Steam Trap Selection

When selecting a steam trap there are many points to consider to choose the appropriate trap. The below table is a good quick layout to help define which kind of steam trap would be more suitable to your application.

	Mechanical Trap		Thermodynamic Trap	Thermostatic Trap
	Float	Bucket	Disc	Bellows
Operating princlple	Difference in specific gravity between steam and condensate (up-and down movement due to buoyancy)		Difference in thermodynamic properties between steam and condensate	Difference in temperature between steam and condensate (Closed at steam temperature and opens at lower temperature)
Operating characteristics	Continuous	Intermittent	Intermittent	Continuous
Condensate accumulation	None	None	Possible	Possible
Steam loss amount	Negligible	Negligible	Small	Negligible
Discharge of air	Excellent	Fair	Excellent	Excellent
Water hammer proof	Fair	Excellent	Excellent	Poor
Back pressure tolerance	Excellent	Excellent	Poor(P2  must be 50% of P1  or less)	Fair
Response to load fluctuation	Immediate	Fair	Delayed	Delayed
Scale proof	Fair	Excellent	Poor	Fair
Size and weight	Large and heavy	Large and heavy	Small and light	Small and light
Installation posture	Limited*	Limited	Unlimited	Unlimited
Operation during failure (in many cases)	Closed	Open	Open	Closed
Application example	- Steam header, drain separator - Jacketed kettle· - Plate heat exchanger requring large condensate discharge and quick air-venting	- Steam header - Steam main pipe - Main pipe end where noise of water hammer must be avoided	- Steam main pipe end - ON-OFF controlled coil heater in boiling tank which has water hammer	- Heat exchanger without water hammer - Air conditioning unit with limited installation space