Thursday, October 8, 2015

The Steam Table, Terms and Heat Transfer Concepts

Steam Table, courtesy of
Armstrong International
(click image for larger view)
Here are some basic steam terms associated with the Steam Table (left). Below is a slideshow of basic heat transfer concepts.

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
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
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
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.

Total Heat of Steam
The sum of the Heat of the Liquid and Latent Heat in Btu. It is the total heat in steam above 32°F. Specific Volume of Liquid. The volume per unit of mass in cubic feet per pound.

Specific Volume of Steam
The volume per unit of mass in cubic feet per pound.

Basic Heat Transfer Concepts from Mead O'Brien, Inc.

For more information about any commercial or industrial steam or hot water systems, contact:

Mead O’Brien, Inc.
10800 Midwest Industrial Blvd
St. Louis, Missouri 63132
Phone (314) 423-5161
Toll Free (800) 874-9655
Fax (314) 423-5707