Apparatus for controlling temperature below 212 degrees fahrenheit in a sterilizer chamber

Apparatus for sterilizing media in a chamber from a predetermined sub-atmospheric pressure correlation point below 212.degree. F. comprising:

• a closed sterilizing chamber for containing said media during sterilization;
• vacuum system means connected to said chamber for evacuating air and vapor therefrom, said vacuum system being operable continuously;
• a source of steam operatively connected to said chamber for supplying steam thereto;
• a steam regulator valve having electrically operable means and connected between said chamber and said source of steam for selectively injecting steam into said chamber and for cutting off steam supplied to said chamber;
• a pressure sensor operatively disposed to sense a sub-atmospheric pressure in said chamber;
• a temperature sensor operatively disposed to sense temperature in said chamber;
• a first relay operable by said pressure sensor at a preset sub-atmospheric pressure and having normally open first switch contacts;
• a second relay operable by said temperature sensor at a preset temperature and having second normally closed switch contacts;
• and
• circuit means connecting said first and second switch contacts in series with said electrically operable means for activating said valve to pass steam into said chamber when the pressure in said chamber reaches said preset sub-atmospheric pressure, whereat said first switch contacts are closed, and wherein said valve is deactivated by opening said first switch contacts to cut off steam from said chamber when the pressure in said chamber, as sensed by said pressure sensor, rises above said preset sub-atmospheric pressure, and wherein the aforedescribed cycle is continued until the temperature in said chamber has reached said preset temperature whereupon said temperature sensor operates said second relay to open said second switch contacts to prevent any further activation of said valve by said pressure sensor.