'Rankine' is a
thermodynamic (absolute) temperature scale named after the
Scottish engineer and
physicist William John Macquorn Rankine, who proposed it in
1859.
The symbol is '°R' (or '°Ra' if necessary to distinguish it from the
Rømer and
Réaumur scales). As with the
Kelvin scale (symbol: K), zero on the Rankine scale 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 negative -459.67 °F is precisely equal to 0 °R.
Many engineering fields in the
U.S. measure thermodynamic temperature using the Rankine scale. However, throughout the scientific world where measurements are made in
SI units, thermodynamic temperature is measured in
Kelvin.
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 |
| Melting point of ice[1] | 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 | |
| Boiling point of water[2] | 373.1339 K | 99.9839 °C | 211.9710 °F | 671.641 °R |
References
1. The ice point of purified water has been measured to be 0.000089(10) degrees Celsius - see Reproducibility of the Temperature of the Ice Point in Routine Measurements, , B.W., Magnum, Nist Technical Note, 1995
2. 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.
See also
★
Comparison of temperature scales
★
Rankine-Hugoniot equation
External links