AN ELECTRICAL DEVICE FOR AUTOMATIC PROGRAMMING OF THE CON TROLS OF A PRESSURE STEAM STERILIZER/AUTOCLAVE AND LIKE P RESSURIZED STEAM VESSELS USING SOLENOID VALVE SYSTEM

摘要

An electrical device for automatic programming of the controls of a pressure steam sterilizer/autoclave and like pressurized steam vessels for sterilizing bottled load and having a sterilizer chamber, a steam jacket and a normally closed first solenoid valve for admitting steam into the chamber, a normally open second solenoid valve for slow exhaust of the sterilizer chamber, said electrical device comprising: a dial thermometer for indicating the temperature of the sterilizer chamber and having an electrical contact which closes when the temperature rises to the sterilizing temperature; a pressure gauge for indicating the jacket pressure and having an electrical contact which closes when the pressure rises to the working pressure of the sterilizer; a compound gauge for indicating the degree of pressure or vacuum existing in the sterilizer chamber and having an electrical contact which closes when the pressure in said chamber falls to atmospheric pressure; an automatic reset timer for determining the sterilizing period and having a timer motor and normally closed change-over contacts; a selector switch for programme selection; a first contactor for energizing said 1st & 2nd solenoid valves and having a coil and a plurality of NO-contacts and NC-contacts; a second contactor having a coil and a NO-contact and a pair of NC-contacts; a third contactor having a coil and a plurality of NO-contacts and a plurality of NC-contacts; an electrical circuit having input terminals connectable to an external power source through a main switch and comprising; a first circuit wherein said electrical contact of the dial thermometer is connected in series with said timer motor of timer and has a first NC-contact of said second contactor provided across said electrical contact of said dial thermometer, said first circuit being connected across said input terminals through the contacts of the first pole of said selector switch and a normally closed reset push button: a second circuit wherein the normally closed contact of said timer is connected in series with the coil of said second contactor, said second circuit being connected across said input terminals through said normally closed reset push button and the contacts of the first pole of said selector switch; a third circuit connected in parallel to the coil of said second contactor and having a NO-contact at the second contactor and a first NC-contact of the fourth contactor connected in series with the electrical contact in the pressure gauge, a start push button and the coil of said first contactor, a hold-on contact comprising a fourth NO-contact being provided across said electrical contact and said start push button; a fourth circuit having said electrical contact of the compound gauge in series with the coil of the third contactor with a first NO-contact of the third contactor connected across said electrical contact of the compound gauge said fourth circuit being connected to the change-over contact of said automatic timer; a fifth circuit connected across said coil of the third contactor and comprising a second NO-contact of said third contactor connected to an alarm device through the contacts of a third pole of said rotary switch; a sixth circuit connected in parallel to said first circuit and comprising said normally open second solenoid valve connected in series with a first NO-contact of the first contactor with said normally closed first solenoid valve connected in parallel to said second solenoid valve.