Valves in Compressor:-
o Ring Valves:-
· Simple Ring Valve:- Plate rings guided in the valve guard limited adaptation.
· Damped Ring valve:- use gas damping by entrapped gases
· Contoured Valve ring:- contoured ring valves with chamfered valve seat
o Ported plate valve:-
· Simple plate valve
· Double damped plate valve:- Damper plate with springs placed between valve plate and valve guard
o Channel Valve:- use straight sealing elements with u cross section. Each channel is loaded with springs.
o Feather Valve:- Leaf type sealing element. It is also the spring, must have a multiple guard and seat.
o Poppet valve :- Mushroom type sealing element.
o Double deck valve :- Two valve separated by a spacer and held together by a sleeve, used if valve area achieved is insufficient and added clearance can be tolerated.
o Concentric valves :- The suction and discharge valves are arranged concentrically either with one body, or as two individual valves.
o Reed valve :- Primarily for small refrigeration and air compressors. Single seat plate valve with reeds positioned on both sides of the seat plate. Reeds are thin strips. It is held on one end and covers a port in the other end.
When reciprocating compressor valves fail they can no longer provide effective sealing. The leak introduces the same gas back into the compression process where it is heated again. The re-compression results in a temperature near the valve.
Opening & Closing of Valves:-
Suction valve open when cylinder pressure is lower than the pressure of the gas in the suction line.
Discharge valve opens when cylinder pressure is higher than the pressure of the gas in the discharge line.
When the pressure across the valve are equal, the valve seats or closes and prevents back flow.