ISO 1
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ISO 1is aninternational standardset by theInternational Organization for Standardizationthat specifies thestandard reference temperatureforgeometrical product specificationand verification. The temperature is fixed at 20degrees Celsius(°C), which exactly equals both 293.15kelvin(K) and 68degrees Fahrenheit(°F).[1]
Due tothermal expansion,precisionlengthmeasurements need to be made at (or converted to) a defined temperature. ISO 1 helps in comparing measurements by defining such a reference temperature. The reference temperature of 20 °C was adopted by theCIPMon 15 April 1931, and became ISO recommendation number 1 in 1951.[2]It soon replaced worldwide other reference temperatures for length measurements that manufacturers of precision equipment had used before, including 0 °C, 62 °F, and 25 °C. Among the reasons for choosing 20 °C was that this was a comfortable and practical workshop temperature and that it resulted in anintegervalue on both the Celsius and Fahrenheit scales.
It was the first ISO standard, issued originally asISO/R 1,aISO Recommendation.[3]
See also
References
- ^"ISO 1:2016 - Geometrical product specifications (GPS) -- Standard reference temperature for the specification of geometrical and dimensional properties".Iso.org. 2016-08-26.Retrieved2016-09-15.
- ^Ted Doiron:20 °C—A Short History of the Standard Reference Temperature for Industrial Dimensional MeasurementsArchived2013-02-17 at theWayback Machine.Journal of Research of the National Institute of Standards and Technology, Vol. 112, No. 1, January–February 2007.
- ^Tranchard, Sandrine (2017-02-23)."ISO celebrates 70 years".ISO.Retrieved2023-08-10.
