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 and sometimes indicated using this notation, see Réaumur scale and Rømer scale.
Rankine temperature conversion formulae
from Rankine to Rankine
Celsius [°C] = ([°R] − 491.67) × ​5⁄9 [°R] = ([°C] + 273.15) × ​9⁄5
Fahrenheit [°F] = [°R] − 459.67 [°R] = [°F] + 459.67
Kelvin [K] = [°R] × ​5⁄9 [°R] = [K] × ​9⁄5
For temperature intervals rather than specific temperatures,
1 °R = 1 °F = ​5⁄9 °C = ​5⁄9 K
Comparisons among various temperature scales

The Rankine scale (/ˈræŋkɪn/) is an absolute scale of thermodynamic temperature 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.)[1] It may be used in engineering systems where heat computations are done using degrees Fahrenheit.

The symbol for degrees Rankine is °R[2] (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with kelvin, some authors term the unit rankine, omitting the degree symbol.[3][4] Zero on both the Kelvin and Rankine scales is absolute zero, but a temperature difference of one Rankine degree is defined as equal to one Fahrenheit degree, rather than the Celsius degree used on the Kelvin scale. A temperature of −459.67 °F is exactly equal to 0 °R.

The US National Institute of Standards and Technology recommends against using the degree symbol when citing Rankine in NIST publications.[2]

Some important 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. ^ http://www.merriam-webster.com/dictionary/rankine
  2. ^ 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
  3. ^ Pauken, Michael (2011). Thermodynamics For Dummies. Indianapolis: Wiley Publishing Inc. p. 20. ISBN 978-1-118-00291-9. 
  4. ^ Balmer, Robert (2011). Modern Engineering Thermodynamics. Oxford: Elsevier Inc. p. 10. ISBN 978-0-12-374996-3. 
  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]


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