Abstract: A refrigerant charging cylinder for vapor refrigeration systems has a valve mounted on a refrigerant tank in which a refrigerant is partially liquid and partially gaseous, with the tank being arranged during use thereof with the gas between the liquid and the valve. Included in the valve is a saturated vapor pipe which extends into and terminates above a maximum level of liquid refrigerant in the tank, while a liquid refrigerant pipe mounted within the saturated vapor tube extends into the liquid refrigerant. By this arrangement, a flow of gaseous refrigerant through the saturated vapor tube will draw liquid refrigerant through the liquid refrigerant pipe, mix the liquid refrigerant with the gaseous refrigerant, and form a vapor that can be fed to the suction side of the compressor of a vapor-compression refrigeration system while the compressor is operating.