Rankine scale

The Rankine scale (Template:IPAc-en Template:Respell) is an absolute scale of thermodynamic temperature named after the University of Glasgow engineer and physicist Macquorn Rankine, who proposed it in 1859.

History

Similar to the Kelvin scale, which was first proposed in 1848, 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 = Template:Sfrac °Ra or 1 K = 1.8 °Ra. A temperature of 0 K (−273.15 °C; −459.67 °F) is equal to 0 °Ra.

Usage

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

The symbol for degrees Rankine is °R. However, historical texts referring to "°R" are much more likely to mean the historically quite common Réaumur scale. As there is also the Rømer scale, it is better to use °Ra to be unambiguous. By analogy with the SI unit kelvin, some authors term the unit Rankine, omitting the degree symbol.

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 brineTemplate:Efn	255.37 K	459.67 °Ra	0 °F	−17.78 °C	−14.224 °Ré
	Freezing point of waterTemplate:Efn	273.15 K	491.67 °Ra	32 °F	0 °C	0 °Ré
	Boiling point of waterTemplate:Efn	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