ISO 1

ISO 1 is an

degrees Fahrenheit (°F).^[1]

Due to

CIPM on 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 an integer

value on both the Celsius and Fahrenheit scales.

It was the first ISO standard, issued originally as ISO/R 1, a

ISO Recommendation.^[3]

References

^ "ISO 1:2016 - Geometrical product specifications (GPS) -- Standard reference temperature for the specification of geometrical and dimensional properties". Iso.org. 2016-08-26. Retrieved 2016-09-15.
^ Ted Doiron: 20 °C—A Short History of the Standard Reference Temperature for Industrial Dimensional Measurements Archived 2013-02-17 at the Wayback 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. Retrieved 2023-08-10.

[1] "ISO 1:2016 - Geometrical product specifications (GPS) -- Standard reference temperature for the specification of geometrical and dimensional properties". Iso.org. 2016-08-26. Retrieved 2016-09-15.

[2] Ted Doiron: 20 °C—A Short History of the Standard Reference Temperature for Industrial Dimensional Measurements Archived 2013-02-17 at the Wayback Machine. Journal of Research of the National Institute of Standards and Technology, Vol. 112, No. 1, January–February 2007.

[Tranchard_2017_q168-3] Tranchard, Sandrine (2017-02-23). "ISO celebrates 70 years". ISO. Retrieved 2023-08-10.

[1]

[2]

[3]

See also

References