Patent GB-964082-A (GB)
Title: Improvements in or relating to sterilizing apparatus
Inventor: URRY JOHN THOMAS
IPC: A61L2/00
Filed: 1960-01-18
Abstract: 964,082. Methods and apparatus for sterilizing articles. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Nov. 3, 1960 [Jan. 18, 1960], No. 1767/60. Heading A5G. A method of sterilizing an article consists in passing the article on a common conveyer successively through adjacent heating and cooling chambers thermally insulated from each other during the heating and cooling stages wherein at each stage the heat exchange is effected by forced convection and recirculation of a stream of air or gas which is subdivided into at least two streams which pass round the article and are then recombined into a return stream for recirculation. A sterilizing apparatus for carrying out the method comprises heating and cooling chambers 2, 3 respectively, a conveyer 6 for conveying the body through the chambers in succession, thermally insulated doors 12 for closing and opening the chambers, and means for co-ordinating the motion of the conveyer with the opening and closing of the thermally insulated doors so that the heating and cooling chambers are respectively thermally insulated when the body is undergoing the heating and cooling steps. As shown, the sterilizer consists of an inlet chamber 1, a heating chamber 2, a cooling chamber 3, and an outlet chamber 4, all enclosed within a panelled framework 5 and an endless conveyer 6 arranged to pass through the chambers on guide rails 7 and round sprocket wheels 8. The heating and cooling chambers are located in thermally insulated compartments 9, 10 respectively, with interconnecting openings 11 over which slide thermally insulated doors 12 which are operated by chains 13 through a lever 14 and a cam 15 synchronized with the movement of the conveyer 6. By this means an open wire tray of surgical instruments 16 which is placed on the conveyer 6 in the inlet chamber is carried through the heating chamber 2, cooling chamber 3 and delivered into the " out " chamber 4 where it may be removed via a door at the side of the sterilizer and during its passage from the inlet chamber to the outlet chamber, the conveyer is arranged to dwell for a controlled period of time in each chamber during which the heating and cooling processes take place, the doors 12 being synchronized to remain closed during the period that the conveyer is at rest. The conveyer is driven by a suitable indexing mechanism 17 controlled by an adjustable timing instrument which is mounted on a control panel (not shown). The heating of the instruments is by forced air convection recirculating within the compartment 9 obtained by means of a bank of heating elements 19 located in front of a circulating fan 20, the outlet of which connects with the bottom of a U-shaped plenum chamber 21, and which forces hot air through narrow slits 22 arranged at a short angle to impinge at high velocity on the upper and lower sides of instruments in the tray 16. Control instruments are provided to adjust the maximum air temperature to a level which will ensure rapid sterilization without overheating the smallest instruments in the tray. The use of forced air convection ensures that no instrument will reach a higher temperature than the maximum controlled temperature of the circulating air, irrespective of the time the tray is in the heating chamber. The cooling chamber is similar in construction and operation to the heating chamber, cooling tubes being provided in place of the heating elements in the heating chamber, and cooled by a suitable medium such as water or refrigerant. The " in " and " out " chamber doors (not shown) and the drive for the conveyer, are interlocked to prevent movement of the conveyer while the doors are open, and also prevent the doors being opened while the conveyer is in motion. Further interlocking prevents movement of the conveyer before a predetermined sterilizing temperature has been reached and also should the " out " chamber be occupied by a loaded tray.