... 2)two types:Totally-hermetic, semi-hermetic compressor for cold room 1compressor for cold room include total-hermetic piston compressor and Semi ... -type piston compressor 2. compressor for cold room is mainly composed of a machine body, crankshaft, connecting rod, piston, valve, seal, pump, ... the gas of the cold storage , provides the power for the cold storage cycle 4.the character of semi-hermetic ...