Archive for February, 2011

Closed Steel Expansion Tanks

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Closed Steel Expansion Tanks

The closed steel expansion tank has no moving parts (see Figure 10-43). It is normally two-thirds filled with water and one-third with air. As heated water expands and its excess volume enters the tank, it compresses the air at the top of the tank. The compression of the air in the tank results in an …

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Expansion Tanks

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Expansion Tanks

Expansion tanks (also sometimes called compression tanks) are installed in hydronic (hot-water) space heating systems to limit increases in pressure to the allowable working pressure of the equipment and to maintain minimum operating pressures. When the temperatures rise during the operation of the system, the water volume also increases and builds up pressure. The pressure …

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Boiler Return Traps

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Boiler Return Traps

A boiler return trap (or alternating receiver) is a device used in some vapor-steam heating systems to return condensation to the boiler under varying pressure conditions of operation up to the working limit of the boiler. A vapor-steam heating system in which a boiler return trap is used is sometimes referred to as a return-trap …

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Lifting Steam Traps

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Lifting Steam Traps

A lifting trap (see Figure 10-37) is an adaptation of the upright bucket trap and is available for pressures ranging from vacuum to 150 psig. Condensation in the chamber of the trap accumulates until it reaches a level high enough to cause the steam valve in the high pressure inlet to open. Steam then enters …

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Tilting Steam Traps

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Tilting Steam Traps

The operation of a tilting trap (see Figure 10-36) is intermittent in nature. With this type of trap, condensation enters a bowl and rises until its weight overbalances that of a counterweight, and the bowl sinks to the bottom. As the bowl sinks, a valve is opened, thus admitting live steam pressure on the surface …

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Impulse Steam Traps

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Impulse Steam Traps

An impulse trap (see Figure 10-35) operates with a moving valve actuated by a control cylinder. When the trap is handling condensation, the pressure required to lift the valve is greater than the reduced pressure in the control cylinder, and consequently the valve opens, allowing a free discharge of condensation. As the remaining condensation approaches …

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Flash Steam Traps

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Flash Steam Traps

A flash trap (see Figure 10-34) is used to drain condensation from steam lines; steam, water, and oil heaters; unit heaters; and other equipment in which the pressure differential between the steam supply and condensation return is 5 psig or more. The operation of a flash trap depends upon the property of condensation at a …

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Bucket Steam Traps

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Bucket Steam Traps

Bucket traps are either of the upright or inverted design and are used in both low- and high-pressure steam heating systems. Both types of bucket traps are designed to respond to the difference in density between steam and condensation. The construction of a bucket trap is such that it has good resistance to water hammer. …

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Thermodynamic Steam Traps

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Thermodynamic Steam Traps

A thermodynamic steam trap (see Figures 10-26 and 10-27) contains only one moving part, a hardened stainless-steel disc that functions as a valve. Because of its construction simplicity, this is an extremely rugged trap and is especially well suited for service on medium- and high-pressure steam lines operating under pressures up to 600 psig. The …

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Float and Thermostatic Traps

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Float and Thermostatic Traps

A float and thermostatic trap (see Figure 10-23) has both a thermostatic element to release air and a float element to release the condensation. As such, it combines features of both the float trap and the thermostatic trap. These traps are recommended for installations in which the volume of condensation is too large for an …

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