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--- articles:nist_traceability [2021/03/10 18:47] – [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 13: / Line 13: @@
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 **[[https://www.nist.gov/system/files/documents/2019/06/21/gmp-13-ensuring-traceability-20190621.pdf|NIST GMP 13, "Good Measurement Practice
-for Ensuring Metrological Traceability”]], sec. 1.6.3, "Use of, or reference to, official test numbers of a national metrology institute":** \\
+for Ensuring Metrological Traceability”]], sec. 1.6.3, "Use of, or reference to, official test numbers of a national metrology institute.":** \\
-"//Having an authentic test number does not provide assurance or evidence that the measurement value provided by another organization is traceable. Not only must there be an unbroken chain of comparisons, but each measurement must be accompanied by a statement of uncertainty associated with the value. Test report numbers should not be used nor required as proof of the adequacy or traceability of a test or measurement. National and international standards dealing with test and measurement quality requirements, such as ISO 10012, ISO/IEC 17025 and the ISO 9000 series do not require the use or reporting of specific test numbers to establish traceability.//"
+"//Having an authentic test number does not provide assurance or evidence that the measurement value provided by another organization is traceable. Not only must there be an unbroken chain of comparisons, but each measurement must be accompanied by a statement of uncertainty associated with the value. Test report numbers should not be used nor required as proof of the adequacy or traceability of a test or measurement. National and international documentary standards for test and measurement quality requirements, such as ISO 10012, ISO/IEC 17025 and the ISO 9000 series, provide guidance for assessing metrological traceability and do not require the use or reporting of specific test numbers to establish metrological traceability.//"
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 This is further noted in the:
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 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.
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 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>
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+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.