Steam Traps

1. Steam Traps Function and Types

2. Purpose • Steam traps exist to discharge air and condensate while not permitting the escape of live steam • Their goal is to ‘purify’ the steam of excess air and water (condensate) to : • Improve efficiency (Excess water or air in the system prevents it from reaching operating temperature quickly during start-up) • Protect system (Inadequate steam trapping can lead to waterhammer, corrosion, leakage, and high maintenance costs) • Provide maximum heat transfer (‘dry’ steam has best heat transfer properties in equipment like a heat exchanger)

3. Types • Mechanical steam traps - Have a float that rises and falls in relation to condensate level and this usually has a mechanical linkage attached that opens and closes the valve. Operate in direct relationship to condensate levels present in the body of the steam trap. Click link below to view mechanical steam trap with animation: [www.tlv.com/global/US/product-operation/free-float-steam-trap-jx.html]

4. Types • Temperature steam traps - Have a valve that moves in/out of position by either expansion/contraction caused by temperature change. Some condensate builds up as it cools sufficiently to allow the valve to open. In most circumstances this is not desirable as condensate needs to be removed as soon as it is formed. Click link below to view temperature steam trap with animation: [http://www.tlv.com/global/US/product-operation/temperature-control-steam-trap-lex.html]

5. Types • Thermodynamic steam traps - Work on the difference in response to velocity change in flow of compressible and incompressible fluids. As steam enters, static pressure above the disk forces the disk against the valve seat. The static pressure over a large area overcomes the high inlet pressure of the steam. As the steam starts to condense, the pressure against the disk lessens and the trap opens to allow condensate out. Click link below to view thermodynamic steam trap with animation: [http://www.tlv.com/global/US/product-operation/thermodynamic-steam-trap-a3n.html]

6. Comparison Temperature • intermittent operation • fair energy conservation • fair resistance to wear • good corrosion resistance • good abilities at low pressures • excellent operation against back pressure • good resistance to damage from freezing • excellent ability to handle start-up • fair ability to handle dirt • small comparative size • open or closed at mechanical failure (depending on design) Thermodynamic • intermittent operation • poor energy conservation • poor resistance to wear • excellent corrosion resistance • poor abilities at low pressures • poor operation against back pressure • good resistance to damage from freezing • excellent ability to purge system • poor ability to handle dirt • poor ability to handle flash steam • open at mechanical failure Mechanical • continuous operation • no action at no load, continuous at full load • good energy conservation • good resistance to wear • good corrosion resistance • excellent ability to vent air at very low pressure • excellent operation against back pressure • poor resistance to damage from freezing • fair ability to purge system • excellent performance on very light loads • poor ability to handle dirt • large comparative physical size • closed at mechanical failure