GB958582A - Improvements in the means for operating the control valves of autoclaves - Google Patents

Abstract

958,582. Valves. TEMPTRIP Ltd., and W. HURSTHOUSE. Nov. 23, 1961 [Aug. 23, 1960; April 14, 1961; June 15, 1961], Nos. 29046/60, 13425/61 and 21581/61. Heading F2V. [Also in Division G3] In an autoclave, fluid regulating valves for each stage of a sterilizing process are diaphragm operated valves, which are opened by pressure supplied to the diaphragm chambers by pilot valves 3, these pilot valves being opened by cams 2 on a shaft 1 which makes one revolution for a complete process, the cam-shaft being driven by a main high speed motor 13 the spindle of which can be driven through a free-wheel clutch 16 by a slow speed motor 15, the high speed motor being started and out cut by switches operated by tappets on a disc mounted on the cam-shaft or on a shaft driven therefrom, to speed up the drive between the operative positions of the cams. The diaphragm valves (not shown) are connected through pipes 5 by the pilot valves selectively to pressure or release connections 4, 6 respectively. Camshaft 1 is constantly driven at a slow rate, e.g. one revolution in thirty minutes, by motor 15. The high speed motor 13 is coupled to the camshaft through a reduction gear 14 and a second freewheel clutch 12 to rotate it e.g. at a rate of one revolution in two and a half minutes. The timing individually of the cams is arranged through a disc 18 on a shaft 18a rotatable with the cam-shaft and carrying spaced abutments 17 which engage a start switch 19 controlling the motor 13. This motor continues to run until a following one of a corresponding number of spaced pins 20 on the disc engages and opens a cut-out switch 21 so that the cam-shaft is then driven at the slow speed until motor 13 is restarted by the next abutment 17. The pins 20 are adjustable angularly to alter the length of time each cam is operative. An additional set of cut-out switches 22, 23 may be similarly operated to control an alternative cycle selected by a selector switch. Shaft 18a drives a further cam-shaft 31 carrying cams 32 which operate banked switches 33, 34, one of which puts a vacuum operated switch into the circuit of the slow speed motor. As a result during a vacuum stage of the process, if the required vacuum has not been obtained when motor 13 is cut out then both motors will stand still until the vacuum switch starts the slow speed motor 15. Another one of the banked switches 33, 34 brings in a temperature control switch operating similarly to the vacuum switch during a steaming stage. Other of the banked switches control indicator lights indicating the stages being carried out. Any stage not provided automatically can be met by turning manually a handle attached to the shaft 18a. In addition to a normal steam supply controlled through one of the pilot valves 3, an additional steam supply at a higher temperature may be supplied by an additional diaphragm valve controlled by a pilot valve operated through a thermostat, whereby to bring the autoclave quickly up to a required temperature. Alternatively in such a stage the thermostat may start a motor of which a high speed spindle operates through a centrifugal member the pilot valve controlling the high temperature steam, whilst a slow speed spindle of this motor controls through a cam a regulating valve in the high temperature steam supply at intervals to avoid a too rapid increase in the temperature in the autoclave. The pilot valves may each comprise a valve ball 29, Fig. 5, carried by a pivoted arm 28 and operating between two seats 25, 26.