Optimum hydrogen peroxide vapor sterilization system

• US 5,508,009 A
• Filed: 05/16/1995
• Issued: 04/16/1996
• Est. Priority Date: 03/13/1992
• Status: Expired due to Term

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: American Sterilizer Company (Steris Corporation)
• Inventors: Childers, Robert W., Upchurch, Donald C., Rickloff, James R.
• Primary Examiner(s): Warden, Robert J.
• Assistant Examiner(s): Thornton, Krisanne M.
• Application Number:
  US08/442,468
• Time in Patent Office: 336 Days
• Field of Search: 422/1, 422/28, 422/32, 422/33, 422/34, 422/292, 422/295, 422/297, 422/300, 422/306, 422/905, 422/105, 422/108, 422/110
• US Class Current: 422/292
• 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 sterilization method is provided which includes the steps of measuring the pressure within a sterilization chamber injecting a sterilant vapor into a flow of carrier gas, introducing the sterilant vapor and carrier gas into and through a sterilization chamber, and adjusting the rate of sterilant vapor injection to reach a pre-determined percentage of saturation limit for the sterilant vapor in the chamber, immediately following the introduction of sterilant vapor and carrier gas into the chamber, in response to the measured pressure. The predetermined saturation limit is selected to optimize the rate of sterilization, while avoiding substantial condensation of the sterilant.

Claims

1. A system for optimizing sterilization with a sterilant vapor, comprising:

a sterilization chamber comprising an inlet port and an outlet port, said chamber being fluidly connected to a vacuum means;

an injection assembly for injecting a sterilant vapor into a carrier gas;

means for flowing the sterilant vapor and carrier gas into the chamber through the inlet port, through the chamber, and out of the chamber through the outlet port;

a measuring unit for predetermining the relative humidity, pressure and temperature of the carrier gas;

a sensing unit for sensing a characteristic in the sterilization chamber during a sterilization cycle, said characteristic selected from the group consisting of pressure and temperature;

a first regulating unit for regulating the rate of injection of the sterilant vapor into the carrier gas to maintain a predetermined percentage of the instantaneous saturation limit for the sterilant vapor in the chamber, wherein the rate of sterilant vapor injection is responsive to the sensed characteristic in the chamber and the predetermined relative humidity, pressure and temperature of the carrier gas.

2. The system according to claim 1, further comprising:

means for predetermining a range of chamber pressures which correspond to a predetermined range of percentages of the saturation limit for the sterilant vapor in the chamber;

a second regulating unit for regulating the rate of sterilant vapor injection into the carrier gas to reach and maintain the predetermined range of percentages of the saturation limit for the sterilant vapor in the chamber immediately following introduction of the sterilant vapor and carrier gas into the chamber, wherein the rate of sterilant vapor injection is responsive to the corresponding, predetermined range of pressures which includes the sensed pressure in the chamber.

3. The system according to claim 1, wherein the sterilization chamber is a cassette.

4. The system according to claim 3, further comprising an item to be sterilized having at least two open ends and a fluid path there-between and a connector to couple said item at one end to the inlet port or outlet port of the sterilization chamber.