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--- articles:nist_traceability [2021/03/10 18:49] – [NIST Traceability Numbers - The Sasquatch of Metrology] rrandall
+++ articles:nist_traceability [2025/11/18 20:33] (current) – [An "unbroken chain of calibrations" to what?] rrandall
@@ Line 53: / Line 53: @@
 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>
+<WRAP info center round box 80%>On February 2, 2024, the U.S. FDA issued an [[https://www.federalregister.gov/documents/2024/02/02/2024-01709/medical-devices-quality-system-regulation-amendments|official ruling incorporating, by reference, the 2016 edition of ISO 13485]] (effective February 2, 2026). However, this incorporation does not change the requirements contained in Sec. 820.72(b)(1). Even if it did, ISO 13485:2016, sec. 7.6a also requires measuring equipment to be "calibrated or verified, or both, at specified intervals or prior to use, against measurement standards //traceable to international or national measurement standards...//".</WRAP>
 Similar antiquated language appears in [[http://everyspec.com/MIL-STD/MIL-STD-1300-1399/MIL-STD-1309D_87/|MIL-STD-1309D]], (12 February 1992), which doesn't even recognize international standards or offer alternatives where no national measurement standards exist:
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 I describe the above pyramid as "//typical//" because, contrary to the antiquated language of ISO 9001:2015 & AS9100:2016, it is possible to “bypass” the National Metrology Institutes (NMIs) to obtain traceability directly to SI units. Using the example of DC volts, [[https://www.fluke.com|Fluke]], a world leader in the field of metrology, owns a [[https://nvlpubs.nist.gov/nistpubs/jres/095/jresv95n3p219_A1b.pdf|Josephson voltage system]], which they can use to realize the SI Units directly.
-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 Measures" (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]].
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 </WRAP>
-SI Units are also explained on the NIST web site at: https://www.nist.gov/pml/weights-and-measures/metric-si/si-units and in "[[https://www.nist.gov/pml/special-publication-330|NIST Special Publication 330 -  The International System of Units (SI)]]". Both NIST sources will likely be updated soon to reflect the new definitions to the SI that went into effect on May 20, 2019.
+SI Units are also explained on the NIST web site at: https://www.nist.gov/pml/weights-and-measures/metric-si/si-units and in "[[https://www.nist.gov/pml/special-publication-330|NIST Special Publication 330 -  The International System of Units (SI)]]".
 ===== What are "intrinsic" standards? =====
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 Source: The "Bureau International des Poids et Mesures" (BIPM) [[https://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2012.pdf|JCGM 200:2012, "International vocabulary of metrology – Basic and general concepts and associated terms (VIM)"]] (3rd edition), sec. 5.2.
 </WRAP>
 I am aware of only four (4) "international standards" (as opposed to SI //units//); three of which are listed as examples in the definition shown above. However, there are probably others. Those that I am aware of include: \\
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 The only SI unit "physical artifact" (i.e., not defined by a fundamental, natural constant), the international prototype kilogram (IPK), was certified in 1889, and consists of a cylinder of platinum-iridium. The IPK is maintained by the [[https://www.bipm.org/en/publications/si-brochure/kilogram.html|BIPM]].
-<note>Because the IPKs stability has been a matter of significant concern, during November 2018, the world’s measurement experts voted and unanimously approved a revision of the SI that establishes a measurement system entirely based on physical constants of nature. The changes took effect on [[http://www.worldmetrologyday.org|World Metrology Day]], May 20, 2019; which commemorates the anniversary of the signing of the Metre Convention in 1875. See [[https://www.theverge.com/2018/11/13/18087002/kilogram-new-definition-kg-metric-unit-ipk-measurement|The Kilogram is Dead; Long Live the Kilogram]]</note>
+<WRAP center round info 80%>
+Because the IPKs stability has been a matter of significant concern, during November 2018, the world’s measurement experts voted and unanimously approved a revision of the SI that establishes a measurement system entirely based on physical constants of nature. The changes took effect on [[http://www.worldmetrologyday.org|World Metrology Day]], May 20, 2019; which commemorates the anniversary of the signing of the Metre Convention in 1875. See [[https://www.theverge.com/2018/11/13/18087002/kilogram-new-definition-kg-metric-unit-ipk-measurement|The Kilogram is Dead; Long Live the Kilogram]]
+</WRAP>
 **2 - Chorionic Gonadotrophin (Biological standard)** \\
 Defined by the [[http://apps.who.int/iris/bitstream/handle/10665/70154/WHO_BS_09.2107_eng.pdf|World Health Organization (WHO)]] in the 4th international standard 1999, as 75/589, 650 International Units per ampoule.