In compressed air system, one of the most misleading connotation is “Oil Free Screw Compressor is oil Free”.
The name Oil Free Screw Compressor refer to Rotary Screw Compressor which can meet the ISO 8573-1 class 1 or class zero standard. It means the produced compressed air from the compressor will have less than 0.01mg/m3 of oil vapor or aerosol.
However, a lot of users have the wrong understanding that the Oil Free Screw Compressor do not uses lubricating oil in the system ! This is a wrong perception. In Oil Free Screw Compressor, the rotating gears and bearing are still lubricated by oil. This lubricating oil will have to be changed every 4000 running hours, in some cases 8000 running oil (for those who uses synthetic oil). Waste oil will be generated during the service intervention.
As today industrial technology, to achieve real “Oil Free”, meaning the entire compressor do not uses any lubricating oil, not gear oil, not compressor oil, or greases; the only solution will be compressor that uses Magnetic motor and magnetic bearing.
So, the next time when someone recommend you with Oil Free Compressor (regardless whether it is rotary screw, centrifugal, or other technology), do ask whether compressor itself still uses any lubricating oil.