A single-stage compressor, operating at a discharge pressure of 9 bar, has a compression ratio of 1:9 (Ratio of Suction to Discharge of a Screw Airend) .In a two-stage compressor operating at the same discharge pressure, the compression ratio is divided between the two-stages of tandem airend and is about 1:3 in each stage. This makes the airend more reliable and efficient due to smaller loads on the bearings. The volumetric efficiency of two-stage is better than single-stage compression.
