SIM.M.M-S14 MASS COMPARISON 200 mg, 1 g, 50 g, 200 g, 1 kg ...€¦ · Circulation of Draft A for comments/ editorial corrections May 2014 Final report. Draft B June 2014 4) Transfer

CENTRO ESPAÑOL DE METROLOGÍA. C/ Del Alfar, 2. 28760 Tres Cantos, Madrid | www.cem.es | [email protected]

SIM.M.M-S14

MASS COMPARISON

200 mg, 1 g, 50 g, 200 g, 1 kg and 2 kg

Final Report

Authors: Nieves Medina, Douglas Edgardo Brito, Wendy Lilieth Chinchilla,

Yanisareth Chow, Olman Fernando Ramos Alfaro, Renato José Reyes Valverde, Rómulo Salguero.

1) Outline The scope of the comparison is the demonstration of the coherency of the calibration of 200 mg, 1 g, 50 g, 200 g, 1 kg and 2 kg stainless steel mass standard weights as realized by the participating institutes. This comparison is based on a decision taken on August 27th, 2013 as part of the program PRACAMS (Regional Program for Quality Support and Implementation of Sanitary and Phytosanitary Measures in Central America). The protocol follows the rules of the “Measurement comparisons in the CIPM MRA” [1]. Each participating NMI was asked to determine the true mass and conventional mass of 200 mg, 1 g, 50 g, 200 g, 1 kg and 2 kg stainless steel mass standard weights. 2) Participants The Institutes participating in the comparison are:

Country National

Metrology Institute

Identification code Technical Contact

SPAIN CEM Pilot Nieves Medina Manuel Bautista

COSTA RICA LACOMET 1 Olman Fernando Ramos Alfaro Marcela Prendas

HONDURAS CEHM 2 Wendy Lilieth Chinchilla

NICARAGUA LANAMET 3 Renato José Reyes Valverde

PANAMA CENAMEP 4 Yanisareth Chow

GUATEMALA CENAME 5 Rómulo Salguero

EL SALVADOR CIM 6 Douglas Edgardo Brito

Jorge Adalberto Medrano Cabrera

MINISTERIO DE INDUSTRIA, ENERGÍA Y TURISMO. CENTRO ESPAÑOL DE METROLOGÍA

3) Timetable for the comparison

Activity Deadline Questionnaire and Protocol agreed August 2013

Measurements at the pilot laboratory facilities August 2013

Circulation and measurements by the participants September 2013

Return to pilot laboratory and control measurements February 2014

Elaboration of Draft A April 2014

Circulation of Draft A for comments/ editorial corrections

May 2014

Final report. Draft B June 2014

4) Transfer standards Details of the standard weights are listed below:

Identification Nominal mass

Density at 20 °C

(kg/m3)

Expanded uncertainty

(k = 2) (kg/m3)

AHJ 2 kg 7 972,1 0,5 AIJ 1 kg 7 971,68 0,18

BNE 200 g 7 963,0 0,5 B7W 50 g 7 958,3 1,1 BF6 1 g 8 001 27

200 mg 8 000 80

They are class E2 mass standard weights according to OIML R 111 [2]. 5) Procedure Each participating institute was asked to determine the true mass and conventional mass in air of the travelling standards. Two weeks were allowed for the laboratory measurements and one week for transportation between participants. Each participating institute was responsible for carrying the traveling standards to the next laboratory. 6) Determination of the reference value


The reference values have been provided by the pilot laboratory with direct traceability to the Pt-Ir prototype K24, which is traced to the IPK. The air density was determined according to the equation CIPM 2007 [3]. Two measurements were performed during the comparison, one at the beginning of the comparison and other at the end of the comparison. Although one participant reported that the weights arrived at its laboratory with their surface damaged, no significant drift has been found. In fact no weight showed drift apart from the 50 g weight, which drifted 9 micrograms, which is almost negligible. Anyway for this weight an additional contribution to the uncertainty has been taken into account; the drift taken as a rectangular distribution. The reference values, expressed as deviations from nominal value, and their standard uncertainties are provided in the following table:

Nominal mass

/g

Deviation from nominal value

(true mass)

/mg

Deviation from nominal value (conventional

mass) /mg

Standard uncertainty

(k = 1)

/mg 0,2 0,0090 0,0090 0,0010 1 0,0110 0,0110 0,0017

50 0,0595 0,0205 0,0072 200 0,260 0,125 0,017

1000 0,840 0,305 0,083 2000 1,80 0,75 0,17

The pilot laboratory could have provided lower uncertainties according to its CMCs, but it was decided not to do because the quality of the traveling standards (E2 weights).

7) Analysis of the results The aim of the comparison is to demonstrate the consistency of the results provided by the laboratories with the reference values. The method for the evaluation of the results is based on [4] and it is described as follows. The results are evaluated for each weight and for true mass and conventional mass separately. For each laboratory result, true mass or conventional mass, the difference between the laboratory result, vn, and the reference value, vref, is calculated as

dn = vn - vref

This parameter is called the difference from the reference value.

Every dn is associated with an uncertainty given by the following formula,

u²(dn) = un² + uref ² The same notation is used for both true mass and conventional mass results in Sections 8 and 9 with the meaning set by the context.


8) Results for true mass

a. 200 mg The results for the transfer standard of 200 mg are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,0099 0,0008 -0,0189 0,0026 no 2 0,0085 0,0036 -0,0005 0,0075 yes 3 0,0057 0,0034 -0,0033 0,0071 yes 4 0,0091 0,0025 0,0001 0,0054 yes 5 0,0040 0,0022 -0,0050 0,0047 no 6 0,0100 0,0080 0,0010 0,0161 yes

The values dn and their corresponding uncertainties U(dn) (k = 2) are shown in the following figure:

200 mg

1

23

4

5

6

-0,025

-0,020

-0,015

-0,010

-0,005

0,000

0,005

0,010

0,015

0,020

d n (m

g)

b. 1 g The results for the transfer standard of 1 g are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,0114 0,0036 -0,0224 0,0079 no 2 0,0075 0,0063 -0,0035 0,0130 yes 3 -0,0151 0,0052 -0,0261 0,0109 no 4 0,0110 0,0050 0,0000 0,0105 yes 5 0,0085 0,0026 -0,0025 0,0062 yes 6 0,0100 0,0070 -0,0010 0,0144 yes



1 g

1

2

3

45 6

-0,04

-0,03

-0,02

-0,01

0,00

0,01

0,02d n

(mg)

c. 50 g The results for the transfer standard of 50 g are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,007 0,008 -0,066 0,021 no 2 0,063 0,023 0,004 0,048 yes 3 0,100 0,017 0,041 0,038 no 4 0,070 0,013 0,011 0,030 yes 5 0,027 0,025 -0,033 0,052 yes 6 0,000 0,060 -0,060 0,121 yes



50 g

1

2

3

4

5

6

-0,20

-0,15

-0,10

-0,05

0,00

0,05

0,10

d n (m

g)

d. 200 g The results for the transfer standard of 200 g are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,263 0,019 -0,523 0,051 no 2 0,330 0,110 0,070 0,223 yes 3 0,210 0,066 -0,050 0,136 yes 4 0,280 0,050 0,020 0,105 yes 5 0,202 0,090 -0,058 0,183 yes 6 0,200 0,140 -0,060 0,282 yes



200 g

1

2

34

5 6

-0,7

-0,6

-0,5

-0,4

-0,3

-0,2

-0,1

0,0

0,1

0,2

0,3

0,4

d n (m

g)

e. 1 kg The results for the transfer standard of 1 kg are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,86 0,04 -1,70 0,18 no 2 0,88 0,44 0,04 0,90 yes 3 1,89 0,32 1,05 0,66 no 4 0,90 0,22 0,06 0,47 yes 5 0,30 0,45 -0,54 0,92 yes 6 0,00 0,70 -0,84 1,41 yes


1 kg

1

2

3

4

56

-2,5

-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

1,5

2,0

d n (m

g)

f. 2 kg The results for the transfer standard of 2 kg are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -1,99 0,42 -3,79 0,90 no 2 2,03 0,86 0,23 1,75 yes 3 1,32 0,78 -0,48 1,60 yes 4 2,20 0,40 0,40 0,87 yes 5 0,20 0,90 -1,60 1,83 yes 6 2,00 0,70 0,20 1,44 yes



2 kg

1

2

3

4

5

6

-6

-5

-4

-3

-2

-1

0

1

2

3

d n (m

g)

9) Results for the conventional mass

a. 200 mg The results for the transfer standard of 200 mg are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,0099 0,0008 -0,0189 0,0025 no 2 0,0085 0,0036 -0,0005 0,0075 yes 3 0,0059 0,0034 -0,0031 0,0070 yes 4 0,0091 0,0025 0,0001 0,0054 yes 5 0,0040 0,0021 -0,0050 0,0046 no 6 0,0100 0,0080 0,0010 0,0161 yes



200 mg

1

23

4

5

6

-0,025

-0,020

-0,015

-0,010

-0,005

0,000

0,005

0,010

0,015

0,020

d n (m

g)

b. 1 g The results for the transfer standard of 1 g are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,0114 0,0034 -0,0224 0,0076 no 2 0,0075 0,0063 -0,0035 0,0130 yes 3 -0,0152 0,0051 -0,0262 0,0107 no 4 0,0110 0,0050 0,0000 0,0105 yes 5 0,0085 0,0026 -0,0025 0,0062 yes 6 0,0100 0,0070 -0,0010 0,0144 yes



1 g

1

2

3

45 6

-0,04

-0,03

-0,02

-0,01

0,00

0,01

0,02

d n (m

g)

c. 50 g The results for the transfer standard of 50 g are contained in the following table

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,003 0,003 -0,023 0,016 no 2 0,024 0,023 0,004 0,048 yes 3 0,050 0,020 0,030 0,042 yes 4 0,031 0,013 0,011 0,030 yes 5 0,027 0,025 0,007 0,052 yes 6 0,000 0,060 -0,021 0,121 yes


50 g

1

2

34 5

6

-0,20

-0,15

-0,10

-0,05

0,00

0,05

0,10

0,15

d n (m

g)

d. 200 g The results for the transfer standard of 200 g are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,124 0,019 -0,249 0,052 no 2 0,190 0,110 0,065 0,223 yes 3 0,075 0,066 -0,050 0,137 yes 4 0,140 0,050 0,015 0,106 yes 5 0,202 0,090 0,077 0,183 yes 6 0,100 0,140 -0,025 0,282 yes


The values dn and their corresponding uncertainties U(dn) (k = 2) are shown in the following figure.

200 g

1

2

3

4

5

6

-0,4

-0,3

-0,2

-0,1

0,0

0,1

0,2

0,3

0,4d n

(mg)

e. 1 kg The results for the transfer standard of 1 kg are contained in the following table:

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,33 0,04 -0,63 0,19 no 2 0,35 0,44 0,05 0,90 yes 3 0,64 0,32 0,34 0,66 yes 4 0,37 0,22 0,07 0,47 yes 5 0,30 0,45 -0,01 0,92 yes 6 0,00 0,70 -0,31 1,41 yes

The values dn and their corresponding uncertainties U(dn) (k = 2) are shown in the following figure.


1 kg

1

2

3

4 5

6

-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

1,5

d n (m

g)

f. 2 kg The results for the transfer standard of 2 kg are contained in the following table

Participant vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

1 -0,94 0,42 -1,69 0,91 no 2 0,98 0,86 0,23 1,76 yes 3 0,90 0,78 0,15 1,60 yes 4 1,10 0,40 0,35 0,87 yes 5 0,20 0,90 -0,55 1,83 yes 6 1,00 0,70 0,25 1,44 yes


2 kg

1

2 34

5

6

-3

-2

-1

0

1

2

3

d n (m

g)


10) Conclusions The comparison was successful. There was no significant drift in the mass of any of the transfer standard weights and the measurements, analysis and reporting were completed according to the schedule. For all the results of laboratories 2, 4 and 6, the difference from the reference value is less in magnitude than the expanded uncertainty. For laboratory 5, this is also the case except for the 200 mg results where the difference from the reference value is about the same magnitude as the expanded uncertainty. For laboratory 3, the difference from the reference value is greater in magnitude than the expanded uncertainty for the 1 g results and for the 1 kg true mass result and about the same as the expanded uncertainty for the 50 g true mass and 200 mg conventional mass results. For laboratory 1, the difference from the reference value is greater in magnitude than the expanded uncertainty for all 10 results (5 true mass and 5 conventional mass). 11) References [1] http://www.bipm.org/utils/common/CIPM_MRA/CIPM_MRA-D-05.pdf [2] http://www.oiml.org/en/files/pdf_r/r111-2-e04.pdf [3] Revised formula for the density of moist air (CIPM-2007); Metrologia 45

(2008) 149-155. 12) Acknowledgments The pilot laboratory would like to thank the European Program of Quality Support and Application of Sanitary and Phytosanitary Measures in Central America (PRACAMS) for the support in this comparison.


ANNEX 1 Information supplied after Draft A report After draft A report was sent to all the participants, LACOMET reported new results. The new results for LACOMET are the following: True mass:

vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

0,0099 0,0008 0,0009 0,0026 yes 0,0114 0,0036 0,0004 0,0079 yes 0,0669 0,0075 0,0074 0,0208 yes 0,263 0,019 0,003 0,051 yes 0,859 0,040 0,019 0,185 yes 1,99 0,42 0,19 0,90 yes

Conventional mass:

vn

/mg

un (k = 1) /mg

dn

/mg

U(dn) (k = 2)

/mg |dn |< U(dn)

0,0099 0,0008 0,0009 0,0025 yes 0,0114 0,0034 0,0004 0,0076 yes 0,0277 0,0073 0,0072 0,0205 yes 0,124 0,019 -0,001 0,052 yes 0,327 0,040 0,022 0,185 yes 0,94 0,42 0,19 0,91 yes

As a conclusion, for all these new results, the difference from the reference value is less in magnitude than the expanded uncertainty. LACOMET expressed its desire to include this comment in the report annex after having received the draft A report: In the intercomparison processes performed by SIM, in general the correction value obtained in the calibration process is reported. In this opportunity, the correction value obtained and reported, by the LACOMET Mass Laboratory (Costa Rica), did not match with the error value requested in the Annex C of the Protocol of the intercomparison, this because, based in the term "measurement error" of the VIM, measurement errors as inverse values of these corrections, together with the corresponding corrections were reported. This can be concluded from the preliminary report (Draft A). The initial data reported by the LACOMET Mass Laboratory (Costa Rica); after taking into account the concept of error used in the Protocol of the intercomparison, were considered erroneous due to confusion brought on in the


application of the terms "measurement error" and "correction", causing possible misinterpretation of these concepts when the intercomparison Protocol was used, this data were reviewed and corrected.


Documents

SIM.M.M-S14 MASS COMPARISON 200 mg, 1 g, 50 g, 200 g, 1 kg ...€¦ · Circulation of Draft A for comments/ editorial corrections May 2014 Final report. Draft B June 2014 4) Transfer