User Guide

Definitions
Saturated Steam is pure steam at the temperature
that corresponds to the boiling temperature of water
at the existing pressure.
Absolute and Gage Pressures. Absolute pressure
(psia) is pressure in pounds per square inch above a
perfect vacuum. Gage pressure is pressure in pounds
per square inch above atmospheric pressure which is
14.7 pounds per square inch absolute. Gage pressure
(psig) plus 14.7 equals absolute pressure. Or, absolute
pressure minus 14.7 equals gage pressure.
Pressure-Temperature Relationship (Columns 1, 2
and 3 on page 30.) For every pressure of pure steam
there is a corresponding temperature. Example:
Temper
ature of 250 psig pure steam always is 406°F.
Heat of Saturated Liquid (Column 4 on page 30.)
This is the amount of heat required to raise the tem-
perature of a pound of water from 32°F. to the boiling
point at the pressure shown. It is expressed in btu’s.
Latent Heat or Heat Ev
aporation.
(Column 5 on
page 30.) This is the amount of heat (expressed in
btu’s) 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 pres-
sure-temperature combination as shown in the steam
table.
Total Heat of Steam (Column 6 on page 30) is the
sum of the Heat of the Liquid (Column 4) and Latent
Heat (Column 5) in btu’s. It is the total heat in steam
above 32°F.
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