Compressors closed-suction unloaders

Constant-speed control should be used when gas demand is fairly constant. With this type of control, the compressor runs continuously but compresses only when gas is needed. Tiiree methods of unloading the compressor with this type of control are in common use (1) closed suction unloaders, (2) open inlet-valve unloaders, and (3) clearance unloaders. The closed suc tion unloader consists of a pressure-actuated valve which shuts off the compressor intake. Open inlet-valve unloaders (see Fig. 10-89) operate to nold the compressor inlet valves open and thereby prevent compression. Clearance unloaders (see Fig. 10-90) consist of pockets or small reservoirs which are opened when unloading is desired. The gas is compressed into... 

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