Oil Sealed Rotary Vane Pumps operate according to the rotary vane principle.

The rotor is eccentrically positioned in the cylinder and has the slots for vane sliding. The centrifugal forces when rotates push the vanes towards wall of the cylinder through the slots of the rotor. The gas will be sucked in through a built-in anti suck back valve that prevents the pump from rotating backward at standstill, and goes into the cylinder. The gas will be compressed and pushed out through the exhaust opening located between the pumps housing and oil sump. The oil will be fed into the pump module from the oil sump for sealing and lubrication by differential pressure between pump module and oil sump. The discharged oil as a mist with gas will be collected through the oil separator(s) in the upper part of oil sump. The collected oil will be drawn into the pump inlet side for re-circulation by the pressure difference between suction and pressure side through a float valve (F version) or through the return line (L version).. Gas Ballast (in case equipped) will be working by sucking ambient air into the cylinder for prevention of accumulation of condensates(water) from process gas.