An introduction to steam traps that can help those working with them have a better understanding of how they work by David W. Fischer, PE, Senior Product Engineer Armstrong International, Inc., Three Rivers, MI Few, if any, colleges or universities offer courses on the use of steam as a means of transferring energy. Yet, most plant engineers are expected to understand an entire steam system, how it operates, and what will make it more efficient. Information can also be obtained from various professional associations, articles in professional journals, and trade publications. Other sources of knowledge are steam trap suppliers, industry competitors, and companies that use steam in their plants and processes. Some traps pass live steam at a controlled rate.
Most traps also pass air and other noncondensable gases while remaining closed to live steam.
To get the most heat out of a coil, heat exchanger, or other steam-using device, it is necessary to remove condensate as soon as it forms. It is also necessary to vent unavoidable, noncondensable gases to obtain the best possible heat transfer rates. Sometimes, as at startup, it is necessary to vent very large quantities of air. Steam pipes condense only a little steam, but they must be kept free of condensate to prevent potentially disastrous water hammer. The operating principle of each is the best way to differentiate the types of steam traps.