Compressors rolling piston

Figure 4.14 Rolling piston compressor (Courtesy of Rotorx Company)...

Suction traps are now widely used, particularly on rolling piston and scroll compressors, to prevent liquid passing into the compressor. 

Most screw compressors are of the oil-lubricated type. There are two types—the semihermetic and the open-drive type. In the former, the motor is located in the same housing as the compressor, while in the latter the motor is located outside of the compressor housing and thus requires a shaft seal. The only moving parts in screw compressors are two intermeshing helical rotors. The rotors consist of one male lobe, which functions as a rolling piston, and a female flute, which acts as a cylinder. Since rotary screw compression is a continuous positive-displacement process, no surges are created in the system. 

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