VAPORIZED HYDROGEN PEROXIDE DECONTAMINATION SYSTEM WITH CONCENTRATION ADJUSTMENT MODE

• US 20080267818A1
• Filed: 04/27/2007
• Published: 10/30/2008
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: Steris Inc (Steris Corporation)
• Inventors: Hill, Aaron L.
• Granted Patent: US 7,919,059 B2
• Time in Patent Office: Days
• US Class Current: 422/28
• CPC Class Codes: A61L 2/208 Hydrogen peroxide
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation
• CPC Class Codes: A61L 2202/122 Chambers for sterilisation
• CPC Class Codes: A61L 2202/14 Means for controlling sterilisation processes, data processing, presentation and storage means, e.g. sensors, controllers, programs

Abstract

A decontamination system for decontaminating a region with a vaporized decontaminant, such as vaporized hydrogen peroxide. The concentration of the vaporized decontaminant within the region is modified in response to operating conditions. The decontamination system adjusts the concentration of the vaporized decontaminant in response to the monitored saturation concentration of the decontaminant, thereby preventing condensation of the vaporized decontaminant during a decontamination cycle. The decontamination system also adjusts the concentration of the vaporized decontaminant in order to minimize the time required to complete a successful decontamination operation.

Claims

1. A method for decontaminating a region with a vaporized decontaminant, the method comprising the steps of:

establishing a first concentration level of the vaporized decontaminant and a first exposure time associate with the first concentration level;

injecting the vaporized decontaminant into the region at an injection rate for obtaining the first concentration level of the vaporized decontaminant in the region;

monitoring the actual concentration of the vaporized decontaminant in the region;

determining the dew point concentration of the vaporized decontaminant in the region;

determining a dew point margin indicative of whether the actual concentration of the vaporized decontaminant in the region is at least a predetermined amount below the dew point concentration of the vaporized decontaminant in the region; and

modifying the injection rate if the actual concentration of the vaporized decontaminant in the region is not at least the predetermined amount below the dew point concentration of the vaporized decontaminant in the region.

2. A method according to claim 1, wherein said first concentration level and said associated first exposure time are established by inputting into a controller the first concentration level and the associated first exposure time.

3. A method according to claim 1, wherein said first concentration level and said associated exposure time are established by inputting into a controller a first concentration level and a D-value indicative of a desired reduction of bioburden.

4. A method according to claim 1, wherein said step of modifying the injection rate includes the step of:

reducing the injection rate to obtain a second concentration level of the vaporized decontaminant within the region, wherein a second exposure time is associated with the second concentration level.

5. A method according to claim 1, wherein said method further comprises:

initiating a first timer when the actual concentration of the vaporized decontaminant in the region reaches the first concentration level, wherein the first timer indicates the total time that the actual concentration of the vaporized decontaminant in the region is at or above the first concentration level; and

initiating a second timer when the actual concentration of the vaporized decontaminant in the region reaches a second concentration level, wherein a second exposure time is associated with the second concentration level, said second timer indicating the total time that the actual concentration of the vaporized decontaminant in the region is at or above the second concentration level;

determining a first time value indicative of the amount of time remaining until the first timer reaches the first exposure time;

determining a second time value indicative of the amount of time remaining until the second timer reaches the second exposure time; and

injecting vaporized decontaminant into the region at an injection rate for obtaining one of said first and second concentration levels based upon the shorter of the first and second time values.

6. A method according to claim 1, wherein said step of modifying the injection rate includes the step of reducing the injection rate to zero.

7. A method according to claim 1, wherein said method further comprises:

initiating at least one of an audible or visual indicator signal if the actual concentration of the vaporized decontaminant in the region is not at least the predetermined amount below the dew point concentration of the vaporized decontaminant in the region.

8. A method according to claim 1, wherein said step of determining whether the actual concentration of the vaporized decontaminant in the region is at least a predetermined amount below the dew point concentration of the vaporized decontaminant in the region, includes the steps of:

establishing a dew point margin indicative of the minimum acceptable difference between;

(1) actual concentration of the vaporized decontaminant in the region and (2) dew point concentration for the vaporized decontaminant in the region;

determining a measured delta value indicative of the difference between the actual concentration of the vaporized decontaminant and the dew point concentration for the vaporized decontaminant; and

comparing the measured delta value to the dew point margin.

9. A method according to claim 1, wherein said method further comprises:

generating said vaporized decontaminant from an aqueous solution of hydrogen peroxide.

10. A method according to claim 9, wherein said aqueous solution of hydrogen peroxide is about 30% to 59% hydrogen peroxide by weight.

11. A method according to claim 1, wherein said actual concentration of the vaporized decontaminant in the region is monitored by a plurality of decontaminant concentration sensors, wherein the dew point margin is determined using data from the decontaminant concentration sensor indicating the highest actual concentration of the vaporized decontaminant in the region.

12. A method according to claim 1, wherein said actual concentration of the vaporized decontaminant in the region is monitored by a plurality of decontaminant concentration sensors, wherein data from the concentration sensor indicating the lowest actual concentration of the vaporized decontaminant is used to determine an elapsed exposure time associated with the vaporized decontaminant in the region.

13. A method according to claim 1, wherein humidity is monitored in the region by a plurality of humidity sensors, said dew point concentration determined using data from the humidity sensor indicative of the lowest dew point concentration.

14. A method for decontaminating a region with a vaporized decontaminant, the method comprising the steps of:

establishing a first concentration level of the vaporized decontaminant and a first exposure time associate with the first concentration level;

establishing a second concentration level of the vaporized decontaminant and a second exposure time associated with the second concentration level, wherein the second concentration level is greater than the first concentration level;

initiating a first timer when the actual concentration of the vaporized decontaminant in the region reaches the first concentration level, wherein the first timer indicates the total elapsed time that the actual concentration of the vaporized decontaminant in the region is at or above the first concentration level; and

initiating a second timer when the actual concentration of the vaporized decontaminant in the region reaches the second concentration level, wherein the second timer indicates the total elapsed time that the actual concentration of the vaporized decontaminant in the region is at or above the second concentration level;

determining a first time value indicative of the amount of time remaining until the first timer reaches the first exposure time;

determining a second time value indicative of the amount of time remaining until the second timer reaches the second exposure time; and

injecting vaporized decontaminant into the region at an injection rate for obtaining one of said first and second concentration levels based upon the difference between the first and second time values.

15. A method according to claim 14, wherein said method further comprises:

injecting vaporized decontaminant into the region at an injection rate for obtaining the first concentration level if said first time value is equal to or less than said second time value.

16. A method according to claim 14, wherein said method further comprises:

generating said vaporized decontaminant from an aqueous solution of hydrogen peroxide.

17. A method according to claim 16, wherein said aqueous solution of hydrogen peroxide is about 30% to 59% hydrogen peroxide by weight.

18. A method according to claim 14, wherein said method further comprises:

monitoring the actual concentration of the vaporized decontaminant in the region;

determining the dew point concentration of the vaporized decontaminant in the region;

determining a dew point margin indicative of whether the actual concentration of the vaporized decontaminant in the region is at least a predetermined amount below the dew point concentration of the vaporized decontaminant in the region;

19. A method according to claim 18, wherein said actual concentration of the vaporized decontaminant in the region is monitored by a plurality of decontaminant concentration sensors, wherein the dew point margin is determined using data from the decontaminant concentration sensor indicating the highest actual concentration of the vaporized decontaminant in the region.

20. A method according to claim 18, wherein humidity is monitored in the region by a plurality of humidity sensors, said dew point concentration is determined using data from the humidity sensor indicative of the lowest dew point concentration.

21. A method according to claim 14, wherein said actual concentration of the vaporized decontaminant in the region is monitored by a plurality of decontaminant concentration sensors, wherein data from the decontaminant concentration sensor indicating the lowest actual concentration of the vaporized decontaminant is used to determine a total elapsed exposure time associated with the vaporized decontaminant in the region.

22. A vapor decontamination system for decontaminating a region, said system comprising:

a generator for generating a vaporized decontaminant;

a circulating system for supplying said vaporized decontaminant to said region;

at least one humidity sensor providing a first signal indicative of moisture in the region;

a temperature sensor providing a second signal indicative of the temperature in the region;

at least one concentration sensor providing a third signal indicative of the concentration of the decontaminant in the region;

input means for inputting into a controller one of;

(a) a first concentration level and a first exposure time associated therewith, or (b) a first concentration level and a D-value indicative of a desired reduction of bioburden, wherein a first exposure time associated with the first concentration level is determined according to the D-value,

a controller communicating with said generator to control the rate at which vaporized decontaminant is injected into the region, and receiving the first, second, and third signal, said controller operable to;

inject the vaporized decontaminant into the region at an injection rate for obtaining the first concentration level of vaporized decontaminant in the region;

monitor the actual concentration of the vaporized decontaminant in the region;

determine the dew point concentration of the vaporized decontaminant in the region; and

determine a dew point margin indicative of whether the actual concentration of the vaporized decontaminant in the region is at least a predetermined amount below the dew point concentration of the vaporized decontaminant in the region.

23. A vapor decontamination system according to claim 22, wherein said controller is her operable to:

modify the injection rate if the actual concentration of the vaporized decontaminant in the region is not at least the predetermined amount below the dew point concentration of the vaporized decontaminant in the region.

24. A system according to claim 23, wherein said controller modifies the injection rate by reducing the injection rate to obtain a second concentration level of the vaporized decontaminant within the region, wherein a second exposure time is associated with the second concentration level.

25. A system according to claim 22, wherein said controller is further operable to:

initiate a first timer when the actual concentration of the vaporized decontaminant in the region reaches the first concentration level, wherein the first timer indicates the total time that the actual concentration of the vaporized decontaminant in the region is at or above the first concentration level; and

initiate a second timer when the actual concentration of the vaporized decontaminant in the region reaches a second concentration level, wherein a second exposure time is associated with the second concentration level, the second timer indicating the total time that the actual concentration of the vaporized decontaminant in the region is at or above the second concentration level;

determine a first time value indicative of the amount of time remaining until the first timer reaches the first exposure time;

determine a second time value indicative of the amount of time remaining until the second timer reaches the second exposure time; and

inject vaporized decontaminant into the region at an injection rate for obtaining one of said first and second concentration levels based upon the shorter of the first and second time values.

26. A system according to claim 22, wherein said controller modifies the injection rate by reducing the injection rate to zero.

27. A system according to claim 22, wherein said system further comprises:

at least one of an audible indicator or a visual indicator, said indicator being activated by said controller if the actual concentration of the vaporized decontaminant in the region is not at least the predetermined amount below the dew point concentration of the vaporized decontaminant in the region.

28. A system according to claim 22, wherein said controller determines whether the actual concentration of the vaporized decontaminant in the region is at least a predetermined amount below the dew point concentration of the vaporized decontaminant in the region by:

establishing a dew point margin indicative of the minimum acceptable difference between;

(1) actual concentration of the vaporized decontaminant in the region and (2) dew point concentration for the vaporized decontaminant in the region;

determining a measured delta value indicative of the difference between the actual concentration of the vaporized decontaminant and the dew point concentration for the vaporized decontaminant; and

comparing the measured delta value to the dew point margin.

29. A system according to claim 22, wherein said vaporized decontaminant is generated from an aqueous solution of hydrogen peroxide.

30. A system according to claim 22, wherein said system comprises a plurality of concentration sensors indicating the concentration of the decontaminant in the region, wherein the dew point margin is determined using data from the decontaminant concentration sensor indicating the highest concentration of the vaporized decontaminant in the region.

31. A system according to claim 22, wherein said system comprises a plurality of concentration sensors indicating the concentration of the decontaminant in the region, wherein data from the concentration sensor indicating the lowest concentration of the decontaminant is used by said controller to determine an elapsed exposure time associated the vaporized decontaminant in the region.

32. A system according to claim 22, wherein said system comprises a plurality of humidity sensors, said controller determining the dew point concentration using data from the humidity sensor indicative of the lowest dew point concentration.