The liquid ring vacuum pump has only one moving part -- a balanced rotor that runs without any metal-to-metal rubbing contact. Such simplicity is possible because all functions of mechanical pistons or vanes are actually performed by a rotating band of water which serves as a liquid compressant. While power to keep it rotating is transmitted by the rotor, this cylindrical ring of water tends to center itself in the cylindrical body of the compressor. In the circular love design shown here, rotor axis is offset from body axis. As the schematic diagram shows, water almost fills then partly empties each rotor chamber during a single revolution. That sets up the piston action. The air inlet on the vacuum side and the air discharge to atmosphere are separated by means of ported openings, either in a stationary inner cone as shown or in the headplate at the side of the rotor.