A diaphragm compressor is a specialized piece of equipment used to compress gases when little or no leakage is tolerable. The difference between an ordinary piston compressor and a diaphragm compressor is in the method of compression and the accompanying seals. A diaphragm compressor has a piston with piston rings, but the piston moves a volume of hydraulic oil. The oil bends a set of diaphragms up and down, and the diaphragms compress the gas. It usually has an electric motor as the prime mover, with flexible belts for power transmission.