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Global coordination of Metrology and the CIPM MRA
The reliability of the international measurement system depends on work by each NMI to base its measurements and measurement uncertainties on the SI, and to compare its realizations of the base units of the SI with those of other NMIs. To establish such mutual equivalence, the NMIs will regularly participate in measurement comparisons. In order to extend and fully document the practice of comparisons and to provide objective evidence on which to base declarations of equivalence, in 1999 the CIPM launched a Mutual Recognition Arrangement (CIPM MRA) between NMIs from Member States of the Metre Convention and Associate States and Economies of the CGPM. The CIPM MRA establishes a formal system within which
NMI signatories and other designated institutes establish the degree of
equivalence of their national measurement standards via a peer-review
of their technical capabilities; as well as the mutual recognition of
their calibration and measurement certificates. This degree of equivalence
is technically supported through a series of 'key' measurement comparisons
which establishes a basis for comparing and linking measurements across
international boundaries.
The CIPM MRA commits metrology to provide an essential support for global trade through a mutual recognition framework, which can help eliminate technical barriers to trade and regulatory affairs. To support the CIPM MRA, the BIPM key comparison database (KCDB, which can be found at www.kcdb.org) provides free public access to the results of key comparisons and the peer-reviewed, SI traceable, calibration and measurement capabilities, and the degrees of equivalence of participating laboratories in many areas of chemistry and physics. The launch of the CIPM MRA was a major step for the Metre Convention. As a result, metrology laboratories are now more confident of the technical basis for their calibration services, and their listing provides NMIs with internationally recognized competence. It is already proving its value in the world of NMI metrology and a number of international and national organizations have already committed themselves to use it as evidence of technical equivalence at the highest levels, or for wider agreements negotiated for international trade, commerce or regulatory affairs. Whilst the technical coverage of the KCDB and the CIPM MRA is presently focused on physics, engineering and chemistry, the future will see related developments in the areas of laboratory medicine and food as the established framework can be applied to these new sectors. Already in laboratory medicine, the Joint Committee for Traceability in Laboratory Medicine (JCTLM) is creating a similar database of reference materials and processes. Key and other comparisons are underway to help provide the technical underpinning for this work. In this way, sound metrology practice will be applied to new activities, which contribute to human health and the quality of life. (For further details about the JCTLM, please see www.bipm.org/jctlm/) |
