DECONTAMINATION OF ISOLATION ENCLOSURES
A system and method for decontamination of isolation enclosures includes a recirculating isolator configured to allow injection of a sterilant gas into the isolator. Levels of humidity and sterilant gas are selected to avoid condensation of either within the isolator. In an embodiment, a positive pressure is maintained throughout the sterilization process.
1 . A method of treating a chamber, comprising:
humidifying the chamber to a non-condensing relative humidity;
injecting into the chamber a sterilant gas having a boiling point less than 50° C. to a non-condensing sterilant gas concentration;
recirculating the sterilant gas through the chamber for a selected treatment period; and
purging the sterilant gas from the chamber.
2 . A method as in claim 1 , wherein during the treating, a positive pressure is maintained relative to ambient pressure outside the chamber.
3 . A method as in claim 1 , wherein during the treating, temperature in the chamber is maintained between 10° C. and 50° C.
4 . A method as in claim 1 , wherein the concentration of sterilant gas is selected to be sufficient to sterilize the chamber in less than 100 minutes.
5 . A method as in claim 4 , wherein the concentration of sterilant gas is selected to be sufficient to sterilize the chamber in less than 20 minutes.
6 . A method as in claim 1 , wherein the concentration of sterilant gas is controlled by controlling a duration of the injecting.
7 . A method as in claim 1 , wherein the concentration of sterilant gas is controlled by controlling a duration of the injecting the sterilant into a pre-chamber in fluid communication with the chamber.
8 . A method as in claim 1 , wherein relative humidity is maintained between 70 and 85% relative humidity.
9 . A method as in claim 1 , wherein relative humidity is maintained between 55 and 70% relative humidity.
10 . A method as in claim 1 , wherein the purging comprises injecting gas free of sterilant.
11 . A method as in claim 1 , wherein the purging comprises recirculating the chamber gas through a sterilant-removing filter.
12 . A method as in claim 10 , wherein a rate of injecting of sterilant-free gas is selected such that the concentration of sterilant gas is reduced to less than 1 ppm in 30 minutes.
13 . A method as in claim 11 , wherein a rate of exchanging the gas in the chamber by recirculation through a sterilant-removing filter is selected such that the concentration of sterilant gas is reduced to less than 1 ppm in 30 minutes.
14 . A method of removing the sterilant from the chamber, as in claim 10 , wherein the flow rate is greater than 0.5 times the chamber volume per minute.
15 . A method of removing the sterilant from the chamber by injecting or recirculating air, as in claim 10 , wherein the air is controlled to be below 40% RH.
16 . A method as in claim 1 , wherein the sterilant gas is NO 2 .
17 . A method as in claim 1 , wherein the sterliant gas concentration is controlled by measuring pressure of the gas in a pre-chamber having a known volume and being in fluid communication with the chamber.