Editing Metrology (section)

== National infrastructure ==
A national measurement system (NMS) is a network of laboratories, calibration facilities and accreditation bodies which implement and maintain a country's measurement infrastructure.<ref name="National Measurement System"/><ref name="NQI">{{cite web|title=The National Quality Infrastructure|url=https://innovationpolicyplatform.org/sites/default/files/rdf_imported_documents/TheNationalQualityInfrastructure.pdf|publisher=The Innovation Policy Platform|access-date=5 March 2017|url-status=live|archive-url=https://web.archive.org/web/20170306130935/https://innovationpolicyplatform.org/sites/default/files/rdf_imported_documents/TheNationalQualityInfrastructure.pdf|archive-date=6 March 2017}}</ref> The NMS sets measurement standards, ensuring the accuracy, consistency, comparability, and reliability of measurements made in the country.<ref>{{cite web|title=National Measurement System|url=https://nmckh.wordpress.com/about/national-measurement-system/|publisher=National Metrology Center (NMC)|access-date=5 March 2017|date=23 August 2013|url-status=dead|archive-url=https://web.archive.org/web/20170306033754/https://nmckh.wordpress.com/about/national-measurement-system/|archive-date=6 March 2017}}</ref> The measurements of member countries of the CIPM Mutual Recognition Arrangement (CIPM MRA), an agreement of national metrology institutes, are recognized by other member countries.<ref name=FCM/> As of March 2018, there are 102 signatories of the CIPM MRA, consisting of 58 member states, 40 associate states, and 4 international organizations.<ref>{{cite web|title=BIPM – signatories|url=https://www.bipm.org/en/cipm-mra/participation/signatories.html|website=www.bipm.org|publisher=Bureau International des Poids et Mesures|access-date=24 March 2018}}</ref>

=== {{anchor|National metrology institutes}}Metrology institutes ===
[[File:National Measurement System Overview.png|thumb|alt=Block diagram|Overview of a national measurement system]]
A national metrology institute's (NMI) role in a country's measurement system is to conduct scientific metrology, realise base units, and maintain primary national standards.<ref name=FCM/> An NMI provides traceability to international standards for a country, anchoring its national calibration hierarchy.<ref name=FCM/> For a national measurement system to be recognized internationally by the CIPM Mutual Recognition Arrangement, an NMI must participate in international comparisons of its measurement capabilities.<ref name="NQI"/> BIPM maintains a comparison database and a list of calibration and measurement capabilities (CMCs) of the countries participating in the CIPM MRA.<ref>{{cite web|title=The BIPM key comparison database|url=http://kcdb.bipm.org/|publisher=Bureau International des Poids et Mesures|access-date=5 March 2017|url-status=dead|archive-url=https://web.archive.org/web/20170129024102/http://kcdb.bipm.org/|archive-date=29 January 2017}}</ref> Not all countries have a centralised metrology institute; some have a lead NMI and several decentralised institutes specialising in specific national standards.<ref name=FCM/> Some examples of NMI's are the [[National Institute of Standards and Technology]] (NIST)<ref>{{cite journal|title=International Legal Organizational Primer|url=https://www.nist.gov/pml/weights-and-measures/international-legal-metrology/ilmp-organizational-primer|journal=NIST|access-date=25 March 2018|language=en|date=14 January 2010}}</ref> in the United States, the [[National Research Council (Canada)|National Research Council]] (NRC)<ref>{{cite web|title=Measurement science and standards – National Research Council Canada|url=https://www.nrc-cnrc.gc.ca/eng/rd/mss/index.html|publisher=National Research Council of Canada|access-date=25 March 2018|language=en}}</ref> in Canada, the [[Physikalisch-Technische Bundesanstalt]] (PTB) in Germany,<ref>{{cite web|title=PTB|url=https://www.ptb.de/cms/en/|publisher=PTB|access-date=18 June 2023|language=en}}</ref> and the [[National Physical Laboratory (United Kingdom)]] (NPL).<ref>{{cite web|title=Creating impact from science and engineering – National Physical Laboratory|url=http://www.npl.co.uk|publisher=National Physical Laboratory|access-date=25 January 2022|language=en|date=17 June 2017}}</ref>

=== Calibration laboratories ===
Calibration laboratories are generally responsible for calibrations of industrial instrumentation.<ref name="NQI"/> Calibration laboratories are accredited and provide calibration services to industry firms, which provides a traceability link back to the national metrology institute. Since the calibration laboratories are accredited, they give companies a traceability link to national metrology standards.<ref name=FCM/> 

=== Accreditation bodies ===
An organisation is accredited when an authoritative body determines, by assessing the organisation's personnel and management systems, that it is competent to provide its services.<ref name="NQI"/> For international recognition, a country's accreditation body must comply with international requirements and is generally the product of international and regional cooperation.<ref name="NQI"/> A laboratory is evaluated according to international standards such as [[ISO/IEC 17025]] general requirements for the competence of testing and calibration laboratories.<ref name=FCM/> To ensure objective and technically-credible accreditation, the bodies are independent of other national measurement system institutions.<ref name="NQI"/> The [[National Association of Testing Authorities]]<ref>{{cite web|title=NATA – About Us|url=http://www.nata.com.au/about-nata|publisher=NATA|access-date=25 March 2018|language=en-gb}}</ref> in Australia and the [[United Kingdom Accreditation Service]]<ref>{{cite web|title=About UKAS|url=https://www.ukas.com/about/|publisher=UKAS|access-date=25 March 2018|language=en}}</ref> are examples of accreditation bodies.