Transport Processes and Separation Process Principles (Includes Unit Operations) Fourth Edition

1.3. METHODS OF EXPRESSING TEMPERATURES AND COMPOSITIONS

1.3A. Temperature

There are two temperature scales in common use in the chemical and biological industries. These are degrees Fahrenheit (abbreviated °F) and Celsius (°C). It is often necessary to convert from one scale to the other. Both use the freezing point and boiling point of water at 1 atmosphere pressure as base points. Often temperatures are expressed as absolute degrees K (SI standard) or degrees Rankine (°R) instead of °C or °F. Table 1.3-1 shows the equivalences of the four temperature scales.

Table 1.3-1. Temperature Scales and Equivalents

	Centigrade	Fahrenheit	Kelvin	Rankine	Celsius
Boiling water	100°C	212°F	373.15 K	671.67°R	100°C
Melting ice	0°C	32°F	273.15 K	491.67°R	0°C
Absolute zero