GB1122932A - Improvements in steam autoclaves - Google Patents

Abstract

1,122,932. Steam autoclave. F. UNDER. 13 Dec., 1966 [4 March, 1966], No. 55673/66. Heading A5G. A steam autoclave, wherein the pressure is automatically caused to fluctuate rapidly until all the air is expelled, comprises a chamber I connected to a thermostatically controlled steam generator 3 by conduit 2, a closing tank 5 connected to the steam generator via conduit 7 and solenoid-operated valve 6 and to the water storage tank 12 via one branch of a solenoid-operated 3-way valve 10 (the other two branches of which connect the chamber 1 and the dosing tank 5). The chamber 1 is also connected to the tank 12 via a conduit 15 and a selector valve 19 (which passes air and water 'but not steam). This conduit also contains a thermometer 16, a thermostat 17 and pressure switch 18, which are used to control the process. In operation, valve 6 opens and valve 10 connects chamber 1 and tank 5, the path between tanks 5 and 12 via conduit 13, 14 being closed. Steam passes from the generator to the autoclave chamber and any condensed steam flows back to tank 5 via conduit 9 &c., whilst air is expelled via conduit 15. When most of the air has been expelled, the selector valve 19 closes automatically and pressure rises rapidly in the chamber 1, due to consequent increase in pressure in tank 5 and faster supply of water to the steam generator. When the pressure reaches a predetermined value, pressure switch 18 operates to close valve 6 and to cause valve 10 to connect tanks 12 and 5 and disconnect chamber 1 and tank 5. Air residues oresent in chamber 1 then pass to valve 19 and cause it to open whereupon pressure drops, the pressure switch operates to reverse valves 6 and 10 and the cycle is repeated until no air is present. The system then remains sealed until the operating temperature is sensed by the thermostat 17, Which then operates to close valve 6 and reverse the position of valve 10 so that connection between chamber 1 and conduit 13 is interrupted. If the temperature drops, the thermostat operates to cause more water to enter the generator and thus to raise the temperature and this process is continued until a timer indicates that sterilization time has been achieved. The current to thermostat 17 and pressure switch 18 is then interrupted so that valve 10 moves to the position in which connection exists between conduits 11 and 13, but not between conduits 9 and 11. Pressure then drops in chamber 1 until equilibrium pressure is reached, when the one-way valve 24 allows water to pass from tank 12 to tank 5 and the apparatus is ready for further use.