Cooling of a jacketed autoclave or steam sterilizer is carried out by allowing a film of water to flow down the inner wall of the sterilizers jacket space. Condensate from the jacket space is drawn into the water ring pump provided for vacuum in the autoclave jacket. The condensate is conducted to the water side of the pump while the normal suction line is connected at the pump to the gas zone. Thus, the water ring pump draws condensate from the lowest point of the jacket to the water side, and gas from the jacket space to the normal suction inlet. During the process of sterilizer cooling, a stream of water and air from the water ring pump is conducted to the upper part of the jacket space of the steam sterilizer and is allowed to flow as a film down the inner wall of the jacket space. Evaporation takes place with cooling of the jacket inner wall. This evaporation is enhanced by the lowering of pressure in the jacket due to the action of the water ring pump. Thus, the autoclave is cooled by a film of water flowing across the jacket inner wall while evaporating.
