Oil-Injected Screw Compressors

Compression is achieved by the intermeshing of two helical rotors with a minimum of play or clearance in a suitable casing.

On rotation, gas is drawn in to fill the space between adjacent lobes, the volume increasing from zero initially to a maximum (induction process).During this phase, the interlobal space is connected to the gas intake of the compressor.

On further rotation of the rotors, the gas is transported onwards and separated from the intake space by the rotor lobes. The gas volume trapped between the rotors, which are enclosed by the casing with very small clearances, is reduced progressively on the delivery side of the compressor until the interlobal space is exposed to the outlet port , through with the gas is discharged.

The location and size of the outlet port determines the compression ratio and the magnitude of the discharge pressure that can be achieved.The gas is subsequently completely discharged against the backpressure prevailing on the delivery side.

This process is repeated several times on each rotation of the male rotor, so that in contrast to compression, by piston compressors, virtually continous and pulse – free compression takes place without any dead spaces.