The liquid ring pump compresses gas by rotating a vane impeller within andeccentric to a cylindrical casing. Liquid (usually water) is fed into the pump and,by centrifugal acceleration, forms a moving cylindrical ring against the inside ofthe casing. This liquid ring creates a series of seals in the space between theimpeller vanes, which form compression chambers. The eccentricity between theimpeller's axis of rotation and the casing geometric axis results in a cyclicvariation of the volume enclosed by the vanes and the ring.Gas, often air, is drawn into the pump via an inlet port in the end of the casing.The gas is trapped in the compression chambers formed by the impeller vanesand the liquid ring. The reduction in volume caused by the impeller rotationcompresses the gas, which reports to the discharge port in the end of the casing.