The oil-free screw compressor element
No oil means that there is absolutely no oil for sealing the rotors and for cooling the compressed air flow, components and rotors. … The element can be cooled by cooling water that flows through Oil-free Screw Air Compressor china special pockets in the element casing.
In a lubricated screw compressor, the lubricant comes in direct in touch with the compressor inlet air and compressed air. … The oil contains anti-oxidants to attempt 
to reduce the breakdown of the lubrication properties because of internal conditions.