... -cool oilless series The piston machine is divided into: air-cooled, water-cooled series of micro oil micro oil series, air-cool oilless ... used copper wire, life of up to eight years. Air cooled oil series:1, large air volume, low noise;2, with ... , smooth operation, the longest service life. Water cooled oil series:1, stable operation, low noise;2, water cooling, low temperature rise;3, longer ...