172-65530MAJ-04 (P46/65 Series + BD2) 6 Oct 2021
5
Operation
Principle of Air and Condensate Discharge
1. Start-up: Discharge of Initial Air and Cold Condensate
At start-up, the bimetal air vent ring is cold and has therefore contracted, causing
it to ride up to the narrower area under the disc, thus lifting the disc off the seat
and holding the valve open. This allows for the rapid discharge of initial air and
cold condensate.
2. Steam Enters, Valve Closes
As the bimetal air vent ring is heated by the entering steam, it expands and slips
back down, freeing the disc. The rapid flow of steam creates a low-pressure area
under the disc. The pressure chamber above the disc retains its higher initial
pressure. This difference in the pressures above and below the disc pushes the
disc down against the valve seat, giving the closed valve a tight seal.
3. Condensate Discharge
When condensate enters the trap, the temperature in the pressure chamber
drops due to radiant heat loss, causing the steam to condense and the pressure
to drop. The inlet pressure then pushes up the disc, opening the valve and
allowing condensate to discharge. The bimetal air vent ring remains in its
expanded, low position state. When steam again enters the trap, the valve
closes, as in step 2.
Cold
Condensate
Air
Pressure Chamber
Steam
Condensate
Disc
Air Vent Ring
