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