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Mutual recognition of national measurement standards...

   1   The arrangement

This is an arrangement between national metrology institutes which specifies terms for the mutual recognition of national measurement standards and for recognition of the validity of calibration and measurement certificates issued by national metrology institutes. It is drawn up by the CIPM with the authority given it under Article 10 (1921) of the Rules Annexed to the Metre Convention.


This arrangement is in two parts as specified in paragraph 2 below: part one concerns national measurement standards and part two concerns calibration and measurement certificates.


Participating national metrology institutes, signatories to this arrangement, may choose to limit their participation to part one, the recognition of national measurement standards.


Each signatory to this arrangement is the national metrology institute designated by the appropriate national governmental or other official authority of the Member State of the Metre Convention as being responsible for national measurement standards. For any state that has more than one such designated institute, the arrangement is signed by one institute on behalf of all, the names of the other institutes being attached to the document.


Designated NMIs of States or Economies that are Associates of the CGPM may participate in the arrangement only through their regional metrology organization by signing a declaration, appended to this arrangement.


Intergovernmental and international organizations designated by the CIPM may also participate in the arrangement.

   2   Scope of the arrangement

Participating national metrology institutes, listed in Appendix A, recognize the degree of equivalence of national measurement standards, derived from the results of key comparisons, for the quantities and values specified in Appendix B. This constitutes part one of the arrangement.


Participating institutes recognize the validity of calibration and measurement certificates issued by other participating institutes for the quantities and ranges specified in Appendix C. This constitutes part two of the arrangement.

   3   Technical basis of the arrangement

The technical basis of this arrangement is the set of results obtained in the course of time through key comparisons carried out by the Consultative Committees of the CIPM, the BIPM and the regional metrology organizations (RMOs), and published by the BIPM and maintained in the key comparison database. Detailed technical provisions are given in the Technical Supplement to this arrangement.


Key comparisons carried out by Consultative Committees or the BIPM are referred to as CIPM key comparisons; key comparisons carried out by regional metrology organizations are referred to as RMO key comparisons; RMO key comparisons must be linked to the corresponding CIPM key comparisons by means of joint participants. The degree of equivalence derived from an RMO key comparison has the same status as that derived from a CIPM key comparison.


A Joint Committee of the RMOs and the BIPM (the Joint Committee or JCRB), created by the CIPM, is responsible for the coordination of data provided by the RMOs, and other actions undertaken by them to promote confidence in calibration and measurement certificates (see paragraph 9.3).

   4   Responsibilities of the Consultative Committees of the CIPM

The Consultative Committees have the responsibility for choosing the key comparisons listed in Appendix D and affirming the validity of the results. The particular responsibilities of the Consultative Committees are detailed in the Technical Supplement.

   5   Responsibilities of the regional metrology organizations

The national metrology institutes that are signatories to this arrangement undertake to put in place appropriate structures within their RMOs so that the RMOs may:

  1. make proposals to the Consultative Committees on the choice of key comparisons;

  2. carry out the RMO key comparisons, described in the Technical Supplement, corresponding to the CIPM key comparisons;

  3. participate in the JCRB (see paragraphs 9.3 and 9.4 below);

  4. carry out supplementary comparisons and other actions designed to support mutual confidence in the validity of calibration and measurement certificates issued by participating institutes (see paragraph 7.3 below).
   6   Participation in key and supplementary comparisons

Participation in a CIPM key comparison is open to laboratories having the highest technical competence and experience, normally the member laboratories of the appropriate Consultative Committee. Those laboratories that are not members of a Consultative Committee and not NMIs must be nominated by the designated national metrology institute referred to in paragraph 1.4 as being responsible for the relevant national measurement standards. In choosing participants, the Consultative Committees should take proper account of regional representation. The number of laboratories participating in CIPM key comparisons may be restricted for technical reasons.


Participation in key comparisons organized by an RMO is open to all RMO members and to other institutes that meet the rules of the regional organization (including institutes invited from outside the region) and that have technical competence appropriate to the particular comparison.


Participation in RMO supplementary comparisons is open to those institutes meeting the requirements specified in paragraph 6.2.

   7   Confidence in measurements

Confidence in measurements is an essential prerequisite to international trade and facilitates almost every task in the industrialized world. To a large extent this confidence already exists and is based on the SI, which is the cornerstone of the international measurement system, as realized by the national metrology institutes. The function of this mutual recognition arrangement is to extend and consolidate pre-existing worldwide confidence in measurements.


Institutes participating in this arrangement are expected to extend existing international confidence in their activities by publishing regular reports on the work of their laboratories and transmitting them to the BIPM, by participation in relevant conferences, and by taking part in the activities organized by the BIPM.


In addition to participation in the key and supplementary comparisons, identified in paragraph 6, recognition of calibration and measurement certificates requires one of the following procedures in order to establish the necessary mutual confidence:

  1. an NMI that chooses for its calibration and measurement services a quality system that meets the requirements of ISO Guide 25 or equivalent for an NMI, assessed by an accreditation body fulfilling the requirements of ISO Guide 58, declares its calibration measurement capabilities (see paragraph T.7) and submits them to the local RMO for review and transmission to the Joint Committee for analysis and inclusion in Appendix C;

  2. an NMI that chooses to use a different way of assuring quality or chooses a different quality system, or ISO Guide 25 without third-party assessment, for its calibration and measurement services declares its calibration measurement capabilities (see paragraph T.7) and submits them to the local RMO for review and transmission to the Joint Committee for analysis and inclusion in Appendix C.
Demonstration of competence and capability may require visits and examination of procedures by an NMI and/or by peers selected by the local RMO.


Nothing in this arrangement is intended to limit the freedom of one or more signatories to establish mutual recognition, as specified in paragraphs 2.1 and 2.2, outside this arrangement.

   8   Disputes in the operation of the arrangement

This arrangement is operated by the BIPM in close consultation with the Consulative Committees and the RMOs whose responsibility it is, under paragraphs 4 and 5 above, to carry out and evaluate the results of the key comparisons. Disagreements that arise in the operation of this arrangement are discussed first within the appropriate Consultative Committee, the RMO or the Joint Committee and if not resolved there, are referred to the CIPM.

   9   Coordination

Overall coordination of activities related to this arrangement resides with the CIPM.


Coordination of the key comparisons is effected through consultations between the Consultative Committees and the RMOs.


Coordination of the supplementary comparisons and other actions related to confidence in calibration and measurement certificates undertaken by the regional metrology organizations is carried out by the JCRB. The JCRB is created by the CIPM comprising representatives of the RMOs and is chaired by the Director of the BIPM. Its terms of reference are given in Appendix E.


Under the overall responsibility of the CIPM, the Joint Committee is responsible for analysing and maintaining the content of Appendix C.

  10   Responsibility and liability for measurements

It is recognized and accepted by each signatory that this arrangement creates no rights, liabilities or obligations that will have binding effects in national or international law.


It is recognized and accepted by each signatory that this arrangement covers, in each country, only the signatory institute and other institutes represented by it. It does not necessarily extend to other metrological or regulatory bodies in that country.


Responsibility for all measurements made under this arrangement rests wholly with the institute making the measurements. No responsibility for declared uncertainties or statements of quality is assumed by the CIPM, the BIPM, the Consultative Committees or the RMOs.

  11   Signing this mutual recognition arrangement and bringing it into force

The procedure for implementing this arrangement is as follows:

  • at the meeting of directors of national metrology institutes held on 23-25 February 1998, the directors were invited to initial a draft of this arrangement;

  • at the meeting of directors of national metrology institutes to be held at the time of the 21st CGPM in October 1999, directors will be invited to sign this arrangement for an initial period of four years.
New signatories may attach themselves to this arrangement at any time by application to the Director of the BIPM.

To withdraw from the arrangement, the Director of a signatory institute should notify the Director of the BIPM six months prior to the effective date of withdrawal. The Director of the BIPM will notify all other signatories of such notice of withdrawal not later than one month after it has been received.


During the period from October 1999 until such time as the first round of key and supplementary comparisons has been completed and the quality systems specified in paragraph 7.3 put in place, the arrangement will operate in a transitional mode. Provisional degrees of equivalence (Appendix B) will be based on the results of comparisons carried out since about 1988, reviewed and approved by the Consultative Committee for each field and entered into the key comparison database referred to in paragraph 3.1. Provisional calibration and measurement capabilities (Appendix C) will be based on corresponding data reviewed by the RMOs and analysed by the JCRB, taking into account the procedures specified in paragraph 7.3 and included in the key comparison database.


After the initial period of four years, signatories may, with the approval of the appropriate governmental or other official authorities in their own country, make changes to this arrangement at meetings organized by the CIPM of directors of the national metrology institutes.

  12   Status of national measurement standards calibrated by the BIPM or by a national metrology institute

Nothing in this arrangement restricts the rights under the Metre Convention of participating national metrology institutes to have their national standards calibrated by the BIPM or by another national metrology institute. The mutual recognition of such standards depends upon subsequent participation in key or supplementary comparisons (see paragraphs 3 and 6 above).

  13   NMIs that are not members of an RMO

Those NMIs that wish to participate in this arrangement but are not members of an RMO, should either form a new RMO, or for the purposes of this arrangement, associate themselves with an existing RMO, whichever is the more appropriate. If neither approach is possible, they should seek to make special provisions.

  14   NMIs that are members of more than one RMO

Those NMIs that are members of more than one RMO must declare with which RMO they will participate in part two of this arrangement.

  15   Entry of new RMOs into the Joint Committee
The entry of a new RMO into the Joint Committee is subject to approval by the CIPM.