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Comparisons piloted by the BIPM

International comparisons take many forms. Some are carried out by the BIPM; others are organized by a Consultative Committee and may or may not include the BIPM; many more are organized and carried out, usually as part of the activities of a regional metrology organization, by the NMIs and other institutes participating in the CIPM MRA. Most BIPM comparisons are among the key comparisons chosen by the Consultative Committees to establish the degree of equivalence between national measurement standards.

For the comparisons carried out by the BIPM, the following procedures are used:

  • national standards are brought to the BIPM and compared with the BIPM standards, either individually or as a group, with similar standards from other national metrology institutes. The national standards may be either primary or secondary standards.

  • BIPM travelling primary standards are taken to a national metrology institute for comparison with those of that institute or, as increasingly happens, with standards from a group of national institutes from the same geographical region.

  • well-characterized BIPM travelling secondary standards are sent to a national metrology institute for comparison with the national standards of that institute.

This section lists the international comparisons piloted by the BIPM – mainly of the first type – many of which are ongoing BIPM key comparisons.

Resistance
  • BIPM.EM-K12: Quantum Hall resistance standards and their scaling to other resistance values (Resistance ratios: 100 ohms/RH(2), 10 kiloohms/100 ohms, and 100 ohms/1 ohm )
  • [Ongoing, approved for equivalence]
  • BIPM.EM-K13.a: Comparison of resistance standards (Resistance: 1 ohm)
  • [Ongoing, approved for equivalence]
  • BIPM.EM-K13.b: Comparison of resistance standards (Resistance: 10 kiloohms)
  • [Ongoing, approved for equivalence]

    DC Voltage and Current
  • BIPM.EM-K10.a: DC voltage, Josephson standards (DC voltage: 1.018 V)
  • [Ongoing, approved for equivalence]
  • BIPM.EM-K10.b: DC voltage, Josephson standards (DC voltage: 10 V)
  • [Ongoing, approved for equivalence]
  • BIPM.EM-K11.a: DC voltage, Zener diode (DC voltage: 1.018 V)
  • [Ongoing, approved for equivalence]
  • BIPM.EM-K11.b: DC voltage, Zener diode (DC voltage: 10 V)
  • [Ongoing, approved for equivalence]

    Capacitance
  • CCEM-K4.2017: Comparison of 10 pF capacitance standards
    Optional: comparison of 100 pF capacitance standards
    (Capacitance at 10 pF (optional capacitance at 100 pF))
  • [Protocol complete]
  • BIPM.EM-K14.a: Comparison of capacitors (Capacitance: 10 pF)
  • [Ongoing, approved for equivalence]
  • BIPM.EM-K14.b: Comparison of capacitors (Capacitance: 100 pF)
  • [Ongoing, approved for equivalence]
    Gases
  • BIPM.QM-K1: Ozone at ambient level (2007 -)
  • [Ongoing, approved for equivalence]
  • CCQM-K68.2019: Nitrous oxide in synthetic air (2019)
  • [Planned]
  • CCQM-K74: Nitrogen dioxide (NO2) in Nitrogen (N2) (2009 - 2010)
  • [Approved for equivalence]
  • CCQM-K74.2017: Nitrogen dioxide (NO2) in Nitrogen (N2) (2017)
  • [Planned]
  • CCQM-K82: Methane in air : preparative comparison (2012)
  • [Approved for equivalence]
  • CCQM-K90: Formaldehyde in Nitrogen (2015 - 2016)
  • [Report in progress, Draft B]
  • CCQM-K120: Ambient CO2 (2016)
  • [Planned]
  • CCQM-K137: NO in Nitrogen (2017 - 2018)
  • [Protocol complete]

    CCQM Pilot Studies [Organics]
  • CCQM-P20.e: Purity analysis series – Theophylline (2006)
  • [Approved and published]
  • CCQM-P20.f: Purity analysis series – Digoxin (2007)
  • [Approved and published]

    Organics
  • CCQM-K55.a: Purity assessment of high purity organic materials: 17beta-Estradiol (2008 - 2009)
  • [Approved for equivalence]
  • CCQM-K55.b: Purity assessment of high purity organic materials: aldrin (2010 - 2011)
  • [Approved for equivalence]
  • CCQM-K55.c: Purity assessment of high purity organic materials: L-(+)-Valine (2012)
  • [Approved for equivalence]
  • CCQM-K55.d: Mass fraction assignment of Folic acid in a high purity material (2015 - 2016)
  • [Report in progress, Draft A]
  • CCQM-K78.a: Mass fraction assignment of organic analytes in a multi-component aqueous calibration solution (2016 - 2017)
  • [In progress]
  • CCQM-K148.a: Mass fraction assignment of Bisphenol-A high purity material (2018)
  • [Planned]
  • CCQM-K115: Peptide purity determination - synthetic human C peptide (HCP) (2014)
  • [In progress]
    Section I (x and gamma rays, electrons)
  • BIPM.RI(I)-K1: Measurement of air kerma for Cobalt 60
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K2: Measurement of air kerma for low energy X rays
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K3: Measurement of air kerma for medium energy X rays
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K4: Measurement of absorbed dose to water for Cobalt 60
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K5: Measurement of air kerma for Caesium 137
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K6: Measurement of absorbed dose to water for high-energy photon beams
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K7: Measurement of air kerma in mammography beams
  • [Ongoing, approved for equivalence]
  • BIPM.RI(I)-K8: Measurement of reference air kerma rate for HDR Ir-192 brachytherapy sources
  • [Ongoing, approved for equivalence]

    Section II (Measurement of Radionuclides)
  • BIPM.RI(II)-K4.C-11: Activity of radionuclide C-11
  • [Ongoing]
  • BIPM.RI(II)-K1.Ag-110m: Activity of radionuclide Ag-110m
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ag-111: Activity of radionuclide Ag-111
  • [Ongoing]
  • BIPM.RI(II)-K1.Am-241: Activity of radionuclide Am-241
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Am-243: Activity of radionuclide Am-243
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Au-195: Activity of radionuclide Au-195
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ba-133: Activity of radionuclide Ba-133
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ba-140: Activity of radionuclide Ba-140
  • [Ongoing]
  • BIPM.RI(II)-K1.Bi-207: Activity of radionuclide Bi-207
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.C-11: Activity of radionuclide C-11
  • [Ongoing]
  • BIPM.RI(II)-K1.Cd-109: Activity of radionuclide Cd-109
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ce-139: Activity of radionuclide Ce-139
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ce-141: Activity of radionuclide Ce-141
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ce-144: Activity of radionuclide Ce-144
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Co-56: Activity of radionuclide Co-56
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Co-57: Activity of radionuclide Co-57
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Co-58: Activity of radionuclide Co-58
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Co-60: Activity of radionuclide Co-60
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Cr-51: Activity of radionuclide Cr-51
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Cs-134: Activity of radionuclide Cs-134
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Cs-137: Activity of radionuclide Cs-137
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Cu-64: Activity of radionuclide Cu-64
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Eu-152: Activity of radionuclide Eu-152
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Eu-154: Activity of radionuclide Eu-154
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Eu-155: Activity of radionuclide Eu-155
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.F-18: Activity of radionuclide F-18
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Fe-59: Activity of radionuclide Fe-59
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ga-67: Activity of radionuclide Ga-67
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Gd-153: Activity of radionuclide Gd-153
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ge-68: Activity of radionuclide Ge-68
  • [Ongoing]
  • BIPM.RI(II)-K1.Hg-203: Activity of radionuclide Hg-203
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ho-166m: Activity of radionuclide Ho-166m
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.I-123: Activity of radionuclide I-123
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.I-125: Activity of radionuclide I-125
  • [Ongoing]
  • BIPM.RI(II)-K1.I-131: Activity of radionuclide I-131
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.In-111: Activity of radionuclide In-111
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ir-192: Activity of radionuclide Ir-192
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Kr-85: Activity of radionuclide Kr-85
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Lu-177: Activity of radionuclide Lu-177
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Mn-54: Activity of radionuclide Mn-54
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Mn-56: Activity of radionuclide Mn-56
  • [Ongoing]
  • BIPM.RI(II)-K1.Mo-99: Activity of radionuclide Mo-99
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Na-22: Activity of radionuclide Na-22
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Na-24: Activity of radionuclide Na-24
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Nb-95: Activity of radionuclide Nb-95
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Np-237: Activity of radionuclide Np-237
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Pb-203: Activity of radionuclide Pb-203
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ra-223: Activity of radionuclide Ra-223
  • [Ongoing]
  • BIPM.RI(II)-K1.Re-186: Activity of radionuclide Re-186
  • [Ongoing]
  • BIPM.RI(II)-K1.Rn-222: Activity of radionuclide Rn-222
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ru-103: Activity of radionuclide Ru-103
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ru-106: Activity of radionuclide Ru-106
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Sb-124: Activity of radionuclide Sb-124
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Sb-125: Activity of radionuclide Sb-125
  • [Ongoing]
  • BIPM.RI(II)-K1.Sc-46: Activity of radionuclide Sc-46
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Sc-47: Activity of radionuclide Sc-47
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Se-75: Activity of radionuclide Se-75
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Sm-153: Activity of radionuclide Sm-153
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Sn-113: Activity of radionuclide Sn-113
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Sr-85: Activity of radionuclide Sr-85
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Ta-182: Activity of radionuclide Ta-182
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Tc-99m: Activity of radionuclide Tc-99m
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Th-228: Activity of radionuclide Th-228
  • [Ongoing]
  • BIPM.RI(II)-K1.Tl-201: Activity of radionuclide Tl-201
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Xe-133: Activity of radionuclide Xe-133
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Y-88: Activity of radionuclide Y-88
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Y-90: Activity of radionuclide Y-90
  • [Ongoing]
  • BIPM.RI(II)-K1.Yb-169: Activity of radionuclide Yb-169
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K1.Zn-65: Activity of radionuclide Zn-65
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K4.Cu-64: Activity of radionuclide Cu-64
  • [Planned]
  • BIPM.RI(II)-K4.F-18: Activity of radionuclide F-18
  • [Ongoing, approved for equivalence]
  • BIPM.RI(II)-K4.Tc-99m: Activity of radionuclide Tc-99m
  • [Ongoing, approved for equivalence]
    Traceability to the SI through the BIPM
    Subject area:
    What is traceability?
    BIPM policy on stating uncertainties
    Summary charts: Technical services per Member State
    Chemistry
    Electricity
    Ionizing Radiation
    Mass
    Time
    Related articles:
    BIPM calibration and measurement services
    BIPM work programme
    Joint BIPM, OIML, ILAC and ISO declaration on metrological traceability