Rankine scale

This article is about the temperature scale. For the idealized thermodynamic cycle for a steam engine, see Rankine cycle. For the scale measuring recovery after stroke, see Modified Rankin Scale.

Rankine
Unit of	Temperature
Symbol	R, °R, °Ra
Named after	Macquorn Rankine
Conversions
491.67 R in ...	... is equal to ...
Kelvin scale	273.15 K
Celsius scale	0 °C
Fahrenheit	32 °F

The Rankine scale ( /ˈræŋkɪn/ RANG-kin) is an absolute scale of thermodynamic temperature named after the University of Glasgow engineer and physicist Macquorn Rankine, who proposed it in 1859. ^[1] Similar to the Kelvin scale, which was first proposed in 1848, ^[1] zero on the Rankine scale is absolute zero, but a temperature difference of one Rankine degree (°R or °Ra) is defined as equal to one Fahrenheit degree, rather than the Celsius degree used on the Kelvin scale. In converting from kelvin to degrees Rankine, 1 K = ⁠9/5⁠ °R or 1 K = 1.8 °R. A temperature of 0 K (−273.15 °C; −459.67 °F) is equal to 0 °R. ^[2]

Usage

The Rankine scale is used in engineering systems where heat computations are done using degrees Fahrenheit. ^[3]

The symbol for degrees Rankine is °R ^[2] (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with the SI unit kelvin, some authors term the unit Rankine, omitting the degree symbol. ^{[4] [5]}

Some temperatures relating the Rankine scale to other temperature scales are shown in the table below.

		Scale
		Kelvin	Rankine	Fahrenheit	Celsius	Réaumur
Temperature	Absolute zero	0 K	0 °Ra	−459.67 °F	−273.15 °C	−218.52 °Ré
	Freezing point of brine [a]	255.37 K	459.67 °Ra	0 °F	−17.78 °C	−14.224 °Ré
	Freezing point of water [b]	273.15 K	491.67 °Ra	32 °F	0 °C	0 °Ré
	Boiling point of water [c]	373.1339 K	671.64102 °Ra	211.97102 °F	99.9839 °C	79.98712 °Ré

See also

• Outline of metrology and measurement
• Comparison of temperature scales

Notes

1. The freezing point of brine is the zero point of Fahrenheit scale, old definition, see: Grigull 1986
2. The ice point of purified water has been measured to be 0.000089(10) degrees Celsius – see Magnum 1995
3. For Vienna Standard Mean Ocean Water at one standard atmosphere (101.325 kPa) when calibrated solely per the two-point definition of thermodynamic temperature. Older definitions of the Celsius scale once defined the boiling point of water under one standard atmosphere as being precisely 100 °C. However, the current definition results in a boiling point that is actually 16.1 mK less. For more about the actual boiling point of water, see VSMOW in temperature measurement.

References

1. "Rankine". Merriam-Webster.com Dictionary . Merriam-Webster. Retrieved 2019-11-07.
2. B.8 Factors for Units Listed Alphabetically from Thompson & Taylor 2008 , pp. 45–69
3. Berger, Eric (2022-08-29). "Warning sign? NASA never finished a fueling test before today's SLS launch attempt". Ars Technica.
4. Pauken 2011 , p. 20
5. Balmer 2011 , p. 10

Bibliography

• Balmer, Robert (2011). Modern Engineering Thermodynamics. Oxford: Elsevier Inc. ISBN   978-0-12-374996-3.
• Magnum, B.W. (June 1995). "Reproducibility of the Temperature of the Ice Point in Routine Measurements" (PDF). NIST Technical Note. 1411. Archived from the original (PDF) on 2007-03-07. Retrieved 2007-02-11.
• Pauken, Michael (2011). Thermodynamics For Dummies. Indianapolis: Wiley Publishing Inc. ISBN   978-1-118-00291-9.
• Thompson, Ambler; Taylor, Barry N. (2008). "Guide for the use of the International System of Units (SI)" (PDF). NIST Special Publication. 811. doi:10.6028/nist.sp.811e2008 . Retrieved 2019-11-07.
• Grigull, Ulrich (1986). Heat Transfer (PDF). Retrieved 2022-08-29.