Operation / Characteristics / Hoffman Specialty Product
Features / Primary Applications
Thermostatic steam traps reduce start-up times and improve overall
Balanced Pressure Thermostatic Traps use a special bellows
diaphragm. The diaphragm is designed to open in response to pressure and temperature to
discharge air and condensate, and to close against passage of steam. The temperature at
which a Thermostatic Trap opens is variable, but is 10 to 30° F below saturated steam
temperature for the existing pressure.
This type of trap is small, simple in construction, size
and weight, and has adequate capacity for various applications, especially in low-pressure
Operation of Thermostatic Traps:
||Thermostatic traps are normally
open allowing fast venting of air during start-up.
||During start-up, cold condensate
drains through the trap. As temperatures reach 10° to 30° F of saturation, the
thermostatic bellows element closes the trap.
During operation, thermostatic traps find an equilibrium
point to drain condensate approximately 10° to 30° F below saturation at continuous
Characteristics of Thermostatic Traps:
- Sub-cools condensate usually 10° to 30° F.
- Normally open at start-up to provide fast air venting.
- Follows steam saturation curve to operate over wide range of
- Energy efficient.
- Fast response to changing conditions.
- Fail mode is open.
- Water hammer can damage bellows.
- Superheat can damage bellows if it exceeds trap temperature
- Cooling leg required in some applications.
Features of Hoffman Specialty Thermostatic Traps:
- Brass bodies provide resistance to moderate water hammer and
- Stainless steel Dura-Statâ modules are easily replaced
without disturbing piping connections.
- Compact size reduces installation space requirements.
- Inexpensive purchase price.
- Range of seat pressures available - up to 125 psig.
Primary Applications of Thermostatic Traps:
- Radiators, convectors, unit heaters.
- Cooking kettles.
- Heating coils.
- Tracer lines.