GB943150A - Method and apparatus for sterilising containers - Google Patents

Abstract

943,150. Sterilizing containers. METAL BOX CO. Ltd. April 19, 1962 [May 17, 1961], No. 18008/61. Heading A5G. A method of reducing the level of bacterial contamination of an open-mouthed container for food or liquids sensitive to bacterial contamination consists of sterilizing the container by igniting in the container an explosive mixture of gases, thereby to subject the interior surface of the container to rapidly generated heat and immediately thereafter inserting food or liquid into the container and effecting closing of the container. Also, an apparatus for carrying out the method comprises a conveyer arranged to move an open-mouthed container to a filling and closing machine and at a position immediately prior to that at which the container is moved into the machine, means to provide an explosive mixture of gases in the container, and means for effecting ignition of the explosive mixture in the container. The method of the invention is particularly suitable for sterilizing plastic coated or waxed paper containers, which cannot be heated directly. In an embodiment, the explosive mixture of gases is created in the container by introducing an inflammable gas into air contained in the container. Ignition means may be present so that ignition is effected when the gas/air mixture reaches flash point. In another embodiment, a predetermined volume of an explosive mixture of gases is introduced into the container. The means for effecting ignition may comprise a radiant heat appliance supported for movement into and out of the container. Alternatively, the ignition means may comprise a device, of known form, for producing a spark capable of igniting the explosive mixture. In the Figure, an openmouthed waxed paper carton 1 is placed on a support or conveyer 2 so that an igniting device can then be moved, preferably automatically, into the carton through the mouth thereof. The igniting device is a radiant heat appliance having an electrically heated platinum spiral 3. Town gas is slowly admitted through a pipe 11 into the carton and mixes with the air present. The latter is augmented by compressed air delivered through a pipe 12 via a cotton wool filter 14. The admitted gas and air may be diverted by means of a baffle 13. After ignition at the flash point, the carton is filled with food or liquid and then closed.