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articles:nist_traceability [2020/01/23 10:16] – [Conclusion] rrandallarticles:nist_traceability [2020/06/07 17:20] – [An "unbroken chain of calibrations" to what?] rrandall
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 Sec. 820.72 Inspection, measuring, and test equipment. \\ Sec. 820.72 Inspection, measuring, and test equipment. \\
 (b) (1) Calibration standards. Calibration standards used for inspection, measuring, and test equipment shall be __traceable to national or international standards__. If national or international standards are not practical or available, the manufacturer shall use an independent reproducible standard. If no applicable standard exists, the manufacturer shall establish and maintain an in-house standard.</WRAP> (b) (1) Calibration standards. Calibration standards used for inspection, measuring, and test equipment shall be __traceable to national or international standards__. If national or international standards are not practical or available, the manufacturer shall use an independent reproducible standard. If no applicable standard exists, the manufacturer shall establish and maintain an in-house standard.</WRAP>
 +
 +Similar antiquated language appears in MIL-STD-1309D, (12 February 1992), which doesn't even recognize international standards or offer alternatives where no national measurement standards exist:
 +<WRAP center round box 80%>**MIL-STD-1309D, "Definitions of Terms for Testing, Measurement and Diagnostics"**\\
 +3.1.653 Traceability. The ability to relate individual measurement results to __national standards or nationally accepted measurement systems__ through an unbroken chain of comparisons.
 +</WRAP>
  
 In contrast, ISO 17025:2017 is much more modern and technically correct in stating:\\ In contrast, ISO 17025:2017 is much more modern and technically correct in stating:\\
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 Also, while not strictly speaking a National Metrology Institute (NMI), the [[https://www.bipm.org|"Bureau International des Poids et Mesures" (BIPM)]] offers [[https://www.bipm.org/en/bipm-services/|calibration & Measurement services]] (with traceability to SI Units) to its [[https://www.bipm.org/en/about-us/member-states/|Member States]]. In that instance, the BIPM would serve as equivalent to a NMI. Also, while not strictly speaking a National Metrology Institute (NMI), the [[https://www.bipm.org|"Bureau International des Poids et Mesures" (BIPM)]] offers [[https://www.bipm.org/en/bipm-services/|calibration & Measurement services]] (with traceability to SI Units) to its [[https://www.bipm.org/en/about-us/member-states/|Member States]]. In that instance, the BIPM would serve as equivalent to a NMI.
 +
 +Transcat has an excellent White Paper on this topic at: [[https://www.transcat.com/calibration-resources/white-papers/what-is-measurement-traceability]].
 ===== What are SI Units? ===== ===== What are SI Units? =====
 {{ :articles:2018-si.png?direct&130|}} {{ :articles:2018-si.png?direct&130|}}