In a liquid ring pump, an impeller with at least 12 or more fixed blades is mounted eccentrically in a drum shaped casing between 2 end plates. As the impeller rotates the sealing liquid moves out by centrifugal force to the wall of the casing forming the liquid ring. The process gas is drawn into the pump by the expanding pockets trapped between the liquid ring and the impeller hub. The air is then discharged slightly above atmospheric pressure after being compressed as the pockets between the liquid ring and the impeller hub decrease.
As a vacuum pump the liquid ring can generate pressures down to 28.9"HgV and as a low pressure compressor with an atmospheric inlet will produce up to 30 psig at the discharge. Liquid ring compressors are also available as double acting machines and can produce pressures over 200psig at the discharge with an atmospheric inlet.