BIPM Key Comparison Research Articles

Force national standards comparison in the interamerican system of metrology (SIM), 100 kN compression

This force comparison was performed between IDIC (Chile), INTI (Argentina) and INM (Colombia), members of the SIM region. Each laboratory used its national standard for the established measuring range. The comparison started in August 2013 and finished in December 2013. This comparison has an overlap with the force steps used in the CIPM Key Comparison CCM.F-K2.a.1, at force points 50 kN and 100 kN.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparisons of national standards in the field of gas flow rate and volume, gas flow rates from 20 to 6500 m3/h

The supplementary international comparison of national gas flow standards COOMET.M.FF-S9 was carried out from May 2019 to January 2020. The comparison were made in the range of gas flow from 20 to 6500 m3/h. Six European National Metrological Institutes (VNIIM-VNIIR, PTB, IFSM, BelGIM, LEI and LABSAGAS) took part in the comparison. The VNIIM-VNIIR acted as a pilot laboratory. The participants used for comparison the reference test rigs, implemented mainly on the basis of reference critical nozzles or reference flow meters. The transportable comparison standards (rotary and turbine flow meters) were used for the comparison procedure and in sequence were sent to the participants for testing. According to the results of the comparison, all participants confirmed their calibration and measuring capabilities in the declared flow ranges.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison of the national standards of air kerma between the PTB and the CPHR for selected x-ray qualities used in radiation protection, diagnostic radiology and radiation therapy (COOMET.RI(I)-S4)

The air kerma calibration coefficients of a set of four transfer ionization chambers and the air kerma-length product calibration coefficients for a set of two transfer pencil-type ionization chambers were compared at the PTB, Germany, and the CPHR, Cuba, for 15 selected radiation qualities as used in mammography, general diagnostic radiology, computed tomography, radiation therapy and radiation protection. The CPHR performed its measurements in the period January to September 2017 and the PTB before (November 2016) and after (December 2017) that period. The comparison results for the selected beam qualities expressed as the ratio of calibration coefficients were in the range (0.98-1.01) and mostly (12 out of 18) consistent within the relative standard uncertainty of the comparison which ranged between 0.6 % and 1 %. Five results were within the extended (k=2) standard uncertainty. One result deviated relatively by 1.9%. A possible reason for the larger deviation is discussed. The results are published in the Key Comparison Data Base (KCDB) of the BIPM as supplementary comparison COOMET.RI(I)-S4.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Supplementary comparison COOMET.M.P-S4 of gas absolute pressure standards up to 7 MPa, and gauge up to 2 MPa

This report describes the results of a successful two-phase interlaboratory comparison between Georgian National Agency for Standards and Metrology (GeoSTM), Czech Metrology Institute (CMI) and Slovak Metrology Institute (SMU) denoted as COOMET.M.P-S4. The ranges of the absolute pressure from 0 MPa to 7 MPa and gauge pressure from 0 MPa to 2 MPa were chosen as the most suitable for a mutual comparison. A digital pressure gauge, DHI RPM4 served as a transfer standard in both phases. Firstly, bilateral interlaboratory comparison (BILC) between two participants, CMI (pilot and reference laboratory) and GeoSTM, started in March 2017 and finished in April 2017. Secondly, interlaboratory comparison (ILC) between three participants, CMI (pilot and reference laboratory), SMU (co-reference laboratory) and GeoSTM, started in October 2018 and finished in February 2019. SMU took part only in the absolute pressure comparison.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison of force standard machines in the range of 100 kN and 1000 kN

This report presents the results of a supplementary comparison of force standard machines organized by GULFMET and piloted by TÜBİTAK UME. This is the first such comparison organized in the Gulf region and was carried out in accordance with the procedures detailed in CIPM MRA-D-05 with the purpose of providing evidence for the metrological equivalence of participants in force realization in the ranges of 100 kN and 1000 kN. It can be surmised from the result evaluation that the participants' performance is satisfactory and the uncertainty values claimed by them have been validated.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Supplementary comparison EURAMET EM-S41 bilateral comparison of DC voltage reference standards (1,018 V and 10 V) (EURAMET.EM-S41)

This report describes a bilateral comparison of DC voltage standards organised within the frame of the EU-Indonesia Trade Support Program II n° APE12-06b between LNE, France and KIMLIPI, Indonesia. This bilateral comparison registered in the KCDB as EURAMET.EM-S41 was piloted by LNE. LNE participated in EUROMET comparison N° 429, designated EUROMET.EM.BIPM-K11 thus providing the link between KIM-LIPI results and CCEM-K11. This report includes the measurement results from the participants and information about their calibration methods for measurements of 1,018 V and 10 V.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on key comparison EURAMET.AUV.V-K2

This final report describes the results obtained in a key comparison of primary vibration calibration facilities. Two piezoelectric standard accelerometers (one single-ended as well one back-to-back type) were calibrated first at Central Office of Measures (GUM), acting as pilot and linking laboratory, and Bulgarian Institute for Metrology (BIM). The results of the BIM obtained in this comparison were linked to the CCAUV.V-K2 key comparison through the joint participation of the GUM. The degrees of equivalence were computed for BIM with respect to the CCAUV.V-K2 key comparison reference value.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

COOMET.T-S3: supplementary comparison on relative humidity (RH) from 30 % rh to 90 % rh at 23 °C

This report describes the results of supplementary comparison COOMET.T-S3 (also known as supplementary comparison COOMET 768/GE/18) on relative humidity (RH) from 30 % rh to 90 % rh at 23 °C. The comparison was organised between the National Physical Laboratory (NPL) United Kingdom (Laboratory-coordinator) and Georgian National Agency for Standards and Metrology (GEOSTM), Georgia. The comparison started in July 2018 and finished in September 2019The majority of the bilateral degree of equivalence values, DGEOSTM/NPL , for the two participants are low compared to the uncertainty in the DoE, UGEOSTM/NPL . With this comparison, the participant GEOSTM has demonstrated their technical competence for realization of relative humidity in the range 30 %rh to 90 %rh at 23 °CMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Results of the CCRI(II)-K2. H-3 key comparison 2018: measurement of the activity concentration of a tritiated-water source

A comparison of the activity concentration measurement of a 3H2O solution was organized by the LNE-LNHB under the auspices of the CCRI(II). The solution was sent to thirteen laboratories and eleven measurement reports were received. The results, as well as relevant information on the measurement techniques, are presented and analysed in this paper. All results are consistent within uncertainties. As the solution was traceable to the solution used in the CCRI(II)-K2.H-3 comparison in 2009, the results of both comparisons are also presented.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison BIPM.RI(I)-K6 of the standards for absorbed dose to water of the KRISS, Korea and the BIPM in accelerator photon beams

A key comparison has been made between the absorbed dose to water standards of the KRISS, Korea and the BIPM in accelerator photon beams. The results show the standards to be in agreement within the expanded uncertainty (k = 2) of the comparison of 12 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Report of APMP comparison of the activity measurements of Fe-59 (APMP.RI(II)-K2.Fe-59)

The international comparison of activity measurements of 59Fe, APMP.RI(II)-K2.Fe-59, was carried out within the framework of the Asia-Pacific Metrology Programme (APMP). Nine institutes took part in the comparison, and eight institutes of them undertook absolute measurements. One ampoule prepared using the same radioactive solution as that used in the comparison was sent to the BIPM/SIR in order to link the comparison to the BIPM key comparison reference value (KCRV).Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

EURAMET-T.K9.1 bilateral comparison of ITS-90 SPRT calibration from the Hg TP to Zn FP

Justervesenet (JV, Norway) and Metrosert (Estonia) agreed in 2016 to conduct a bilateral comparison of SPRT calibrations for the fixed points from the triple point of Hg to the freezing point of Zn, with the exception of the freezing point of In which Metrosert could not realise. The aim of the comparison was to link Metrosert to the CCT-K9 via the EURAMET-T.K9. JV was the linking laboratory to the EURAMET-T.K9 and the pilot. An SPRT was first calibrated at Metrosert, shipped to JV and calibrated there, and finally returned to Metrosert for a second calibration. The measurements were carried out and completed in 2017.The results show that the laboratories involved are in agreement. At the triple point of Hg and the melting point of Ga the results are consistent and agree at all three reported measurements. At the freezing points of Sn and Zn Metrosert observes some change in W-values, although the difference is smaller than the reported uncertainty. The difference may suggest some drift either in the circulating probe or in the reference equipment at Metrosert, and this discrepancy increased the uncertainty in the degree of equivalence somewhat.The resistance of the probe was measured at the triple point of water after every fixed point, and prior to and after annealing upon reception at the laboratories. In general the resistance values are stable, but may suggest some drift between the first measurements at Metrosert and the measurements at JV.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

High value resistance comparison (SIM.EM-S15)

This is a report of the results of an Interamerican Metrology System (SIM) comparison on high resistance values, performed to compare the measurement capabilities of National Institute of Standards and Technology (NIST) and (Instituto Costarrricense de Electricidad - Laboratorio Metrológico de Variables Eléctricas) ICE-LMVE and for establishing the degree of equivalence between those laboratories.During 2018, two resistance standards were used as traveling standards for measurements in those countries, with NIST-USA acting as the pilot laboratory. Results for four measurement points are presented as errors relative to a comparison reference value together with their uncertainty.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

BIPM comparison BIPM.RI(II)-K1.Fe-59 of activity measurements of the radionuclide 59Fe for the PTB (Germany), LNE-LNHB (France) and the NMIJ (Japan), and the linked APMP.RI(II)-K2.Fe-59 comparison

Three new participations in the BIPM.RI(II)-K1.Fe-59 comparison have been added to the previous results and this has produced a revised value for the key comparison reference value (KCRV), calculated using the power-moderated weighted mean. A link has been made to the APMP.RI(II)-K2.Fe-59 comparison held in 2014 through the NMIJ who participated in both comparisons. Five NMIs used the K1 or K2 comparison to update their degree of equivalence. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the remaining five NMIs in the BIPM.RI(II)-K1.Fe-59 comparison and the eight other participants in the APMP.RI(II)-K2.Fe-59 comparison. A graphical presentation is also given.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Supplementary comparison EURAMET.AUV.A-S2

The Supplementary comparison EURAMET.AUV.A-S2 has been carried out under the auspices of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) of the International Bureau of Weights and Measures (BIPM). This comparison is concerned with secondary free-field methods of microphone calibration, particularly the methods described in the International Standard IEC 61094-8 (2012). The participating NMI's are BEV (Austria), DFM (Denmark), INMETRO (Brazil), INRiM (Italy), LNE (France), NPL (UK) and PTB (Germany). The role of Pilot laboratory was undertaken by LNE (France). The measurements took place between February 2014 and June 2016. Two WS2 microphones were circulated. This report includes the measurement results from the participants, information about their calibration methods, and the analysis leading to the assignation of equivalence degrees.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison on calibration factor measurement of power sensor

This comparison covers the measurement of calibration factors (CF) of power sensors and was carried out where SASO NMCC and TUBITAK UME participated, on the frame of GULFMET.Calibration factors are used for characterization of RF power sensors. RF power sensors are used to measure RF power, and is an important mean to achieve traceability of RF power measurements. This bilateral comparison was performed by measuring a power sensor at frequencies of 10 MHz, 50 MHz, 1 GHz, 4 GHz, 8 GHz, 12 GHz, 15 GHz, and 18 GHz, at a power level of 0 dBm.TÜBİTAK UME was acting as the pilot laboratory. The travelling standard was provided by SASO NMCC. TUBITAK UME was responsible for monitoring standard performance during the circulation and the evaluation and reporting of the comparison results.The comparison was carried out in accordance with the CCEM Guidelines for Planning, Organizing, Conducting and Reporting Key, Supplementary and Pilot Comparisons.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CCQM-K137, nitrogen monoxide (NO) in nitrogen

The key comparison CCQM-K137 was aimed at evaluating the level of compatibility of laboratories' preparative capabilities for gravimetric nitrogen monoxide/nitrogen primary reference mixtures at mole fractions of 30 μmol mol-1 and 70 μmol mol-1.The comparison was organised by the BIPM. It consisted in the simultaneous comparison of a suite of 2n primary gas standards, two standards to be prepared by each of the n participating laboratories at the nominal values of 30 μmol mol-1 and 70 μmol mol-1. Two independent analytical methods were used by the BIPM to analyse the amount fraction of nitrogen monoxide (NO) in nitrogen; UV spectrophotometry and chemiluminescence (CLD). The agreement between the results obtained with the two main techniques served to highlight possible issues in the preparation of the standards. During this comparison, standards prepared by two participants appeared to result in a larger bias between the analysers than observed for others. These observations were explained by the analysis of all standards by Fourier Transform Infrared Spectroscopy (FTIR) which identified the presence of a larger amounts of water vapour (H2O), nitrous oxide (N2O) and nitrogen dioxide (NO2) in these standards, which are the three main impurities which can appear in mixtures of NO in nitrogen.The above observations were used to underpin the selection of standards (at each nominal NO mole fraction) which can be considered as a consistent set, allowing the calculation of a calibration line by a Generalised Least-Square regression. Key Comparison Reference Values were then proposed for all participants as predicted values from the calibration lines. Interferences caused in the response of the CLD analyser by impurities (verified by FTIR measurements) led to only the results from the UV analyser being proposed for the KCRV and Degrees of Equivalence calculations. Good agreement was observed between all participants who could prepare their standards with minimum levels of impurities.The key comparison CCQM-K137 is considered to present an analytical challenge at both nominal mole fractions and therefore considered as a Specialised (Track C) comparison in the CCQM nomenclature.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NPL, UK, and the BIPM in low-energy x-rays

A key comparison has been made between the air-kerma standards of the NPL, UK and the BIPM in the low-energy x-ray range. The results indicate a progressive drift of the NPL standard, now lower than the BIPM standard by around 1 part in 102. The expanded uncertainty (k = 2) of the comparison is 4.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NPL, UK, and the BIPM in medium-energy x-rays

A key comparison has been made between the air-kerma standards of the NPL, UK, and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.4 parts in 103, with some evidence of a dependence on radiation quality. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.KEY WORDS FOR SEARCHRadiation dosimetry, air kerma, comparison, medium-energy x-raysMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between the NIM (The People's Republic of China) and the BIPM

This report gives the result of a bilateral comparison of resistance between the NIM (The People's Republic of China) and the BIPM carried out at the end of 2018, beginning of 2019. Two 1 Ω and two 10 kΩ travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about one month, then for a period of one month at the NIM, and finally again at the BIPM. The measurand was the 4 terminal dc resistance at low power. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparisons BIPM.EM-K13.a (for 1 Ω) and BIPM.EM-K13.b (for 10 kΩ).The results from the NIM and the BIPM were found to be in good agreement, with a difference smaller than the relative expanded uncertainties (95% confidence, k = 2) for both 1 Ω and 10 kΩ standards. Relative differences are + 0.010 × 10−6 for 1 Ω and − 0.001 × 10−6 for 10 kΩ with a relative expanded uncertainty of 0.034 × 10−6 for 1 Ω and 0.032 × 10−6 for 10 kΩ.KEY WORDS FOR SEARCHResistance; ohm; NIM; The People's Republic of China; BIPM; CIPM MRA; comparison; K13; electricityMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).