Rankine scale

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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.
"°R" redirects here. For other temperature scales sometimes indicated using this notation, see Réaumur scale and Rømer scale.
Rankine temperature conversion formulae
from Rankine to Rankine
Celsius [°C] = ([°R] − 491.67) × 59 [°R] = ([°C] + 273.15) × 95
Fahrenheit [°F] = [°R] − 459.67 [°R] = [°F] + 459.67
Kelvin [K] = [°R] × 59 [°R] = [K] × 95
For temperature intervals rather than specific temperatures,
1°R = 1°F = 59°C = 59 K
Comparisons among various temperature scales

Rankine (/ˈræŋkɪn/) is a thermodynamic (absolute) temperature scale named after the Glasgow University engineer and physicist William John Macquorn Rankine, who proposed it in 1859. (The Kelvin scale was first proposed in 1848.)

The symbol for degrees Rankine is °R[1] (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with Kelvin, some authors call the unit Rankine, omitting the degree symbol.[2][3] Zero on both the Kelvin and Rankine scales is absolute zero, but the Rankine degree is defined as equal to one degree Fahrenheit, rather than the one degree Celsius used by the Kelvin scale. A temperature of −459.67 °F is exactly equal to 0 °R.

Some engineering fields in the United States measure thermodynamic temperature using the Rankine scale.[4] The US National Institute of Standards and Technology recommends not using degrees Rankine in NIST publications.[1]

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

Kelvin Celsius Fahrenheit Rankine
Absolute zero
(by definition)
0 K −273.15 °C −459.67 °F 0 °R
Freezing point of brine
(by definition on Fahrenheit scale(only))
255.37 K −17.78 °C 0 °F 459.67 °R
Freezing point of water[5] 273.15 K 0 °C 32 °F 491.67 °R
Triple point of water
(by definition)
273.16 K 0.01 °C 32.018 °F 491.688 °R
Boiling point of water[6] 373.1339 K 99.9839 °C 211.97102 °F 671.64102 °R

Conversion table between the temperature units[edit]

Kelvin Celsius Fahrenheit Rankine scale Rømer scale Newton scale Delisle scale Réaumur scale

See also[edit]

Notes and references[edit]

  1. ^ a b B.8 Factors for Units Listed Alphabetically from Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 edition, Ambler Thompson and Barry N. Taylor
  2. ^ Pauken, Michael (2011). Thermodynamics For Dummies. Indianapolis: Wiley Publishing Inc. p. 20. ISBN 978-1-118-00291-9. 
  3. ^ Balmer, Robert (2011). Modern Engineering Thermodynamics. Oxford: Elsevier Inc. p. 10. ISBN 978-0-12-374996-3. 
  4. ^ http://www.physorg.com/tags/temperature/
  5. ^ The ice point of purified water has been measured to be 0.000089(10) degrees Celsius – see Magnum, B.W. (June 1995). "Reproducibility of the Temperature of the Ice Point in Routine Measurements" (PDF). Nist Technical Note 1411. Retrieved 2007-02-11. 
  6. ^ 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.

External links[edit]