Method of decontaminating a chamber that has movable shelves

• US 5,389,336 A
• Filed: 01/13/1994
• Issued: 02/14/1995
• Est. Priority Date: 02/04/1993
• Status: Expired due to Fees

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: American Sterilizer Company (Steris Corporation)
• Inventors: Childers, Robert W.
• Primary Examiner(s): Warden, Robert J.
• Assistant Examiner(s): JASTRZAB, KRISANNE MARIE
• Application Number:
  US08/181,640
• Time in Patent Office: 397 Days
• Field of Search: 422/28, 422/33, 422/292, 422/295, 422/297, 422/302, 108/92, 108/93, 108/96
• US Class Current: 422/28
• CPC Class Codes: A61L 2/20 Gaseous substances, e.g. vapours

Abstract

A method of decontaminating or sterilizing chamber systems including freeze dryers at low temperature and pressure levels by utilizing vaporized sterilant, preferably hydrogen peroxide, peracetic acid and mixtures thereof is disclosed.

Claims

1. A method for decontaminating a chamber system to a predetermined level, that comprises the steps of:

a) providing a chamber system having at least a lower and an upper shelf, at least one of which is vertically movable while maintaining its horizontal position, a condenser, and piping that are fluidly connected to each other and to a vacuum system;

b) placing at least one container containing a predetermined amount of liquid sterilant into the chamber on at least one shelf;

c) placing a loose fitting cap on said at least one container;

d) moving one of the shelves until the adjacent shelf presses against the at least one container cap thereby sealing the container;

e) evacuating the chamber, condenser and piping to a vacuum of predetermined subatmospheric absolute pressure, wherein the chamber system is isolated from the vacuum system;

f) moving another of said movable shelves until the cap on the at least one container is no longer sealed on the container;

g) vaporizing at least a portion of said liquid sterilant by exposing said liquid sterilant to the evacuated chamber environment; and

h) maintaining the vacuum and exposing the interior of said chamber to sterilant vapor for a predetermined time until a predetermined level of decontamination is achieved.

2. The method of claim 1, wherein the liquid sterilant in said container is selected from the group consisting of hydrogen peroxide and peracetic acid and mixtures thereof.

3. The method of claim 1, wherein the liquid sterilant in said container is from between about 30% to about 35% by weight concentration of aqueous hydrogen peroxide solution.

4. The method of claim 1, wherein the mass of liquid sterilant is small compared to the mass of the container to prevent freezing.

5. The method of claim 1, wherein the predetermined level of decontamination is sterilization.

6. The method of claim 1, wherein the chamber system is a freeze dryer system.

7. The method of claim 1, wherein the method further comprises repeating steps d) through h) for each additional shelf until a predetermined level of decontamination is achieved.

8. A method for decontaminating a chamber system that comprises the steps of

a) providing a chamber system having a bottom, at least one middle and a top shelf, wherein at least two of the shelves are vertically movable while maintaining a horizontal position and which can be stopped in any position, a condenser, and piping that are fluidly connected to each other and to a vacuum system;

b) placing multiple containers containing a predetermined amount of liquid sterilant into the chamber on at least two of the shelves each of which is directly below and adjacent to one of the other shelves;

c) placing a loose fitting cap on each container;

d) selectively moving each movable shelf to press the caps and seal the containers on an adjacent shelf;

e) evacuating the chamber, condenser and piping to a vacuum of a first predetermined subatmospheric absolute pressure, wherein the chamber system is isolated from the vacuum system;

f) moving at least one of the movable shelves until the cap on each container on a respective adjacent shelf is released and the container is no longer sealed;

g) vaporizing the liquid sterilant in each non-sealed container by exposing the liquid to the evacuated chamber;

h) maintaining the vacuum and exposing the interior of the chamber to sterilant vapor for a first predetermined time;

i) venting air into the chamber, thereby raising the pressure within the chamber to a second predetermined subatmospheric absolute pressure;

j) evacuating the chamber, condenser and piping to a vacuum of a third predetermined subatmospheric absolute pressure, wherein the chamber system is isolated from the vacuum system;

k) moving at least a second one of the movable shelves until the cap on each container on a respective adjacent shelf is released and the container is no longer sealed;

i) vaporizing the liquid sterilant in each non-sealed container by exposing the liquid to the evacuated chamber environment; and

m) maintaining the vacuum and exposing the interior of said chamber to sterilant vapor for a second predetermined time until a predetermined level of decontamination is achieved.

9. The method of claim 8, wherein the liquid sterilant is selected from the group consisting of hydrogen peroxide and peracetic acid and mixtures thereof.

10. The method of claim 8, wherein the liquid sterilant is from between about 30% to about 35% by weight concentration of aqueous hydrogen peroxide solution.

11. The method of claim 8, wherein the predetermined amount of liquid sterilant is distributed among the containers placed on the chamber shelves.

12. The method of claim 8, wherein the predetermined level of decontamination is sterilization.

13. The method of claim 8, wherein the chamber system is a freeze dryer system.

14. A method of decontaminating a chamber system, which comprises the steps of:

a) providing a chamber system having a plurality of shelves, at least one of which is vertically movable while maintaining its horizontal position, a condenser, and piping that are fluidly connected to each other and to a vacuum system;

b) placing n sets of containers, each set consisting of at least one container, into the chamber on at least one of the shelves, each container containing a predetermined amount of liquid sterilant, and wherein each container further comprises a cap assembly, a compression spring, a plunger, a sealing device, and a bottom assembly such that each set has a cap assembly of a different length;

c) placing the cap assembly loosely on each container;

d) moving the movable shelves until the cap assembly on each container is pressed by one of the respective adjacent shelves and seals substantially all of the containers;

e) evacuating the chamber, condenser and piping to a vacuum of a predetermined subatmospheric absolute pressure, wherein the chamber system is isolated from the vacuum system;

f) moving at least one of the movable shelves to a first predetermined level until the cap assembly is released and the seal on at least one of the containers is broken;

g) vaporizing the liquid sterilant by exposing said liquid to the evacuated chamber environment;

h) maintaining the vacuum and exposing the interior of the chamber system to sterilant vapor for a first predetermined time;

i) injecting air into the chamber;

j) re-evacuating the chamber, condenser and piping;

k) moving at least another movable shelf to another predetermined level until the cap assembly is released and the seal of at least one additional container is broken;

l) vaporizing the liquid sterilant by exposing said liquid to the evacuated chamber environment;

m) maintaining the vacuum and exposing the interior of the chamber system to sterilant vapor for another predetermined time; and

n) maintaining the vacuum and exposing the interior of the chamber system to sterilant vapor until a predetermined level of decontamination is achieved.

15. The method of claim 14, wherein the bottom assembly of said containers has raised dimples permitting the area on the shelf below the containers to be sterilized.

16. The method of claim 14, wherein the liquid sterilant is selected from the group consisting of hydrogen peroxide and peracetic acid and mixtures thereof.

17. The method of claim 14, wherein the liquid sterilant is from between about 30% to about 35% by weight concentration of aqueous hydrogen peroxide solution.

18. The method of claim 14, wherein the predetermined level of decontamination is sterilization.

19. The method of claim 14, wherein the chamber system is a freeze dryer system.

20. The method of claim 14, wherein the liquid sterilant in each container is about 1 to about 2 grams of liquid hydrogen peroxide.

21. The method of claim 14, wherein the number of sets of containers, n, is any number between 2 and 20 and in which steps (e) through (g) are repeated once for each set of containers.

22. The method of claim 14, wherein the method further comprising repeating steps k) through m) until a predetermined level of decontamination is achieved.