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. Japan has registered 1134 CMCs, which is ranked 6th in the world (Table 1).

Table 1. The number of registered CMCs of 10 major countries

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

	Country	Acoustics, Ultrasound and Vibration	Mass and Related Quantities	Length	Photometry and Radiometry	Thermo- metry	Time and Frequency	Electricity and Magnetism	Ionizing Radiation	Chemistry	Total
		AUV	M	L	PR	T	TF	EM	RI	QM
1	China	56	103	82	68	58	34	202	195	1018	1816
2	Russia	72	72	26	152	143	36	306	329	667	1803
3	Germany	52	190	102	95	117	25	174	266	462	1483
4	United States	31	107	49	114	85	11	321	531	213	1462
5	Korea	56	49	40	54	72	29	100	214	571	1185
6	Japan (NMIJ)*	8 (8)	104 (104)	32 (32)	57 (57)	52 (52)	29 (18)	58 (50)	259 (259)	535 (492)	1134 (1072)
7	United Kingdom	11	50	55	136	63	12	167	180	317	991
8	France	65	104	27	30	100	19	136	291	127	899
9	Mexico	40	112	34	22	11	9	149	55	330	762
10	Netherlands	0	85	72	28	70	26	207	23	244	755

Total by Metrology Area	AUV	M	L	PR	T	TF	EM	RI	QM	Grand Total
	1299	2938	1707	1535	2926	810	4610	3795	6097	25717

*The figures in the brackets show the number of NMIJ's registration.

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 (Table 2).

Table 2. The number of participation in the international comparisons

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

	Country	May 2011	Apr. 2012	May 2013	May 2014	Nov. 2015	Dec. 2016	Aug. 2017	Feb. 2018	Mar. 2019	Oct. 2020	Oct. 2021	Apr. 2022
1	Germany	547	575	600	627	683	698	719	730	753	612	791	798
2	Japan (NMIJ)*	361 (353)	390 (381)	407 (396)	427 (420)	462	476 (450)	491	496 (485)	508 (501)	538 (526)	555 (533)	563 (545)
3	United States	400	417	432	450	481	485	501	505	515	527	543	543
4	United Kingdom	403	422	432	448	478	479	488	492	502	523	538	542
5	France	369	389	406	430	451	465	475	483	496	521	534	539
6	Russia	301	322	340	360	392	408	422	431	450	471	507	515
7	Korea	303	332	354	378	395	410	423	428	450	479	498	501
8	China	253	277	302	323	352	366	381	387	410	456	477	486
9	Italy	244	257	272	282	293	299	302	308	316	329	338	341
10	Australia	233	249	257	269	281	286	299	301	307	319	332	334

Grand Total** of International Comparisons	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022
	1003	1081	1188	1278	1343	1453	1499	1529	1588	1673	1745	1767

*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.