Multi-Pressure Capability for Screw Compressors

By 16 May 2018

It is sometimes convenient to supply a compressor with different pressure capabilities to meet the varying demands of the plant hire industry. It is clearly not possible in an installation with a fixed prime mover to supply a range of pressure capabilities while delivering the same output. However it is possible in a limited way to exchange delivery volume and pressure. This can be achieved by what amounts to a shortening of the L/D ratio of the screw elements. A portion of the inlet length of the screws can be by-passed through one of a series of passages in the compressor casing, which vent some of the inlet air according to the desired pressure setting. The operating condition is set initially (which can be key locked to avoid improper use). Thus, in one particular compressor it is possible to have the following variations: