Chemical sterilizer system

• US 5,122,344 A
• Filed: 01/31/1990
• Issued: 06/16/1992
• Est. Priority Date: 01/31/1990
• Status: Expired due to Term

• Current Assignee: Barnstead Thermolyne Corporation (Perspecta, Inc.)
• Original Assignee: MDT Incorporated
• Inventors: Schmoegner, John C.
• Primary Examiner(s): McMahon, Timothy M.
• Application Number:
  US07/472,817
• Time in Patent Office: 867 Days
• Field of Search: 422/28, 422/32, 422/33-37, 422/292, 422/298, 422/299, 422/305, 422/307, 422/111
• US Class Current: 422/111
• CPC Class Codes: A61L 2/06 Hot gas
• CPC Class Codes: A61L 2/18 Liquid substances or solutions comprising solids or dissolved gases
• CPC Class Codes: A61L 2/20 Gaseous substances, e.g. vapours
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation

Abstract

A chemical sterilizer system for sterilizing items by vaporizing a liquid chemical sterilant in a sterilizing chamber. Pre-evacuation of the sterilizer chamber enhances the sterilizing activity. Sterilant is injected into the sterilizer chamber from a prefilled shot chamber. Subsequent to the exposure period, spent sterilant is condensed and fresh air is pumped into the sterilizer chamber from a vacuum pump. An automated valving system uses a minimal number of three-way valves and one or more two-way valves to control the fluid flow functions in the sterilization cycle.

Claims

1. A method of sterilizing materials with a liquid chemical sterilant vaporized in a sealable, heated sterilizer chamber, comprising:

placing materials to be sterilized in said sterilizer chamber and sealing said sterilizer chamber;

heating said sterilizer chamber to a sterilant evaporation temperature;

pre-evacuating a portion of the atmosphere from said sterilizer chamber with a vacuum pump and producing a reduced pressure in said sterilizer chamber;

disengaging said vacuum pump from said sterilizer chamber at a predetermined reduced pressure therein;

introducing a predetermined quantity of said liquid chemical sterilant by gravity from a pre-filled shot chamber into said sterilizer chamber for vaporization therein and for mixture with residual atmosphere therein;

heating said sterilizer chamber and contents to a controlled sterilization temperature for vaporizing said introduced chemical sterilant;

maintaining said sterilization temperature for a timed period;

discharging spent vaporized sterilant and air from said sterilizer chamber through cooling means to condense and cool said vaporized sterilant;

engaging said vacuum pump to pump atmospheric air into said sterilizer chamber to rapidly cool said chamber and dilute said vaporized sterilant; and

passing said discharged, cooled and condensed spent sterilant to a condensate reservoir for separating said condensed sterilant from gases and vapors.

2. The method of claim 1, further comprising:

the step following the introduction of said sterilant into said sterilizer chamber of disengaging said shot chamber from said sterilizer chamber and prefilling said shot chamber for a subsequent sterilization cycle.

3. The method of claim 1 wherein said gases and vapors are withdrawn from said condensate reservoir and are passed through a filter.

4. The method of claim 1 wherein said sterilizer chamber is provided with a solenoid valve control system, sterilant inlet conduit means, exhaust conduit means, a liquid sterilant reservoir means with a vapor space, sterilant injection means including said shot chamber for supplying sterilant to said sterilizer chamber means, evacuation means with a suction port and a discharge port, spent sterilant condensing means, waste reservoir means with a vapor space and a drain, and electronic control means, said solenoid valve control system comprising:

first three-way valve means with a first port connected by a first conduit to said sterilizer chamber, a second port connected by a second conduit to the bottom of said shot chamber, and a third port connected by a third conduit to said sterilant reservoir means;

second three-way solenoid valve means with a first port connected by a first conduit to said sterilizer chamber, a second port connected by a second conduit to the top of said shot chamber, and a third port connected by a third conduit to said vapor space of said sterilant means;

third three-way solenoid valve means with a first port connected by a first conduit to said sterilizer chamber means, a second port connected by a second conduit to said suction port of said evacuation means, and a third port connected by a third conduit to the atmosphere;

fourth three-way solenoid valve means with a first port connected by a first conduit to said vapor space of said waste reservoir means, a second port connected by a second conduit to said discharge port of said evacuation means, and a third port connected by a third conduit to said sterilant chamber;

first two-way solenoid valve means with a first port connected by a first conduit to said sterilizer chamber means and a second port connected by a second conduit to said spent sterilant condensing means; and

condensate conduit means connecting said condensing means to said waste reservoir means;

wherein said first and second three-way valves are operable between a first position for filling said shot chamber with said liquid sterilant and a second position for injecting said liquid sterilant into said sterilizer chamber; and

wherein said third and fourth three-way valves are operable between a first position for evacuating said sterilizer chamber, a second position for blocking flow to or from said sterilizer chamber, and a third position for purging said sterilizer chamber with air pumped by said evacuation means;

said solenoid valve control system being operated to effect said method.