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Worldwide metrology

International trade and research relies on co-operation on measurement standards

A leader in international metrology since 1900

NPL provides advice and information to industry, regulators and academia on a range of international metrology issues. We liaise closely with other bodies that share similar issues (BSI, UKAS, Office of Product Safety and Standarisation) and provide services that benefit industry.

Metrology is the science of measurement and is key to international trade. Worldwide metrology at the highest level operates through a well-established network of National Metrology Institutes (NMIs) and Designated Institutes (DIs). As the UK's National Metrology Institute, we represent the UK both at a technical level and at the highest level of metrology in many international networks.

We also represent the UK on a number of international committees, organisations and arrangements, including the consultative committees of the Comité internationale des poids et mesures (CIPM), EURAMET (the European Association of National Metrology Institutes) and Versailles Project on Advanced Materials and Standards (VAMAS).

We are the UK signatory of the CIPM Mutual Recognition Arrangement, and our staff are active participants in a range of international bodies, including the European Society for Precision Engineering and Nanotechnology (euspen), International Measurement Confederation (IMEKO), NCSL International, and the International Congress of Metrology (CIM).

International standardisation and traceability

As a National Metrology Institute (NMI), the development of international standards for organisations such as the International Standards Organisation (ISO) is an essential component of our work.

Traceability is the property of a measurement or the value of a standard, which means it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons, all having stated uncertainties. Standards and traceability are important to ensure that measurements are comparable between laboratories, that data are defendable and meet the accreditation standards often required in industry.

Where nation-to-nation intercomparability or traceability to the SI units is required, then intercomparisons are conducted under the auspices of the CIPM's Consultative Committees or EURAMET's Technical Committees. The CIPM MRA (Mutual Recognition Arrangement) and CMCs (Calibration and Measurement Capabilities) provide the mechanism to ensure the equivalence of measurements in all of the participating countries.

The Metre Convention

The Metre Convention (Convention du Mètre) is the treaty that created the International Bureau of Weights and Measures (BIPM), an intergovernmental organisation under the authority of the General Conference on Weights and Measures (CGPM) and the supervision of the International Committee for Weights and Measures (CIPM).

The Convention was signed in Paris on 20 May 1875 by representatives of 17 nations, and co-ordinates international metrology and the development of the metric measurement system. The Convention, modified slightly in 1921, remains the basis of international agreement on units of measurement. Today, there are 61 Member States of the Metre Convention and 41 Associate States and Economies of the General Conference.

EURAMET – The European Association of National Metrology Institutes

EURAMET’s mission is to develop and disseminate an integrated, cost-effective and internationally-competitive measurement infrastructure for Europe, taking into account the needs of industry, business and governments. Bringing European NMIs and DIs together, the organisation supports members to meet their national requirements and to establish a balanced European measurement infrastructure. The main tool to achieve this goal is the European Metrology Programme for Innovation and Research (EMPIR), which has funded more than 200 joint research projects so far.

NPL is the UK member of EURAMET and an active participant in European research projects. The Management Support Unit, which manages the EMPIR funding programmes and their projects, is hosted at NPL.

The European Metrology Programme for Innovation and Research (EMPIR)

EMPIR projects with NPL involvement

Understanding international metrology

Bureau International des Poids et Mesures (BIPM) is an international organisation established by the Metre Convention with a role as the central coordinator for worldwide metrology.

The Comité international des poids et mesures (CIPM) is elected by the Member States of the Metre Convention to oversee the BIPM. The BIPM and CIPM guided the development of the international metrology system in operation today, the introduction of the SI system in 1960 and the establishment of the CIPM Mutual Recognition Arrangement in 1999. 

Regional Metrology Organisations (RMOs) are made up of NMIs from the same part of the world. RMOs coordinate activities between its members and also between other RMOs. The RMO for European NMIs is EURAMET and NPL is an active member of this organisation. NPL is also an Associate Member of the Asia-Pacific Metrology Programme, which is a reflection of its growing interests in that region.

EURAMET coordinates the cooperation of National Metrology Institutes (NMI) in Europe in fields such as research in metrology, traceability of measurements to the SI units, international recognition of national measurement standards and related Calibration and Measurement Capabilities (CMC).

International Laboratory Accreditation Cooperation (ILAC) is the international organisation for accreditation bodies operating in accordance with ISO/IEC 17011 and involved in the accreditation of conformity assessment bodies including calibration laboratories (using ISO/IEC 17025), testing laboratories (using ISO/IEC 17025), medical testing laboratories (using ISO 15189) and inspection bodies (using ISO/IEC 17020).

Accreditation is the independent evaluation of conformity assessment bodies against recognised standards to carry out specific activities to ensure their impartiality and competence. Through the application of national and international standards, government, procurers and consumers can have confidence in the calibration and test results, inspection reports and certifications provided. NPL is an accredited organisation to the United Kingdom Accreditation Service (UKAS) which is a signatory to the ILAC Mutual Recognition Agreement.

UKAS is the UK’s National Accreditation Body, responsible for determining, in the public interest, the technical competence and integrity of organisations such as those offering testing, calibration and certification services.

The British Standards Institute (BSI) is the UK's National Standards Body (NSB).

The International Organization for Standardisation (ISO) is an independent, non-governmental international body with a membership of 162 national standards bodies. BSI, as the UK's national standards body, is a member.

The International Organization of Legal Metrology (IOML) aims to put in place effective legal metrology infrastructures that are mutually compatible and internationally recognised and to facilitate trade, establish mutual confidence and harmonise the level of consumer protection worldwide.Legal metrology is the application of legal requirements to measurements and measuring instruments. 

WELMEC is a body set up to promote European cooperation in the field of legal metrology and develop and maintain mutual acceptance among its members. It maintains effective cooperation to achieve a harmonised and consistent approach to the societies needs for legal metrology and for the benefit of all stakeholders including consumers and businesses.

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