Specialist compressor manufacturer CompAir has added to its range of oil-free single screw compressors with the new energy efficient DH series in 15, 22 and 37 kW versions. The company’s oil-free products are designed for applications needing high quality ‘active’ air, ie air that comes into contact with the process it serves and must be absolutely free of pollutants. The new units are water injected models with the lowest specific energy rating in their class, deriving from a sophisticated speed regulator and the inherent efficiency of the compressor design. The photo shows the primary components of the single stage, single screw unit which works on the same principle as the refrigeration screw compressor.