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| articles:nist_traceability [2021/11/10 06:49] – [What are SI Units?] rrandall | articles:nist_traceability [2023/02/01 18:32] (current) – [What are "International Standards"?] rrandall |
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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. | 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> | </WRAP> |
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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: \\ | 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: \\ |
| 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]]. | 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]]. |
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| <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]] |
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| **2 - Chorionic Gonadotrophin (Biological standard)** \\ | **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. | 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. |
