Oil-Free Two-Stage Variable Speed Centrifugal Compressors. CompAir's oil-free two-stage variable speed centrifugal compressors are the best compressed air insurance you can get. Air purity is critical for many applications where even the smallest drop of oil can cause product spoilage, or damage the production equipment. - Superb efficiency due to no gearbox and no contact parts - Variable speed technology minimising off-load running - Outstanding energy savings of up to 25% are easily achievable - No performance degradation - Lowest off-load power consumption of just 2.5% of full load power, equal to 7 kW for a 300 kW compressor - Smallest physical footprint - Lowest noise levels of just 69 dB(A)