System and method for exhausting vapor from a heated pressure chamber

Abstract

A system and method of exhausting vapor, such as steam, from a pressure chamber following the sterilization phase of a sterilization cycle under superatmospheric pressure conditions are provided. The system and method preferably employ a microprocessor and an appropriate pressure transducer to measure the chamber pressure at the conclusion of the vapor exposure period to determine an initial chamber pressure. The method includes the further steps of exhausting vapor from the chamber for a period of time, preferably up to about one minute, to lower the chamber pressure, measuring the chamber pressure at the conclusion of such first period of time to determine a second chamber pressure and calculating the difference between the initial chamber pressure and the second chamber pressure to determine an exhaust rate. The exhaust rate is used to predetermine successively lower next target chamber pressures to be reached at the conclusion of successive intervals of a predetermined second period of time, such as three seconds, until a predetermined final chamber pressure is reached. Vapor is exhausted from the chamber during each successive interval of the second period of time until the target chamber pressure for that particular second period of time is reached. After each such interval of time, the chamber pressure is measured to determine whether the calculated next target chamber pressure has been reached.