GB871503A - Method of and apparatus for cold sterilisation by means of bactericidal gases - Google Patents

Abstract

871,503. Sterilizing foodstuffs; sterilization. GEWALT, R., and STEIN, E. July 3, 1957 [July 3, 1956; Jan. 26, 1957], No. 21094/57. Classes 49 and 81(1). Foodstuffs, medical appliances, medicines, sera, &c., are cold sterilized, i.e. sterilized at temperatures where heat alone is not effective, by treatment with bactericidal gases, e.g. alkylene oxides or alkylene imines, in a pressure chamber, the sterilization being effected at a pressure between 3 and 6 atmospheres (gauge) with a mixture of bactericidal gas and a gas having no bactericidal or sterilizing effect at atmospheric pressure, e.g. carbon dioxide. Mixtures of ethylene oxide and carbon dioxide in a weight ratio of from 1: 9 to 1: 25 are specified, sterilization being effected preferably between 20‹ C. and 60‹ C. The materials to be sterilized may be unwrapped or wrapped in plastic foil; the sterilization at superatmospheric pressures of loam wrapped in a polyethylene foil of thickness about 50Á is described as illustrating the sterilizing effects of a mixture of ethylene oxide and carbon dioxide by diffusion through the foil. In Fig. 2 the bactericidal mixture is held under pressure in a cylinder 1 from which it is passed through a pressure-reducing valve 5 to a preheater 6. The gas is led through a check valve 8 to a pressure chamber 10 containing the materials to be sterilized. The chamber 10 has electrical heating means 13, a discharge conduit 14 and a low-pressure manometer 15 connected thereto. Discharged gas is passed to an absorption chamber 17 having in its lower part 19 an absorptive solution for ethylene oxide, e.g. calcium chloride solution. A safety valve 24 is inserted in a conduit 23 leading from the chamber 10 to the absorption chamber 17. During operation thermostats (not shown) regulate the supply of electrical current to heaters 6 and 13, thereby maintaining a gas temperature of between 20‹ C. and 60‹ C. Gas pressure is regulated by valve 5.