By using high-speed direct-drive motors, Atlas Copco says it has developed the most efficient oil-free compressor that it has ever produced. It claims that the three-stage centrifugal compressor is up to 4% more efficient than it previous best-performing oil-free compressors.

It adds that the ZH 350+ (above) is the first commercial three-stage centrifugal compressor to use high-speed motors without a gearbox. The absence of a conventional gearbox, allows the 350kW compressor to eliminate transmission losses that can reduce energy efficiencies by up to 9% in compressors of this size.

Further savings arise from the three-stage turbo design which is said to result in lifecycle costs that are 3% lower than oil-free screw designs and 18% lower than two-stage turbo systems. The system delivers up to 9% more air per unit of power, and 46% more power per square metre of floorspace.

Atlas Copco estimates that the compressor, which delivers compressed air at 7–8 bar, could save around €24,000 in annual running costs compared to a conventional design.