Comparative Analysis on the Implementation of Est.
Comparative Analysis on the Implementation of Est.
Sílvio Francisco dos. SANTOS,
Scientific and Industrial Metrology Directorate
In October 1999, the directors of the National Metrology Institutes (NMIs) of thirty-eight
Member States of the International Bureau of Weights and Measures (BIPM), an organization set
up by the Metre Convention, and representatives of two international organizations, signed the
International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement
(MRA) [] for national measurement standards and for
calibration and measurement certificates issued by NMIs.

In October 2003, the National Institute of Standards and Technology (NIST), and in 2004, the
National Institute of Metrology, Standardization and Industrial Quality (INMETRO),
implemented an institution-wide quality system for the measurement services in response to the
requirements of section 7.3 of the CIPM MRA. The objectives of the MRA are to establish the
degree of equivalence of national measurement standards maintained by NMIs, and to provide for
the mutual acceptance of calibration and measurement certificates issued by NMIs. These
objectives provide governments and other parties with a secure technical foundation for wider
agreements related to international trade, commerce and regulatory affairs.

The process for implementing the CIPM MRA calls for international comparisons of
measurements, use of acceptable quality systems and practices, and demonstrations of
competence by the NMIs. The process of demonstrating the competence of an NMI also includes
the review of its quality system by the NMIs Regional Metrology Organization (RMO). NIST
and INMETRO are members of SIM, the Sistema Interamericano de Metrología (Spanish for
Interamerican Metrology System), [] which is the
RMO that covers the geographic region of the Americas.