System for monitoring sterilant vapor concentration

• US 4,843,867 A
• Filed: 12/30/1987
• Issued: 07/04/1989
• Est. Priority Date: 12/30/1987
• Status: Expired due to Term

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: American Sterilizer Company (Steris Corporation)
• Inventors: Cummings, Arthur L.
• Primary Examiner(s): Lacey, David L.
• Assistant Examiner(s): Hanoharan, V.
• Application Number:
  US07/139,991
• Time in Patent Office: 552 Days
• Field of Search: 203/1, 203/91, 203/2, 203/3, 203/12, 203/DIG. 18, 422/27, 422/28, 422/111, 422/112, 422/83, 422/98, 364/413, 364/497, 364/499, 364/500, 364/501, 374/28, 73/336.5, 73/23
• US Class Current: 73/29.03
• CPC Class Codes: A61L 2/20 Gaseous substances, e.g. vapours
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation
• CPC Class Codes: G01N 25/66 by investigating dew-point
• CPC Class Codes: Y10S 203/19 Sidestream

Abstract

A system is provided for determining the concentration of a condensable vapor in the presence of at least one other condensable vapor, such as hydrogen peroxide and water vapors. The system includes generally a dew point sensor, a device for measuring at least one additional property of at least the other vapor such as relative humidity, and a microprocessor for fitting the dew point and additional property measurements into a modeled construct representative of the relationship between the vapors at a plurality of concentrations for each such vapor and at a plurality of corresponding dew point measurements. When used to determine the concentration of sterilant vapor in a sterilization system, the system also includes a sterilization chamber and an injector for injecting a measured quantity of the multicomponent condensable vapor into the chamber.

Claims

1. A system for monitoring the concentration of a first vapor in the presence of at least one other vapor comprising:

a chamber;

means for injecting a predetermined quantity of a multicomponent vapor into said chamber, wherein said multicomponent vapor is formed from component vapors comprising a condensable first vapor and at least one other condensable vapor;

means for measuring a primary property of said multicomponent vapor;

means for measuring a secondary property of at least one component of said multicomponent vapor; and

means for fitting said primary and secondary property measurements into a modeled construct representative of the relationship between said first vapor and said at least one other vapor at a plurality of concentrations of each said component vapor and at a plurality of said primary property measurements correlating to each said component vapor concentration.

2. The system of claim 1 wherein said first vapor is hydrogen peroxide vapor, said other vapor is water vapor, said means for measuring a primary property is a dew point sensor and said means for measuring a secondary property is a relative humidity sensor.

3. The system of claim 1 wherein said means for measuring said secondary property is a thermal conductivity sensor.

4. The system of claim 1 wherein said means for fitting measurements is a microprocessor having means for storing said modeled construct and means for communicating data from said primary property measuring means and said secondary property measuring means to said microprocessor.