GB698972A - Improvements in and relating to sterilising apparatus - Google Patents

Abstract

698,972. Controllers ; interrupters. SCHAERER AKT.-GES, A. May 22, 1951 [June 24, 1950], No. 11953/51. Class 38 (iii) and 38 (v) [Also in Group VI] In a sterilizing apparatus of the kind wherein the operation of the valves controlling the various phases is effected in correct sequence automatically, the valves are mechanically operated by means of a motor 16 driving a threaded shaft 14 along which moves a tapped block 15 which contacts the valve stems, control means being provided for controlling the motor so that the valves are opened and closed for the requisite times in the requisite sequence, the motor being stationary during periods when the valves are not in the course of being opened and closed. At the beginning of a cycle, a control disc 22 is turned manually to the position shown in Fig. 2, when switch 24 provided with a follower 24a closes, thereby exciting contactor 3 and energising heaters 2. The maximum steam pressure generated is controlled by a pressure-operated switch 5, which, when a predetermined pressure is reached, opens the energizing circuit of contactor 3. When the operating pressure is reached, spring tube 6 closes switch 7 to start motor 23 rotating the control disc. After a short interval, follower 21a engages the first notch 22a on disc 22 thereby exciting the lower winding on contactor 20. This starts motor 16 in such a direction as to move block 15 downwards from air-admission valve 8, which thereupon closes, to open valves 9 and 10 which connect the sterilizing chamber 1 and steam jacket 1a respectively to a steam-jet vacuum ejector 13. Evacuation continues while the motor 16 is switched off for a time corresponding to a mid-level portion 29 on the disc. The motor is again started by the second notch 22a, and moves block 16 so as to close valves 9 and 10, and to open valve 11, admitting steam from the jacket 1a to the chamber. The motor is again switched off for a time corresponding to a mid-level portion 29a. At the third notch 22a, the block is moved downward again to open discharge valve 12 whilst keeping valve 11 open, the valves being suitably closely spaced. After a short period in which the chamber is swept by steam, follower 21a engages a projection 22b which tips switch 21 in the opposite direction, reversing the rotation of the motor and movement of block 15. Thereupon, the follower runs on the midlevel portion 29b. The alternate tipping of the switch is repeated several times, until notch 22c is reached. This is of sufficient length to close valve 11 and open 12. The steam pressure is released in a period corresponding to the mid-level portion 30, whereupon projection 22d causes the block to move upwardly to a position in which valves 9, 10 are opened. These remain open for a period corresponding to midlevel portion 29d during which the chamber is evacuated (drying phase). Then the last projection 22b switches the motor to open the valve 8 through which filtered air flows into the chamber. An abutment 22e then tips switch 24 to discontinue the heating and to open the supply to the motor 23. As the steam pressure drops, switches 5 and 7 open putting the whole apparatus out of action. A clockwork drive may replace motor 23.