CIPM Mutual Recognition Arrangement

In response to economic globalization, the Mutual Recognition Arrangement (MRA) was drawn up by the International Committee of Weights and Measures (CIPM), under the authority given to it in the Metre Convention. The CIPM MRA was signed in 1999 at the 21st meeting of the General Conference on Weights and Measures (CGPM) by the National Metrology Institutes (NMIs) from 38 Member States of the Metre Convention and two international organizations. The arrangement was enforced in Jan. 2005. As of Jan. 2021, the arrangement covers institutes from 63 Member States, 39 Associate States and Economies of the CGPM and four international organizations. The list of participants is available at https://www.bipm.org/en/cipm-mra/participation.

The objectives of the CIPM MRA is to establish the degree of equivalence of national measruement standards maintained by NMIs and to provide for the mutual recognition of calibration and measurement certificates, thereby to provide governments and other parties with a secure technical foundation for wider agreements related to international trade, commerce and regulatory affairs.

Calibration Measurement Capabilities (CMCs)

To achieve the goal of the CIPM MRA mentioned above, NMIs and Designated Institutes (DIs) in individual countries develop and maintain their national measurement standards and declare their CMCs by establishing quality systems, receiving peer reviews by signatory NMIs and DIs, and participating in the related international comparisons for each each measurand. Approved CMCs are registered in the database (KCDB Appendix-C) maintained by the International Bureau of Weights and Measures (BIPM), and are publicly available on the Web. The total number of registered CMCs is 25717 as of April 2022.

KCDB searching system: https://www.bipm.org/kcdb/

International Comparison

The results of the international comparisons provide vital evidence for NMIs and DIs to declare their CMCs. Consultative Committees, set up for each metrology field under the CIPM, execute CIPM key comparisons to test the principal techniques and method of the field. In principle, these comparisons are conducted by the institutes having the highest technical competence and experience, normally by the member NMIs and DIs of the CCs. When a Regional Metrology Organization (RMO) conducts key comparisons, one of the institutes which participated in the preceding key comparison serve as the pilot institute in many cases. RMO key comparisons are open to all RMO members and other institutes, subject to decision by the organizing RMO.

The results of RMO key comparisons are linked to the corresponding CIPM key comparisons through the NMIs participated in the CIPM key comparisons, providing vital evidence to declare CMCs as well as the result of the CIPM key comparison. Meanwhile, supplementary comparisons are individually conducted by RMOs to cover areas or techniques not addressed by the CIPM and RMO key comparisons.

The results of international comparisons are registered in the database (KCDB Appendix-B) and updated on the Web. A total of 1767 international comparisons are registered in the KCDB as of April 2022. Japan is ranked 2nd in the world with participation in 563 international comparisons.

The number of participation in the international comparisons

(as of April 2022, KCDB searching system: https://www.bipm.org/kcdb/)

*The figures in the brackets show the number of NMIJ's participation in the international comparisons.

**The grand total shows the sum of key and supplementary comparisons registerd in the KCDB.