Abstract: A closed circuit refrigeration system of successive coalescent/depth filters provides the almost total removal of liquid refrigerants from a refrigeration gas stream. The liquid refrigerant so extracted is then be returned to the suction side through a metering device such as a capillary line to provide intermediate cooling of the oncoming discharge gas. The auto cascade system utilizes short path plate heat exchangers. The properties of coalescent/depth filters place a physical barrier between the differing temperature/pressure regimes on the discharge side of the system. The provision of a start valve in a line connecting the gas discharge path and the return path close to the cryo-coil enables the use of hermetic compressors and eliminates the requirement for supplementary pressure vessels within auto-cascade cryogenic refrigeration systems.