Separating stage 2. Oil filter position 3. Outlet of the oil filter The pumped medium containing oil particles enters the oil mist separator. Due to gravity, the oil drops to the bottom of the oil separating chamber while the pumped medium continues towards the outlet. The oil is pumped into the oil filter through the suction of the compression process. Once filtered, it is sent back into the compression chamber again through an oil return line and an oil supply line which are connected to the oil inlets. 1. Oil inlet to the vacuum chamber