What is the difference between oil-free and oil-less air compressors?
The terms are frequently intermixed but both refer to the absence of oil in the compressor chamber. More specifically oil-less compressors are compressors that do not contain oil anywhere in the compressor pump or crankcase. Oil-free compressors do not have any oil in the compression cylinder but use lubricant in the crankcase. In reciprocating compressors the oil is usually separated from the compression chamber by rings and distance pieces. Oil-free rotary compressors and centrifugals have a separate lubrication system which uses seals and vents to keep the oil separate from the compressed air.