The difference between oil-lubricating compressor and oil-free compressor usually refers to the amount of oil contained in the discharged gas. The amount of oil contained in the discharged gas of oil-lubricating compressor is larger, and oil-free compressor is only 0.01ppm. There is also a kind of compressor named full oil-free compressor which don’t need lubricating oil and adopts self-lubricating material to lubricate. There is no any oil in the discharged gas and named with full oil-free compressor.