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Steam Traps and steam equipment » Thermostatic steam trap BP22

Like all thermostatic steam traps, the Balanced pressure trap contains a temperature sensitive element, which automatically adjusts itself to varying steam pressures.

The housing contains a metal bellows assembly, with a fixed end, and a free moving end, the latter operating needle valve. The bellows contain a liquid with a boiling temperature below that of water. If alcohol is used, this temperature difference is approx, 12°C, which is valid for a pressure range of approx, 0-10 bar (beyond this pressure the difference increases, and at 20 bar it has become 28°C).

At relatively low temperatures the bellows are in the neutral position; in consequence valve a is open, and the trap discharges condensate and air.

When the condensate temperature rises to a level of 12°C below that of saturated steam, the alcohol boils, creating an internal pressure, sufficient to expand the bellows and to close valve a against the inlet pressure. Undercooling below this critical level will cause the valve to open once more.

The operating principle of this trap (which has been on the market for many years), is extremely simple and efficient. Obviously, there are also inherent disadvantages, the main one being that the bellows are apt to rupture (fatigue or water hammer). However the use of this trap is fairly widespread for the lower pressure ranges up to say 10 bar. (The body is often made of brass or bronze, which makes it unsuitable for various types of "treated" condensate).

Thermostatic steam traps BP22
Other Thermostatic steam traps:


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LBK22 Thermostatic steam traps BP22
Limiting Conditions
RatingANSI 300
PMA50 bar
Max Differential Pressure (Barg)22
1/2" - 3/4" - 1"
ScrewedASME B1.20.1 (NPT) BS21 (BSP)
Socket weldASME B16.11
FlangedASME B16.5 - UNI - DIN

Main Features:

Excellent air venting

Can be installed in any position

Maximum thermal efficiency under varying conditions

Sub cooling 10°C

Simple and reliable construction

Ordering Information:

Inlet pressure

Back pressure

Operating temperature

Condensate load

End connections

Thermostatic steam traps BP22
1BodyASTM A105 
2CoverASTM A105 
3GasketSW 316/GraphiteX
4Valve AssemblySSX
5ScreenSS 316LX
7PlugASTM A1058X
Thermostatic steam traps BP22
Size (inches)H1H2SWRF (150#)RF (300#)RF (600#)

Dimensions: L, H1, H2, are in millimeters (mm)



Prior to installation, clean the lines by blowing through at full steam pressure to remove dirt.

For steam trapping applications the trap should be fitted below the equipment to be drained and as close to the drain point as possible.

Always open isolation valve slowly until normal operating conditions are achieved to avoid system shocks.


The trap can be maintained without disturbing the piping connections. Ensure that trap is isolated upstream and downstream before attempting to dismantle it. Allow the trap to cool before dismantling.

Item 3,7 (gasket), 4-5 (valve assembly), 6 (screen can be replaced bring the traps as new conditions).




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Address: L. Maggi, 19 - 26841 Casalpusterlengo (LO) Italy

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