What Steam Tables Are…How to Use Them
The heat quantities and temperature/pressure relationships referred to on this page are taken from the Properties of Saturated Steam table.
How this Steam Table is Used
In addition to determining pressure/ temperature relationships, you can compute the amount of steam which will be condensed by any heating unit of known Btu output. Conversely, the table can be used to determine Btu output if steam condensing rate is known.
Definitions of Terms Used
Saturated Steam is pure steam at the temperature that corresponds to the boiling temperature of water at the existing pressure.
Absolute and Gauge Pressures Absolute pressure is pressure in pounds per square inch (psia) above a perfect vacuum. Gauge pressure is pressure in pounds per square inch above atmospheric pressure which is 14.7 pounds per square inch absolute. Gauge pressure (psig) plus 14.7 equals absolute pressure. Or, absolute pressure minus 14.7 equals gauge pressure.
Pressure/Temperature Relationship (Columns 1, 2 and 3). For every pressure of pure steam there is a corresponding temperature. Example: The temperature of 250 psig pure steam is always 406°F.
Heat of Saturated Liquid (Column 4). This is the amount of heat required to raise the temperature of a pound of water from 32°F to the boiling point at the pressure and temperature shown. It is expressed in British thermal units (Btu).
Latent Heat or Heat of Vaporization (Column 5). The amount of heat (expressed in Btu) required to change a pound of boiling water to a pound of steam. This same amount of heat is released when a pound of steam is condensed back into a pound of water. This heat quantity is different for every pressure/temperature combination, as shown in the steam table.
Total Heat of Steam (Column 6). The sum of the Heat of the Liquid (Column 4) and Latent Heat (Column 5) in Btu. It is the total heat in steam above 32°F.
Specific Volume of Liquid (Column 7). The volume per unit of mass in cubic feet per pound.
Specific Volume of Steam (Column 8). The volume per unit of mass in cubic feet