GB914139A - Improvements in or relating to gas sterilizers - Google Patents

Abstract

914,139. Sterilizing apparatus and methods. WILMOT CASTLE CO. Dec. 30, 1960, No. 44806/60. Class 81 (1). An apparatus for sterilizing comprises an enclosed chamber 12, means for evacuating the chamber, a water-vapour injecting arrangement, means for introducing a sterilizing gas, and means to control the operation so that pressure in the chamber is reduced to a predetermined level, the water-vapour injecting arrangement releases water vapour into the evacuating chamber to humidify the chamber atmosphere to a preselected level, the means for introducing sterilizing gas into the chamber become operative only after the chamber atmosphere has been maintained at the preselected humidity value for a predetermined time period and the evacuating means are re-operated after a predetermined time period has followed the introduction of the sterilizing gas. As shown, the apparatus which automatically performs a predetermined sterilizing cycle comprises an evacuable chamber 12 closable in a gas-tight chamber by a door 13 and capable of being maintained at a predetermined temperature, a vessel 31 for containing a predetermined amount of water, a normally closed valve 20 actuated by a vacuum switch for injecting water-vapour into the chamber, a source 45 of sterilizing gas, e.g. ethylene oxide mixed with a diluent gas such as carbon dioxide or halogenated hydrocarbon under pressure, connected via a second normally closed valve 51 to the chamber and a normally open valve 51 for admitting air which has passed through bacteria retentive filters 54 into the chamber, a sterilization cycle being controllable such that, if the door is shut the vessel contains the predetermined amount of water and the source of gas contains gas at a predetermined pressure, the cycle commences, the normally open valves close, air is evacuated from a chamber until a predetermined degree of vacuum has been obtained, the vacuum switch is actuated, a predetermined amount of water vapour is injected into the chamber and is maintained there for a predetermined period sufficient to allow the water-vapour to diffuse throughout the container and material therein, a second normally closed valve 51 opens, sterilizing gas flows into the chamber so that a predetermined supra-atmospheric pressure is attained, the gas is held in the chamber at this pressure and at predetermined temperature for predetermined period, the gas is then evacuated from the chamber until a predetermined degree of vacuum has been attained, the normally open valve opens and bacteria-free air is admitted to the chamber until substantially atmospheric pressure is attained in the chamber.