 0 0 0 1
XT =
0 0 0 0 0 0 10 1/4 0 0 0 0 1/20 0 1/10 0 0 0 1/50 0 0 1/10 0 0
1/50 0 0 0 1/10 0 1/100 0 0 0 0 1/10 1/101 1/2 1/5 1/5 1/10 1/10
0
(XT X)-1=
b 1b 2b 3b 4b 5b 6l
b =
3.7803.3911 0.04 0.050.010.010.0250.0280.0170.0170.0200.022
3.109
Y =
1000 g 3.109 mg500 g + 0.115 mg200 g + 0.075 mg200 g + 0.061
mg100 g + 0.020 mgS 100 g + 0.029 mg
b =
The inverse of XT X will be:
-
The value assigned to the summation S 100 g by thefirst decade
constitutes the restraint for the seconddecade with the individual
weights in the summationbeing calibrated separately in the second
series. Thesummation of weights S 10 g becomes the restraint forthe
third decade. Then, the same procedure is used forthe second and
the last decades.
4 Analysis of uncertainties
4.1 Type A uncertainty
If the adjusted mass difference of the weighingequations is Y =
X b , the residual for each equationis calculated as follows:
e = Y Y (4)
The calculation of e for the example gives theresults:
The standard deviation s of the observations iscalculated
by:
The residuals res. are the elements of the vector e ;n = n k + 1
represents the degrees of freedom (n kis the difference between the
number of performedobservations and the number of unknown weights;
1 isthe number of the restraints). According to this equationthe
standard deviation is:
s = 0.007 mg
The variance covariance matrix for b is given by:
Vb
= s2(XT X)-1 (6)
where the variances on the values of the solutions b aregiven by
the diagonal elements of the matrix (XT X)-1
denoted by cij. The off-diagonal elements of the matrixgive the
covariance between the weights.
The standard deviation (uncertainty of type A) of aparticular
unknown weight is:
The random uncertainty uA( b j) has a local com-ponent arising
from measurements in the currentdecade and after the first decade,
a propagatedcomponent arising from random uncertainty in
theintermediate standards.
4.2 Type B uncertainty
The components of type B uncertainties are:
4.2.1 Uncertainty associated with the referencestandard
where hj is described above.
14 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
2 10-3
2.1 10-3
10 10-4
05 10-3
5 10-3
2 10-3
5 10-3
9 10-3
9 10-3
8 10-3
8 10-3
e =
00.00350.00220.00220.00220.0022
mguA( b j) = s cij =ABB
0.02200.01100.00440.00440.00220.0022
mg (7)ur ( b j)= hj umcr =
0 0 0 0 0 0 10 1/4 0 0 0 0 1/20 0 1/10 0 0 0 1/50 0 0 1/10 0 0
1/50 0 0 0 1/10 0 1/100 0 0 0 0 1/10 1/101 1/2 1/5 1/5 1/10 1/10
0
Vb
= 0.000049
res2iABBBBni=1S
1n
s = (5)
-
4.2.2 Uncertainty associated with the air
buoyancycorrections
ub2
(b j) = (Vj hjVr)2
u2r a + ( r a r o)
2(u2Vj + hju2Vr) (8)
where:
Vj ,Vr = volume of test weight and referencestandard,
respectively;
u2r a = uncertainty for the air density;
r o = 1.2 kg m-3 is the reference air density;
u2Vj , u2Vr = uncertainty of the volume of test weight
and reference standard, respectively.
4.2.3 Uncertainty due to the display resolution of a digital
balance
For the first decade where a digital balance with thescale
interval of d = 0.01 mg is used, the uncertainty dueto resolution
is [1]:
(9)
4.3 Combined standard uncertainty
The combined standard uncertainty of the conventionalmass of the
weight b j is given by:
uc( b j) = [uA2(b j) + ur
2( b j) + ub
2(b j) + ud
2 ] 1/2 (10)
The summation contains all the contributions des-cribed
above.
4.4 Expanded uncertainty
The expanded uncertainty U (with k = 2) of the con-ventional
mass of the weights b j is as follows [8]:
5 Uncertainty budget for the first decade
Table 1 on page 16 shows the results obtained from theleast
squares analysis of the weighing data and theirassociated
uncertainties. It also lists the contributiondue to the uncertainty
in the value of the standard, in thebuoyancy correction and in the
balance.
6 Conclusions
A calibration scheme for mass standards below 1 kg hasbeen
described. The whole set of masses is calibrated,decade by decade,
in terms of a 1 kg standard.
The test procedure described leads to an efficientcalibration of
sets of class E1 weights, also used tocalibrate laboratory
standards with lower uncertainty.
The subdivision weighing scheme and the electronicmass
comparator used lead to an appreciable reductionin uncertainty in
each mass value, compared withprevious calibrations.
One way to reduce the uncertainty and to obtainbetter results is
to use balances of much greater ac-curacy and in near perfect
environmental conditions. K
Table 1 and References on page 16
15O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
00.00300.00110.00110.00060.0006
mgub(b j) =
0.04400.02520.01280.01280.01020.0102
0.0440.030.010.010.010.01
mg (11)=U = k uc(b j) =
0.02200.01260.00640.00640.00510.0051
mguc(b j) =
! 2 = 0.0041 mg
d / 2
3ud = ABAB
-
References
[1] OIML: International Recommendation R 111, Weights of classes
E1, E2, F1,F2, M1, M2, M3 (OIML, 1994)
[2] BIPM: Formule pour la dtermination de la masse volumique de
lairhumide (1991)
[3] Schwartz, R.: Realization of the PTBs mass scale from 1 mg
to 10 kg, PTB MA-21e /1991
[4] Schwartz, R.: Guide to mass determination with high
accuracy. PTB MA-40 /1991
[5] Romanowski, M.: Basic theory of the calibration of mass
standards[6] Riety, P.: Quelques nouveaux aspects sur ltalonage des
botes de masses en
srie ferme. BNM No 60 /1985[7] Vlcu, A: Greutat, i etalon cl.E1,
INM 1995[8] Benoit, J.M.: Ltalonnage des sries de poids, Travaux et
Mmoires du
BIPM, Tome XIII, 1907[9] Stuart Davidson and Sylvia Lewis:
Uncertainties in Mass Measurement.
NPLs analysis of data from the calibration of weight set NPLW
43. EurometProject No 231/1992
[10] Guide to the Expression of Uncertainty in Measurement
(GUM): BIPM, IEC,IFCC, ISO, IUPAC, IUPAP, OIML - ISO, Geneva, 1995
(Corrected & reprintededition)
ADRIANA VLCU,Romanian Bureau of
Legal Metrology,National Institute ofMetrology, Romania
16 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
t e c h n i q u e
Weights: 1 kg 500 g 200 g 200* g 100 g S 100 g
umr hj mg 0.022 0.011 0.0044 0.0044 0.0022 0.0022
Vr hj cm3 127.7398 63.8699 25.5480 25.5480 12.7740 12.7740
uVr hj cm3 0.0012 0.0006 0.0002 0.0002 0.0001 0.0001
Vj cm3 - 62.428 24.975 24.976 12.485 12.506
uVj cm3 - 0.014 0.004 0.004 0.002 0.001
r a mg/cm3 1.196
ur a mg/cm
3 0.002
(VjVr hj)u r a mg - 2.9 10-3 1.15 10-3 1.15 10-3 5.8 10-4 5.4
10-4
(r a r o)(u2Vj+u
2Vr)
1/2 mg - 5.6 10-5 1.61 10-5 1.61 10-5 8 10-6 4.3 10-6
ub mg - 0.003 0.0011 0.0011 0.0006 0.0005
ud mg 0.004
uA mg 0.0035 0.0022 0.0022 0.0022 0.0022
uc mg 0.022 0.0126 0.0064 0.0064 0.0051 0.0051
k 2
U mg 0.04 0.03 0.01 0.01 0.01 0.01
Table 1 Uncertainty budget for the first decade
-
Introduction
Determining the moisture content of grain andoleaginous foods is
just as important as determiningtheir protein content prior to
their sale. If the moisturecontent is too high, the grain must
first be dried toachieve a moisture content that is low enough for
thegrain to be stored - this is a costly and time-consumingprocess.
In addition, comminution of grain demands aspecific moisture
content and this requirement must becomplied with as closely as
possible. The moisturecontent of grain and oleaginous foods thus
has aconsiderable influence on the sale price which can beobtained;
consequently rapid and exact determination ofthe moisture content
during harvesting, storage andprocessing is of utmost economic
importance.
In Germany, hygrometers used in official or com-mercial
transactions must be verified before they can beused in the field -
in fact these instruments must be typeapproved by the
Physikalisch-Technische Bundesanstalt(PTB) for the grains and
oleaginous foods they areintended to measure.
In accordance with the procedure applied, hygro-meters are
classified into measuring instruments used:
to determine the moisture content by drying; and to measure a
moisture-dependent physical quantity
such as electrical resistance, capacitance or reflection,or
absorption of near infrared radiation.
Measurements whereby the moisture content isdetermined by drying
the grain and subsequentlydetermining the loss of mass are
generally too expensiveand time-consuming for trade in cereals:
results areobtained more rapidly by devices which determine
themoisture content by measuring a physical quantity.
Near infrared transmission spectral analyzer
In April 1998, a device which works on a new measuringprinciple
was approved in Germany for the measure-ment of the moisture
content of wheat, rye, barley andtriticale in the range from 10 %
to 20 % (See Fig. 1).Further approvals have been granted in the USA
(FGIS),Canada (CGC), Argentina (I.A.S.C.A.U), Denmark
(PlantDirectory) and South Africa (Wheat Board).
Description of the measurement principle
The functional principle of an N.I.T. (Near
InfraredTransmission) device is depicted in Fig. 2:
- Light from a halogen lamp is directed onto a mono-chromatic
mirror.
- This mirror generates monochromatic radiation in thewavelength
range between 800 nm and 1100 nm.
- With the aid of an electronic-mechanical control tech-nique,
the wavelength range from 850 nm to 1050 nmis applied to the sample
at wavelength steps of 2 nm.
- Part of the light is reflected or absorbed by the sample;the
other part, the transmitted light, is received by adetector.
The absorption of light varies as a function of thecomposition
of the different sample components, suchas moisture, protein, fat
and fiber structure, theabsorbance being decisively determined by
the layerthickness of the sample. Measuring vessels with a
layerthickness of 18 mm are used for wheat, rye, barley andspelt
and a measuring cell with variable layer thicknessis used for other
grains to be measured. The requiredlayer thickness is set in line
with the grains to bemeasured with the help of a servomotor.
17O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
e v o l u t i o n s
MOISTURE MEASUREMENT
Near infrared transmittancefor measuring the moisturecontent of
grains
KILIAN CONRADI, Verification Board of Rhineland-Palatinate,
Germany
Fig. 1 The Foss Infratec 1229 Grain Analyzer
-
Measurement is started with a scan, without thesample, carried
out as a reference measurement over thewhole wavelength range. The
detector system thusdetermines the light intensity furnished by the
system.Subsequently, after having been filled into the
samplefunnel, the sample is automatically transported to
themeasuring vessel. In the course of the measurement,
theintensities of the 100 selected wavelengths are deter-mined.
Then the absorbance values are calculated by thecomputer system.
The values obtained furnish a spectro-gram with peaks which are
characteristic of the samplemeasured.
From Fig. 3, the moisture and protein values canthen be
determined with the aid of a calibrationtranscribed via the network
(see below) or copied froma floppy disk.
The calibrations for the individual components aredefined by the
instrument manufacturers, in terms ofsuitable laboratory reference
procedures, by anadjustment calculus according to the least
squaresmethod. The PTB then checks these calibrations and,
ifcorrectness has been proved, grants an approval. Fromthe
verification law point of view, only the moisturevalue is of
significance though various interested partiesalso request a
verified determination of the proteincontent. This is why the
possibility is being consideredof evaluating the calibrations with
respect to the proteincontent within the scope of a special
test.
The advantages of the N.I.T. procedure over the othermethods of
measurement are the following:
the sample must not be bruised for the analysis; prompt
measurement results; the measurement results are independent of
sample
temperature and ambient temperature; simultaneous determination
of several quality charac-
teristics (e.g. moisture and protein); measuring devices with
networking capability.
During a single measurement process the devicecarries out ten
individual measurements. The samplequantity (which varies between
300 g and 500 g) is fed to
the device without having been bruised (see Fig. 4).
Themeasuring cycle then takes approximately 40 seconds,following
which the measurement result is indicated onthe digital display. In
addition, the standard deviation ofthe ten individual measurements
can be retrieved, whichallows conclusions to be drawn concerning
samplehomogeneity.
The NITNET network
The analyzers can be used most efficiently when they
areinterconnected by a network. At present, four N.I.T.networks
exist in Germany:
Doemens Calibrierdienst (DOEMENS-NITNET) nearMunich;
Raiffeisen HG Nord (RHG-NITNET) in Hanover; Network
Rhineland-Palatinate (RLP-NITNET) in
Leideneck; VDLUFA Network (VDLUFA-NITNET) in Kassel.
Approximately 180 N.I.T. analyzers are intercon-nected within
these four networks which are inde-pendent of each other. They are
connected as satellites totheir network operator in a star pattern
via a modemand transcription to, or modification of, the
calibrationson the individual devices is possible only via this
modemfrom the central processing unit of the networkoperator. This
prevents manipulation of the calibrationsby the measuring
instrument user.
Verification
In contrast to the laboratory reference procedure andthe
electrical hygrometers, the N.I.T. devices determineonly the water
fraction which is molecularly bound inthe grain and not the water
possibly adherent to the
18 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
e v o l u t i o n s
Fig. 2 Functional principle of an N.I.T.
-
dish. It was, therefore, necessary to open up new pathsfor the
verification of these measuring instruments.
Foss submits the calibrations developed to the PTBfor
examination and approval. These calibrations aretranscribed to the
PTBs master device and checked forcorrectness. After that, the
three submasters available atthe verification authorities of
Bavaria, Lower Saxonyand Rhineland-Palatinate are compared with the
PTBsmaster (see Fig. 5). A maximum deviation of 0.2 %
ispermissible. With the aid of these submasters, the usersmeasuring
instruments are then verified in accordancewith the approval.
The first verification of grain analyzers in Germanytook place
in Rhineland-Palatinate in July 1998. To date,about 80 devices have
been verified in Rhineland-Palatinate and if subsequent
verifications are includedthe total result is 125
verifications.
Verification test
The verification technological test comprises:
(i) Functional test with granulate
Three measurements are carried out in succession witha granulate
specially produced for this purpose. Theindication must lie in the
interval 100 0.5. If thiscondition is not complied with, testing of
the device isstopped.
(ii) Comparison of the device tested with the submaster
Comparisons between the device tested and the masterare carried
out with two samples of each type of grainapproved. Any commercial
grain or seed can be used as
19O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
e v o l u t i o n s
Fig. 3 Graphical representation of a spectral analysis of
wheatwith the following component values:
Moisture: 20.4 %Protein: 14.0 %Spectral measuring range: 850 nm
to 1050 nmPoints of measurement: 100 (corresponding to a
resolution
of 2 nm)
Fig. 4 Filling of the grain sample to be measured
Fig. 5 Connection of submasters to PTBs master device
-
sample material. The moisture content of one of thesamples must
be between 11 % and 12 %, that of theother between 14 % and 15 %.
The grain may also bemoistened; care must, however, be taken that
the samplematerial is thoroughly moistened. This can be achievedby
ensuring a sufficiently long mixing time (about threedays).
Each sample must be measured three times by thesubmaster and
three times by the device tested. Themean values of the measurement
results obtained by thesubmaster and the device tested must not
deviate bymore than 0.2 %.
A problem encountered upon verification, inparticular on hot
days in rooms without air-conditioning, is that samples with higher
moisturevalues may dry out during measurement.
Practicalapplications have shown that the moisture value maychange
by 0.1 % during a test cycle involving a sub-master and the device
tested. When several devices areverified it is, therefore,
necessary to recheck themoisture value on the master after each
measurementcomprising three individual measurements. The timeand
effort required for this procedure are such that onlyfour to six
devices can be verified each day. Solutions aretherefore being
sought which will allow the annualsubsequent verification to be
carried out in futuretogether with the network operator in the form
of anintercomparison.
It is difficult to furnish reliable figures about meas-urement
stability due to the fact that all the deviceswhich were verified
were subsequently also calibratedfor various grains - this was
carried out just prior to the
subsequent verification. Furthermore the devices will
bemaintained and if necessary repaired. Therefore, themeasurement
error during verification cannot becompared to the measurement
error of moisture deter-mination after the device has been in
operation for oneyear. However, the reproducibility with a
deviation of 1digit (0.1 %) measurement results is very good.
Summary and conclusions
The new N.I.T. devices offer the possibility to determinethe
important quality characteristics of grain andoleaginous foods
quickly and without the risk ofoperator errors. Devices operated in
a network furnishresults with very small deviations not only for
moisturemeasurements, but also for other parameters such
asprotein.
Practical application will still have to show to whatextent the
correctness is guaranteed, in particular in thecase of grain whose
biological characteristics deviatefrom those serving as a standard,
where measurementstability is higher compared to hygrometers
whichmeasure electrical resistance or capacity.
Furthermore it has been shown that N.I.T. networkinstruments
considerably improve relations betweenproducers and traders, since
producers are certified andevery trader who is connected to the
network can supplyand certify a certain product quality. K
20 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
e v o l u t i o n s
KILIAN CONRADI, Verification Board ofRhineland-Palatinate,
Germany
-
One of Don Boscos most noteworthy pieces of work is ofparticular
relevance to the teaching of metrology: Ilsistema metrico decimale
ridotto a semplicit precedutodalle quattro operazioni
dellaritmetica ad uso degliartigiani e della gente di campagna
(literal translation:The decimal metric system reduced to
simplicity, pre-ceded by the four arithmetical operations of use to
crafts-men and country people), published by Paravia, Turin
in1846.
In Italy the decimal units system was introduced atthe same time
as a number of other innovations - thisalso happened to be the time
when the French armiesheaded by Napoleon Bonaparte invaded the
Kingdom ofPiemonte - although discussions on the uniformity ofthe
units system as a useful scientific tool had alreadystarted some
time before.
In 1793 when the French National Assembly beganstudying a new
units system based on the length of theEarth meridian, some Italian
States (Granducato diToscana, Repubblica Cisalpina, Repubblica
Ligure, Regnodi Sardegna, la Repubblica Piemontese) contributed
tothe French project, which is considered to be the mostexcellent
example of scientific cooperation over thetimes.
When the French armies arrived in Italy, conqueringits most
important nations, they introduced by law themetrication of the
units system - thus eliminating deiure the preceding systems.
In Piemonte that happened in 1809, but while themetrication law
began to be applied by sending the newunit standards and the
related conversion tables to themunicipalities, the Congress of
Wien (1814) alsorestored inter alia the old units system all over
Europe.
But the charm and the force of the initial idea onwhich the
decimal units system was based soon began tobe recognized by
intellectuals, although scientificinterests were often mixed in
with political motivations.
So, in Piemonte, a Royal Decree was promulgatedwhich provided
for the decimal metric system to beadopted as a mandatory units
system.
But the promulgation of a new law is not enough tochange
long-standing habits based on the use oftraditional weights and
measures units and on multiplesand sub-multiples originally
determined by means ofcontinuous multiplying and dividing by
two.
Disadvantaged people were a major hurdle to thediffusion of the
new decimal system because they pre-dominantly continued to use the
ancient weights andmeasures in their everyday businesses.
On the other hand, Public State Schools, which wereintroduced in
Piemonte in 1822, were not mandatoryand thus not able to help to
efficiently spread the wordabout the new system amongst ordinary
people.
However Public State Schools did contribute topromoting the new
decimal system by means of teach-ing courses - though these courses
were of morerelevance to educated people than to the common
mortallacking a sound mathematical and scientific back-ground!
The Central Government invited the local authoritiesto do their
best to increase the coverage and usage of thenew units system
throughout society.
The Roman Church, with its network structure andauthority based
on the medieval custom of acquiringand applying knowledge, played a
primary role incontributing to spreading the word concerning the
newunits system.
Don Boscos work was initiated in a very complexhistorical and
social landscape with the clear intentionof encouraging
disadvantaged people to use the newdecimal units in their everyday
businesses. His book isconceived as a dialog and such a choice was
not bychance since he knew, as a well established teacher, thathe
would have to use a friendly teaching tone to capturethe masses
attention.
The choice of the dialog form for his work wasdetermined as a
means to reduce or even eliminate thecultural distance between the
writer and disadvantagedreaders, in order to involve them in a
knowledge acquisi-tion process as gradually as possible.
Don Bosco dramatized his work by means of atheater play, which
was performed in the risingOratories of the Salesian Congregation
where the playcombined amusement, reflection and learned
instruc-tion.
Don Boscos work was published four years beforethe mandatory
introduction of the metric system inPiemonte and even before that,
Vicar Apostolic GeneralMons. Filippo Ravina advised parish priests
to con-tribute to spread word about the new units system.
The challenge that Don Bosco faced with enthusiasmwas not only a
pedagogic one but a social one too: byallowing common people to
understand the decimalmetric units system, he raised them to the
rank ofcitizens who were able to actively share in the eco-nomic
and social life of their community.
21O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
e v o l u t i o n s
ITALIAN HISTORY
The decimal units systemand San Giovanni Bosco: A singular
meeting betweenscience and pedagogy
SILVANA IOVIENO and LILIANA SMERALDO,Camera di Commercio di
Napoli, Italy
-
Don Boscos work was very successful amongcontemporaries and that
is witnessed by the twenty-eight thousand copies and more that were
sold, as wellas by the praise of Monsignor Filippo Farina, Bishop
ofAsti.
Efforts made by such illustrious men - Don GiovanniBosco and
others - should encourage our contempor-aries to reflect on the
need to foster and promote themetrology culture in order to equally
extend the scopeand application of metrology to non-academic
environ-ments. K
Bibliography
K.Kula Le misure e gli uomini dallantichit ad oggiEdizione La
TerzaSac...LemoyneMemorie bibliografiche di Don Bosco Vol II
S.B.Cavanese 1901S.Scrofani De pesi e delle misure e monete dItalia
di SaverioScrofani corrispondente dellIstituto Nazionale di Francia
Napoli 1812Tutto Misure Linsegnamento del Sistema metrico
decimaleEdizione Mortarino
22 O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U
LY 2 0 0 1
e v o l u t i o n s
SILVANA IOVIENOCamera di Commercio di Napoli, Italy
LILIANA SMERALDO
-
23
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
REDUCING TECHNICAL TRADEBARRIERS
Second Triennial Review ofthe WTO Agreement onTechnical Barriers
to Trade(TBT) Results and Scope
PROF. HENRI SCHWAMM, Honorary Professor of Economics, University
of Geneva
Why was there a need for a Triennial Review of the operation and
implementation of the WTO Agreement on Technical Barriers to
Trade?
In the first place, such a Review provides answers towhy the
Agreement was set up and how it hasfunctioned up to the present
time. It offers members ofthe WTO a chance to ask for
clarifications on thefunctioning of the Agreement, and also allows
them toagree on improvements that should be made to it. It isan
opportunity for the active participation of ISO (as anObserver) in
the discussions.
Four other Standards Organizations have Observerstatus in the
TBT Committee: the IEC (InternationalElectrotechnical Commission);
OIML (InternationalOrganization of Legal Metrology); the UN/ECE
(UnitedNations Economic Commission for Europe); and theOCED
(Organization for Economic Cooperation andDevelopment).
This Review equally allows thought to be given tothe means that
may be brought in to facilitate theeffective participation of
developing countries in theinternational standardization and
conformity assess-ment work.
Results of the Second Triennial Review in Genevawhich ended in
late 2000
The role of international standardization
International standards represent a vital element withinthe TBT
Agreement and play a major role in itsimplementation.
However - and herein lies a challenge - the TBTAgreement does
not provide any precise definition ofwhat a relevant international
standard actually is.This omission can be the source of serious
confusion intrade exchanges, and so the TBT Committee hastherefore
sought to put this right. A broad and thoroughdebate took place in
Geneva between the CommitteeMembers and the Observers; below are
some of theproblems raised and the solutions offered.
WTO member countries needed to agree on theeconomic
circumstances where particular standardscannot be regarded as
relevant. Japan, as party to noregional trade agreement, has
proposed that inter-national standards under the TBT Agreement must
not
This article was first published in the February 2001 edition of
theISO BULLETIN and the BIML is grateful to the Editor of the
ISOBulletin for kindly granting permission to reprint it.
Introduction to the TBT Agreement
The WTO (World Trade Organization) Agreement onTechnical
Barriers to Trade (TBT) - sometimes referred toas the Standards
Code - aims to reduce impediments totrade resulting from
differences between nationalregulations and standards.
Standards may vary from country to country. Havingtoo many
different standards makes life difficult forproducers and
exporters. The need for them to complywith different standards
often involves significant costs.If the standards are set
arbitrarily, they could be usedas an excuse for protectionism.
Standards could thenbecome obstacles to trade. In order to prevent
toomuch diversity, the TBT Agreement encouragescountries to use
international standards where theseare appropriate. It fully
recognizes the importantcontribution that international standards
and con-formity assessment systems (ensuring that the require-ments
of standards are met by given products andservices) can make to
improving efficiency of produc-tion and facilitating international
trade.
The development of international standards doesindeed reduce
potential market access across barriersfor imports on the home
market of each WTO membercountry, and reduces the potential
barriers to itsexports to third country markets as well. K
-
24
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
have adverse effects on competition in the relevantmarket such
as, for instance, preventing technologicaldevelopment, and should
not be given preference overcharacteristics or requirements of
specific regions whenthe needs or interests exist in other regions
as well.
Japan is also of the opinion that internationalstandards can no
longer cope with technologicaldevelopment, thereby lacking
universality, and conse-quently relevance, under the TBT
Agreement.
Canada and India highlighted the importance of aconsensus-based
decision-making process in inter-national standardization bodies.
The criteria requiredinclude: a balanced representation of interest
cat-egories, broad geographical representation, an appealsmechanism
for the impartial handling of any sub-stantial or procedural
complaints, and notification ofstandardization activities in
suitable media to affordinterested persons or organizations an
opportunity formeaningful contributions.
The TBT Committee noted that situations couldarise where no
relevant international standards for agiven product existed. Could
the concept of equival-ency as proposed by New Zealand be applied
as aninterim measure? New Zealand does not see anyconflict between
use of equivalency and the develop-ment of international standards.
Indeed, the former canbe an important stepping stone towards the
latter andhas merit as a means of reducing unnecessary obstaclesto
trade. Hong Kong shared this view. The TBT Com-mittee found it
useful to further explore the equivalencyof standards as a
temporary measure to facilitate tradein the absence of relevant
international standards.
The Committee also considered the particular roleof
international standards used as a basis for technicalregulations.
Assuming that differing internationalstandards covering the same
issue exist, they wouldimpose on countries adopting technical
regulations achoice between several relevant international
standards.The effect of such a choice would in turn
createunnecessary regulatory barriers to trade and thusnegatively
impact on the objectives of the TBT Agree-ment. When raising this
question, the European Union(EU) illustrated the point by the
following example. Ifuse of a specific standard within a technical
regulationis made mandatory, and country A incorporates oneamong
the variety of different international standardsdevoted to the same
subject, it is thereby complyingwith the obligation of the TBT
Agreement for membercountries to use international standards as a
basis fortechnical regulations. If countries B and C adopttechnical
regulations covering the same subject but usedifferent
international standards as a basis for theirmandatory regulation,
they are also observing theAgreement. Nevertheless the market
remains frag-mented, as countries A, B and C, although each
iscomplying with the Agreement, would require differentstandards as
a basis for mandatory regulation. Conse-quently those countries
could reject imports of productsmeeting different international
standards but coveringthe same issue.
Such a result would certainly not correspond to thespirit and
purpose of the TBT Agreement, the objectiveof which is to
facilitate trade and to reduce marketfragmentation, among others,
by means of the use of
In the wake of the GATT
The provisions of the GATT 1947 contained only ageneral
reference to technical regulations and stand-ards. A GATT working
group, set up to evaluate theimpact of non-tariff barriers in
international trade,concluded that technical barriers were the
largestcategory of non-tariff measures faced by importers.
After years of negotiations at the end of the TokyoRound in
1979, 32 GATT Contracting Parties signedthe pluriannual Agreement
on Technical Barriers toTrade (TBT) which laid down the rules for
preparation,adoption and application of technical
regulations,standards and conformity assessment procedures.
The new WTO Agreement on Technical Barriers toTrade, or TBT
Agreement, negotiated during theUruguay Round, strengthens and
clarifies theprovisions of the Tokyo Round Standards Code.
Itclearly distinguishes between technical regulations
andstandards.
The difference between a standard and a technicalregulation lies
in compliance. While conformity withstandards is voluntary,
technical regulations are bynature mandatory. They have different
implications forinternational trade. If an imported product does
notfulfill the requirements of a technical regulation, it willnot
be allowed to be put on sale. In the case ofstandards,
non-complying imported products will beallowed on the market, but
then their market share maybe affected if consumers prefer products
that meet localstandards.
Conformity assessment procedures are defined by theTBT Agreement
as technical procedures - such astesting, verification, inspection
and certification - whichconfirm that products fulfill the
requirements laid downin regulations and standards. Generally,
exportersbear the cost of these procedures. Non-transparent
anddiscriminatory conformity assessment procedures canbecome
effective protectionist tools. K
-
25
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
country or region. Consensus procedures should beestablished
that seek to take into account the views ofall parties concerned
and to reconcile any conflictingarguments.
Impartiality includes: access to participation in
work,submission of comments on drafts, consideration ofviews
expressed and comments made, decision-making through consensus,
obtaining of informationand documents, dissemination of the
internationalstandards, fees charged for documents, right
totranspose the international standards into regional ornational
standards, revision of the internationalstandards.
Effectiveness and relevance. To facilitate interna-tional trade
and prevent unnecessary trade barriers,international standards need
to be relevant andeffectively respond to regulatory and market
needs, aswell as scientific and technological developments
invarious countries. They should not distort the globalmarket, have
adverse effects on fair competition, orstifle innovation and
technological development. Inaddition, they should not give
preference to thecharacteristics or requirements of specific
countrieswhen different needs and interests exist in othercountries
or regions. Whenever possible, internationalstandards should be
performance-based rather thanbased on design or descriptive
characteristics.
Coherence. In order to avoid the development ofconflicting
international standards, it is importantthat international
standardizing bodies avoidduplication of, or overlapping with, the
work of otherinternational standardizing bodies. In this
respect,cooperation and coordination with other
relevantstandardization bodies is essential.
Development dimension. Constraints on developingcountries, in
particular, to effectively participate instandards development
should be taken into con-sideration in the standards development
process.Tangible ways of facilitating developing
countriesparticipation in international standards developmentshould
be sought. Developing countries should not beexcluded de facto from
the process. Provisions forcapacity building and technical
assistance withinstandardizing bodies are important in this
context.
According to the TBT Committee, these principlesand procedures
should also be observed when guidesand recommendations are
elaborated. ISO confirmedthat they are observed in the preparation
process of theCASCO guides.
The Committee agreed that regular information-exchange with
relevant bodies involved in the develop-ment of international
standards was useful and shouldbe reinforced.
international standards. It is the EUs understandingthat for
achieving this purpose such standards shouldbe coherent. The EU
therefore supports the ISO/IECprocedures the aim of which is to
avoid the coexistenceof conflicting standards. The EU also supports
theprinciple of singularity proposed by Brazil, accordingto which
for each area of standardization no more thanone international
standardizing body should be active.This body should produce a
single and coherent set ofinternational standards. International
standardizingbodies should act jointly or in cooperation in cases
ofoverlapping when their areas of activity converge, be itfor
scientific, technological or regulatory reasons. Thisis also
Mexicos point of view: in the case of two inter-national
standardizing bodies working in the samearea, a coordination
mechanism should be put in placeso as to avoid duplication.
ISO gave its assurance that it would report to theTBT Committee
on action taken to avoid duplicationand ensure consistency between
international stand-ards. ISO also promised to report on its
activities toaddress the specific needs of developing
countries.
Taking these suggestions fully into account, and inorder to
clarify and to strengthen the concept ofinternational standards
under the Agreement and tocontribute to the advancement of its
objectives, theTBT Committee adopted a list of six principles
thatshould be observed by international standardizingbodies:
transparency, openness, impartiality, and con-sensus, effectiveness
and relevance, coherence, develop-ment dimension.
Transparency. All essential information on currentwork
programmes, as well as on proposals forstandards under
consideration and on the finalresults should be made accessible to
all interestedparties in all WTO member countries.
Openness. Membership of an international standard-izing body
should be open on a non-discriminatorybasis to relevant bodies of
all WTO membercountries. This would include openness with respectto
participation at the policy development level and atevery stage of
standards development, such as:proposal and acceptance of new work
items, tech-nical discussions on proposals, submission ofcomments
on drafts, reviewing existing standards,voting and adoption of
standards and disseminationof adopted standards.
Impartiality and consensus. All relevant bodies ofWTO member
countries should be provided withmeaningful opportunities to
contribute to thedevelopment of an international standard so that
thestandard development process will neither privilegenor favour
the interests of a particular supplier,
-
26
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
The Committee is perfectly aware of the fact thatinternational
standardization is an area in whichdeveloping country participation
is still limited andconstrained. Some of the reasons identified for
thissituation are the lack of technical capacity, the locationof
technical secretariats and technical meetings, thetranslation of
international standards into nationallanguages, as well as other
constraints in the areas offinancial and human resources which
handicapparticipation in meetings. To assist in resolving
thisproblem, the Committee noted that it was important toprioritize
the international standardization activitiesrelated to products of
particular interest to developingcountries. It is also critical for
those countries to assessproducts/sectors of priority interest to
them for inter-national standardization, so that resources can
beappropriately targeted. Another solution is to
facilitateeffective participation by means of
informationtechnologies, such as using e-mail and
video-conferencing as alternatives to traditional
meetings.Switzerland expressed its hope that the Committeewould
develop a demand-driven technical cooperationprogramme related to
the TBT Agreement.
Conformity assessment procedures
The goal of conformity assessment is to ensure that
therequirements of standards and technical regulations aremet by
given products and services. This is critical inorder for buyers of
those goods and services to haveconfidence that legitimate
regulatory objectives are metand that the goods and services meet
their health, safetyand other needs. Undoubtedly, confidence in
theconformity assessment practices and procedures ofother countries
is also important to the facilitation oftrade.
Indeed, there is broad support from both developedand developing
countries for working towards the goalthrough the principle of one
standard, one test, andif required, one certification, one time, as
stated inthe First Triennial Review of the TBT Agreement.
Where debate continues, however, is as to thedifferent methods
of pursuing the principle. Differentmechanisms exist to facilitate
acceptance of results ofconformity assessments: mutual recognition
agree-ments (MRAs), voluntary cooperative agreementsbetween
domestic and foreign conformity assessmentbodies, government
designation, unilateral recognitionof results of foreign conformity
assessment, manu-facturers/suppliers declarations.
Japan thinks that the three principles of thestandards
development process (transparency, open-
ness and impartiality) should apply equally to thedevelopment
process of conformity assessment guidesand recommendations (such as
CASCO Guides andstandards) and documents developed by
internationaland regional systems for conformity assessment (suchas
IAF - International Accreditation Forum - Guidelinesfor CASCO
documents).
A new development, encouraged by the TBT Agree-ment, is the
conclusion of MRAs on the results ofconformity assessment
procedures, concluded betweencountries having established
confidence in each otherstesting bodies and procedures. The trend
to concludesuch MRAs is confined - to date - to the
developedcountries. For example, the European Union hasconcluded
MRAs for the results of conformity assess-ment with Australia,
Canada, New Zealand, Switzerlandand the United States. Plurilateral
MRAs seem to bemore cost-effective than bilateral ones.
Accreditation, that is based on internationalstandards and
Guides, represents an independent testof the technical competence
of conformity assessmentbodies. Broad global acceptance of
accreditation, whichaddresses both regulatory requirements and
marketneeds, has provided the basis for the emergence of anumber of
international and regional examples ofaccreditation agreements.
Further work is needed toencourage greater acceptance of these
agreements,particularly among regulators and the public,
andstronger participation from developing countries intheir
development.
The examination of other less formal approaches toconformity
assessment, including suppliers declara-tion of conformity, could
be encouraged in order todetermine the costs and benefits and which
industrialsectors would most benefit. The supplier may be
amanufacturer, distributor, importer, assembler orservice
organization. The TBT Committee noted abroad support for the
suppliers declaration procedureas specified in ISO/IEC Guide
22.
Private multilateral agreements between certifica-tion
organizations, such as the successful IEC systemfor Conformity
Testing and Certification of ElectricalEquipment (IECEE CB Scheme)
should also be studiedto assess applicability to other sectors.
Chile stated that conformity assessment was themost serious
problem for developing countries, requir-ing further concrete steps
to be taken by the Commit-tee. Developing country exporters, in
particular SMEs,in some cases find themselves faced with
conformityassessment requirements in export markets that
aredifficult to meet. According to the Committee, this canbe due to
the limited physical and technical resourcesfor national conformity
assessment, insufficient num-bers of accredited laboratories at the
national or
-
27
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
g) assess the respective advantages of bilateral asagainst
multilateral approaches, unisectoral asagainst multisectoral.
Overall assessment of the Second Triennial Review
The Second Triennial Review of the TBT Agreement hasallowed
substantial progress to be achieved in the rightdirection. Most
members of the Committee welcomedits balanced and forward-looking
outcome, whichrepresents a good basis for future discussions.
Every-body highlighted the importance of having setguidelines to be
used by international standardsorganizations for standards
development. While theseguidelines are viewed as a good
achievement, it remainsto be seen how they will work in practice.
For theUnited States, these principles can at any rate be usedin
the future to evaluate adverse trade implications ifand when they
arise.
ISO welcomes the fact that the TBT Committeewishes to strengthen
the cooperation between theinternational standardizing bodies and
its govern-mental delegations. For strengthened cooperation
goeshand in hand with greater mutual trust.
The unanimous agreement on the positive spirit andoutcome of
this Second Triennial Review augurs wellfor the future because it
represents, for developing aswell as for developed countries, a
better functioningand better balanced tool for trade facilitation
in theinterest of the international trading community as awhole.
K
regional level, high costs as well as legal difficulties
inobtaining foreign accreditation, difficulties in establish-ing
internationally recognized accreditation bodies,difficulties in
participating in international conformityassessment systems, as
well as difficulties related to theimplementation of ISO/IEC Guides
on conformityassessment procedures.
Canada is promoting a common global approachto conformity
assessment and believes that ISO/IECGuide 60 (Code of Good Practice
for conformity assess-ment), which is designed to promote equal
right ofaccess to conformity assessment worldwide, provides agood
framework for the performance of all conformityassessment bodies
whether governmental or nongovernmental, domestic or international.
However, thisGuide is not widely used and needs to be reviewed
andupdated, if necessary, to better meet the objectives ofthe TBT
Agreement. In the meantime, the ISO Commit-tee on Conformity
Assessment (CASCO) has decided toundertake the necessary work.
Before making a final decision on the best way toproceed, WTO
negotiators must at all costs keep anumber of key questions in
mind:
a) determine the costs versus advantages of the
variousapproaches;
b) eliminate any duplication of trial prescriptions;c) foresee
the same procedures for local, national and
regional or international bodies whether govern-mental or non
governmental;
d) reduce the charges weighing on industry andregulation
bodies;
e) take into account the needs of consumers;f) favour
non-discriminatory and transparent ap-
proaches that facilitate exchanges; and
More information on the TBT Agreement can be found on the
following web site:
http://www.wto.org/wto/english/tratop_e/tbt_e/tbt_e.htm
-
28
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
E Issuing Authority / Autorit de dlivrance
Physikalisch-Technische Bundesanstalt (PTB),Germany
R61/1996 - NL - 00.01Type MP ... (Class X(1))
Atoma GmbH, Traunreuter Strae 2-4, D-84478 Waldkraiburg,
Germany
This list is classified by IssuingAuthority; updated
informationon these Authorities may beobtained from the BIML.
Cette liste est classe par Autoritde dlivrance; les informations
jour relatives ces Autorits sontdisponibles auprs du BIML.
OIML Recommendation ap-plicable within the System /Year of
publication
Recommandation OIML ap-plicable dans le cadre duSystme / Anne
d'dition
Certified pattern(s)
Modle(s) certifi(s)
Applicant
Demandeur
The code (ISO) of theMember State in which thecertificate was
issued.
Le code (ISO) indicatif del'tat Membre ayant dlivrle
certificat.
For each Member State,certificates are numbered inthe order of
their issue(renumbered annually).
Pour chaque tat Membre, lescertificats sont numrots parordre de
dlivrance (cettenumrotation est annuelle).
Year of issue
Anne de dlivrance
The OIML Certificate System for Measuring Instruments was
introducedin 1991 to facilitate administrative procedures and lower
costsassociated with the international trade of measuring
instruments subjectto legal requirements.
The System provides the possibility for a manufacturer to obtain
an OIMLcertificate and a test report indicating that a given
instrument patterncomplies with the requirements of relevant OIML
InternationalRecommendations.
Certificates are delivered by OIML Member States that have
establishedone or several Issuing Authorities responsible for
processing applicationsby manufacturers wishing to have their
instrument patterns certified.
OIML certificates are accepted by national metrology services on
avoluntary basis, and as the climate for mutual confidence and
recognitionof test results develops between OIML Members, the OIML
CertificateSystem serves to simplify the pattern approval process
for manufacturersand metrology authorities by eliminating costly
duplication of applicationand test procedures. K
Le Systme de Certificats OIML pour les Instruments de Mesure a
tintroduit en 1991 afin de faciliter les procdures administratives
etdabaisser les cots lis au commerce international des instruments
demesure soumis aux exigences lgales.
Le Systme permet un constructeur dobtenir un certificat OIML et
unrapport dessai indiquant quun modle dinstrument satisfait
auxexigences des Recommandations OIML applicables.
Les certificats sont dlivrs par les tats Membres de lOIML, qui
ont tabliune ou plusieurs autorits de dlivrance responsables du
traitement des
demandes prsentes par des constructeurs souhaitant voir
certifier leursmodles dinstruments.
Les services nationaux de mtrologie lgale peuvent accepter les
certificatssur une base volontaire; avec le dveloppement entre
Membres OIML dunclimat de confiance mutuelle et de reconnaissance
des rsultats dessais, leSystme simplifie les processus dapprobation
de modle pour lesconstructeurs et les autorits mtrologiques par
llimination desrptitions coteuses dans les procdures de demande et
dessai. K
Systme de Certificats OIML:Certificats enregistrs
2001.022001.04Pour des informations jour: www.oiml.org
OIML Certificate System:Certificates registered
2001.022001.04For up to date information: www.oiml.org
-
29
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
E Issuing Authority / Autorit de dlivrance
National Weights and Measures Laboratory (NWML),United
Kingdom
R51/1996-GB1-01.01Type 8060 (Classes X(1) and Y(a))
Pelcombe Ltd, Main Road, Dovercourt, Harwich, Essex CO12 4LP,
United Kingdom
E Issuing Authority / Autorit de dlivrance
OIML Chinese Secretariat, St6ate Bureau of Technical
Supervision, China
R60/2000-CN-00.01Type CZL-3 (Class C)
Zhongyuan Electrical Measuring Instruments Co., P.O. Box 2,
Hanzhong 723007, Shanxi, China
R60/2000-CN-00.02Type CZL-8C (Class C)
Zhongyuan Electrical Measuring Instruments Co., P.O. Box 2,
Hanzhong 723007, Shanxi, China
R60/2000-CN-00.03Type CZL-6G (Class C)
Zhongyuan Electrical Measuring Instruments Co., P.O. Box 2,
Hanzhong 723007, Shanxi, China
R60/2000-CN-00.04Type CZL-6E (Class C)
Zhongyuan Electrical Measuring Instruments Co., P.O. Box 2,
Hanzhong 723007, Shanxi, China
R60/2000-CN-00.05Type CZL-6D (Class C)
Zhongyuan Electrical Measuring Instruments Co., P.O. Box 2,
Hanzhong 723007, Shanxi, China
E Issuing Authority / Autorit de dlivrance
Physikalisch-Technische Bundesanstalt (PTB),Germany
R60/2000-DE-01.01Type C16 i (Class D1 up to C4)
Hottinger Baldwin Messtechnic Wgetechnik GmbH,Im Tiefen See 45,
D-64293 Darmstadt, Germany
R60/2000-DE-01.02Type PW2 (Classes D1, C3, C3MR and C3MI)
Hottinger Baldwin Messtechnic Wgetechnik GmbH,Im Tiefen See 45,
D-64293 Darmstadt, Germany
R60/2000-DE-01.03Type RTN .. (Class C3 to C5)
Schenk Process GmbH, Landwehrstrae 55, D-64293 Darmstadt,
Germany
E Issuing Authority / Autorit de dlivranceDanish Agency for
Development of Trade and Industry, Division of Metrology,
Denmark
R60/2000-DK-01.01Compression, strain gauge load cell, type SC
(Class C)
Esit Elektronik Sistemler Imalat ve Ticaret Ltd. STI,Mhrdar Cad.
91 Kadiky, TR-81300 Istanbul, Turkey
R60/2000-DK-01.02Shear beam, strain gauge load cell, type SBS
(Class C)
Esit Elektronik Sistemler Imalat ve Ticaret Ltd. STI,Mhrdar Cad.
91 Kadiky, TR-81300 Istanbul, Turkey
R60/2000-DK-01.03Single point, strain gauge load cell, type SP
(Class C)
Esit Elektronik Sistemler Imalat ve Ticaret Ltd. STI,Mhrdar Cad.
91 Kadiky, TR-81300 Istanbul, Turkey
INSTRUMENT CATEGORYCATGORIE DINSTRUMENT
Automatic catchweighing instrumentsInstruments de pesage
trieurs-tiqueteurs fonctionnement automatique
R 51 (1996)
INSTRUMENT CATEGORYCATGORIE DINSTRUMENT
Metrological regulation for load cells(applicable to analog
and/or digital load cells)Rglementation mtrologique des cellules de
pese(applicable aux cellules de pese affichageanalogique et/ou
numrique)
R 60 (2000)
-
30
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
E Issuing Authority / Autorit de dlivrance
Laboratoire National dEssaisService Certification et Conformit
TechniqueCertification Instruments de Mesure, France
R60/2000-FR2-00.01SCAIME bending beam load cell with strain
gauges,Types APC.SH5e, APC.SH10e, APC.SH15e(Accuracy class C)
Scaime S.A., Z.I. de Juvigny, B.P. 501, F-74105 Annemasse cedex,
France
E Issuing Authority / Autorit de dlivrance
Netherlands Measurement Institute (NMi) Certin B.V.,The
Netherlands
R60/2000-NL1-01.01Type LBD1 (Class C)
Charder Electronic Co., Ltd, 103, Kuo Chung Road,Dah Li City,
Taichung Hsien 412, R.O.C., Taiwan
R60/2000-NL1-01.02Type 1130 (Class C)
Tedea Huntleigh International Ltd., 5a Hatzoran St.,Netanya
42506, Isral
R60/2000-NL1-01.03Type 0795 (Class C)
Mettler-Toledo Inc., 1150 Dearborn Drive, Worthington,Ohio
43085-6712, USA
R60/2000-NL1-01.04Type GD or 0782 (Class C)
Mettler-Toledo Changzhou Scale Ltd., 111 Changxi Road,
Changzhou, Jiangsu 213001, China
R60/2000-NL1-01.05Type CPI (Class C)
Precia S.A., BP 106, F-07001 Privas cedex, France
R60/2000-NL1-01.06Type 0785 (Class C)
Mettler-Toledo Inc., 150 Accurate Way, Inman, SC 29349, USA
R60/2000-NL1-01.07Type MED-400 (Class C)
HBM Inc., 19 Bartlett Street, Marlboro, MA 01752, USA
R60/2000-NL1-01.08 Rev. 1Type CA40X (Class C)
Scaime S.A., Z.I. de Juvigny, B.P. 501, F-74105 Annemasse cedex,
France
R60/2000-NL1-01.09Type 1130 (Class C)
Tedea Huntleigh International Ltd., 5a Hatzoran St.,Netanya
42506, Isral
R60/2000-NL1-01.10Type BCS (Class C)
CAS Corporation, CAS Factory # 19 Kanap-ri,Kwangjeok-myon,
Yangju-kun Kyungki-do, Rep. of Korea
E Issuing Authority / Autorit de dlivrance
Netherlands Measurement Institute (NMi) Certin B.V.,The
Netherlands
R61/1996-NL1-01.01Types CCW-M-****(*)-*/**-**,
CCW-EM-****(*)-*/**-**,CCW-NZ-****(*)-*/**-**,
CCW-RZ-****-*/**-**-N, CCW-DZ-****-*/**-**-N (Class X(1))
Ishida Co., Ltd., 44, Sanno-cho, Shogoin, Sakayo-ku,Kyoto-city
606-8392, Japan
R61/1996-NL1-01.02Type WT-WMA-2 (Class Ref(1))
Wet B.V., Minervum 1719, 4817 ZK Breda, The Netherlands
R61/1996-NL1-01.03Type Duplex Weighmaster (Class X(1))
Thiele Technologies Inc., 315, 27th Avenue
Northeast,Minneapolis, Minnesota 55418-2715, USA
R61/1996-NL1-01.04Model TW-.... (Class X(1))
Neupak, 3680-1 Dodd Road, St. Paul, MN 55122, USA
INSTRUMENT CATEGORYCATGORIE DINSTRUMENT
Automatic gravimetric filling instrumentsDoseuses pondrales
fonctionnement automatique
R 61 (1996)
-
31
u p d a t e
O I M L B U L L E T I N V O L U M E X L I I N U M B E R 3 J U LY
2 0 0 1
E Issuing Authority / Autorit de dlivrance
Physikalisch-Technische Bundesanstalt (PTB),Germany
R76/1992-DE-00.09 Rev. 1Type iso-TEST (Classes I, II, III and
IIII)
Sartorius A.G., Weender Landstrae 94-108, D-37075 Gttingen,
Germany
E Issuing Authority / Autorit de dlivranceDanish Agency for
Development of Trade and Industry, Division of Metrology,
Denmark
R76/1992-DK-01.01Type M1100-Cx (Classes III and IIII)
Marel hf, Hofdabakka 9, IS-112 Reykjavik, Iceland
E Issuing Authority / Autorit de dlivrance
Netherlands Measurement Institute (NMi) Certin B.V.,The
Netherlands
R76/1992-NL1-01.04Type 8217 (Class III)
Mettler-Toledo Inc., 1150 Dearborn Drive, Worthington, Ohio
43085-6712, USA
R76/1992-NL1-01.05Type SC600 (Class III)
Shekel Electronics Scales, Kibbutz Beit Keshet, M.P. Lower
Galilee 15247, Isral
R76/1992-NL1-01.06Type DT-15 (Class III)
DATECS Ltd.A, 125, Tsarigrag shosse, bl 26B, Sofia 1113,
Bulgaria
R76/1992-NL1-01.07Type IWQ-series (Class III)
Ishida Co., Ltd., 44, Sanno-cho, Shogoin, Sakayo-ku,Kyoto-city
606-8392, Japan
R76/1992-NL1-01.08Types AB-S, GB-S and PB-S (Classes I, II and
III)
Mettler-Toledo A.G., Im Langacher, CH-8606 Greifensee,
Switzerland
R76/1992-NL1-01.09Type BM-3 (Class III)
Digital Scales S.A., Poligono Industrial Larrondo,Beheko
Etorbidea, no. 2 Naves 2, 3, 4, 48180 Loiu Vizcaya, Spain
E Issuing Authority / Autorit de dlivrance
Gosstandart of Russian Federation, Russian Federation
R76/1992-RU-00.03Scale SHTRIKH M (Class III)
SHTRIKH-M, 1, Kholodilny pereulok, Moscow, 113191,Russian
Federation
E Issuing Authority / Autorit de