Method and apparatus for measuring chemical concentration in a fluid

• US 6,844,742 B2
• Filed: 03/14/2003
• Issued: 01/18/2005
• Est. Priority Date: 03/14/2003
• Status: Expired due to Term

• Current Assignee: Steris Corporation
• Original Assignee: Steris Corporation
• Inventors: Centanni, Michael A.
• Primary Examiner(s): Deb, Anjan
• Assistant Examiner(s): He, Amy
• Application Number:
  US10/389,036
• Publication Number:
  US 20040178802A1
• Time in Patent Office: 676 Days
• Field of Search: 204/403.01, 204/416, 204/431, 205/775, 205/777, 205/778.5, 205/782, 205/789, 422/82.01, 422/28, 324/666, 324/664, 324/663, 324/658, 324665-668, 324686-689, 324/610, 324/673, 324/680
• US Class Current: 324/662
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26

Abstract

A chemical concentration detecting system for determining the relative concentrations of a multiple component chemical solution. The multi-component solution is preferably comprised of an antimicrobial chemical and a base fluid that acts as a diluent for the antimicrobial chemical, or as a vehicle or carrier for the antimicrobial chemical. A capacitor is exposed to the decontamination solution, wherein the decontamination solution acts as the dielectric between the plates of the capacitor. Permittivity of the dielectric is affected by the relative concentrations of the components, and thus a measurement of the capacitance is used to determine the relative concentration levels of the components in the solution.

Claims

1. A chemical concentration detecting system for determining a concentration of an antimicrobial chemical component in a multi-component decontamination solution comprised of the antimicrobial chemical component and a base fluid, said system comprising:

a capacitor having first and second plates exposed to the decontamination solution, said decontamination solution comprising a dielectric therebetween; and

processing means for determining a sensed electrical properly value of the capacitor, said sensed electrical property value varying according to the concentration of the antimicrobial chemical component in the decontamination solution,

wherein said antimicrobial chemical component is selected from a group consisting of;

hydrogen peroxide, peracid, peracetic acid, bleach, ozone, ammonia, ethylene oxide, a fluorine containing chemical, and a chlorine containing chemical.

2. A chemical concentration detecting system according to claim 1, wherein said capacitor is selected from the group consisting of:

a parallel plate capacitor, a cylindrical capacitor, and a spherical capacitor.

3. A chemical concentration detecting system according to claim 1, wherein said processing means includes a memory for storing a set of data including electrical property values and corresponding concentration values indicative of the relative concentration of the antimicrobial chemical component in the decontamination solution.

4. A chemical concentration detecting system according to claim 3, wherein said processing means uses the sensed electrical property value to obtain a relative concentration from said set of data.

5. A chemical concentration detecting system according to claim 4, wherein said processing means normalizes said relative concentration to provide an absolute concentration of the antimicrobial chemical component of the decontamination solution.

6. A chemical concentration detecting system according to claim 3, wherein said processing means uses said set of data to interpolate or extrapolate a relative concentration corresponding to the sensed electrical property value.

7. A chemical concentration detecting system according to claim 1, wherein said antimicrobial chemical component is hydrogen peroxide.

8. A chemical concentration detecting system according to claim 7, wherein said antimicrobial chemical is selected from a group consisting of:

a liquid and an oxidative gas.

9. A chemical concentration detecting system according to claim 1, wherein said base fluid is at least one of:

(a) a diluent for the antimicrobial chemical component, and (b) a vehicle for the antimicrobial chemical component.

10. A chemical concentration detecting system according to claim 1, wherein said antimicrobial chemical component is peracid.

11. A chemical concentration detecting system according to claim 1, wherein said antimicrobial chemical component is peracetic acid.

12. A chemical concentration detecting system according to claim 1, wherein said system further comprises:

a bridge circuit, wherein said capacitor forms a part of said bridge circuit.

13. A chemical concentration detecting system according to claim 12, wherein said bridge circuit includes a potentiometer having first and second resistances associated therewith, said processing means determining values of said first and second resistances when the bridge circuit is in a null condition to determining said sensed electrical property value.

50. A chemical concentration detecting system according to claim 1, wherein said base fluid is selected from a group consisting of:

water, an alcohol, a glycol containing chemical compound thereof.

51. A chemical concentration detecting system according to claim 50, wherein said glycol-containing chemical compound is selected from a group consisting of:

polyethylene glycol, diethylene glycol triethylene glycol, tetraethylene glycol, glycol ethers, polypropylene glycol, propylene glycol, and combinations thereof.

52. A chemical concentration detecting system according to claim 50, wherein said alcohol is a tertiary alcohol.

14. A method for determining a concentration of an antimicrobial chemical component in a multi-component decontamination solution composed of the antimicrobial chemical component and a base fluid, the method comprising the steps of:

exposing a capacitor, having first and second plates, to the decontamination solution, said decontamination solution comprising a dielectric therebetween;

sensing an electrical property of the capacitor to obtain a sensed electrical property value, said sensed electrical property value varying according to the concentration of the antimicrobial chemical component in the decontamination solution; and

determining the concentration of the antimicrobial chemical component in accordance with said sensed electrical property value,

wherein said antimicrobial chemical component is selected from a group consisting of;

hydrogen peroxide, peracid, peracetic acid, bleach, ozone, ammonia, ethylene oxide, a fluorine containing chemical, and a chlorine containing chemical.

15. A method according to claim 14, wherein said step of determining the concentration of the antimicrobial chemical component in accordance with said sensed electrical property value includes:

accessing pre-stored data including electrical property values and corresponding concentration values indicative of the concentration of the antimicrobial chemical component in the decontamination solution.

16. A method according to claim 15, wherein said step of determining the concentration of the antimicrobial chemical component in accordance with said sensed electrical property value includes:

interpolating or extrapolating from the pre-stored data the concentration of the antimicrobial chemical component in the decontamination solution.

17. A method according to claim 15, wherein said step of determining the concentration of the antimicrobial chemical component in accordance with said sensed electrical property value includes:

normalizing said concentration of the antimicrobial chemical component to provide an absolute concentration of the antimicrobial chemical component of said decontamination solution.

18. A method according to claim 14, wherein said antimicrobial chemical component is hydrogen peroxide.

19. A method according to claim 14, wherein said base fluid is at least one of:

(a) a diluent for the antimicrobial chemical component, and (b) a vehicle for the antimicrobial chemical component.

20. A method according to claim 14, wherein said antimicrobial chemical component is peracid.

21. A method according to claim 14, wherein said antimicrobial chemical component is peracetic acid.

22. A method according to claim 14, wherein said base fluid is selected from a group consisting of:

water, an alcohol, a glycol-containing chemical compound, and combinations thereof.

23. A method according to claim 22, wherein said glycol-containing chemical compound is selected for a group consisting of:

polyethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, glycol ethers, polypropylene glycol, propylene glycol, and combinations thereof.

24. A method according to claim 22, wherein said alcohol is a tertiary alcohol.

25. A method for determining a concentration of an antimicrobial chemical component in a multi-component decontamination solution comprised of the antimicrobial chemical component and a base fluid, the method comprising the steps of:

exposing a capacitor, having first and second plates, to the decontamination solution, said decontamination solution comprising a dielectric therebetween;

sensing an electrical property of the capacitor to obtain a sensed electrical property value, said sensed electrical property value varying according to the concentration of the antimicrobial chemical component in the decontamination solution;

accessing pre-stored data including electrical property values and corresponding concentration values indicative of the concentration of the antimicrobial chemical component in the decontamination solution; and

determining the concentration of the antimicrobial chemical component in accordance with said pre-stored data.

26. A method according to claim 25, wherein said step of determining the concentration of the antimicrobial chemical component in accordance with said pre-stored data includes:

interpolating or extrapolating from the pre-stored data the concentration of the antimicrobial chemical component in the decontamination solution.

27. A method according to claim 25, wherein said step of determining the concentration of the antimicrobial chemical component in accordance with said pre-stored data includes:

normalizing said concentration of the antimicrobial chemical component to provide an absolute concentration of the antimicrobial chemical component of said decontamination solution.

28. A method according to claim 25, wherein said antimicrobial chemical component is selected from a group consisting of:

hydrogen peroxide, peracid, peracetic acid, bleach, ozone, ammonia, ethylene oxide, a fluorine containing chemical, and a chlorine containing chemical.

29. A method according to claim 25, wherein said base fluid is at least one of:

(a) a diluent for the antimicrobial chemical component, and (b) a vehicle for the antimicrobial chemical component.

30. A method according to claim 25, wherein said base fluid is selected from a group consisting of:

water, an alcohol, a glycol-containing chemical compound, and combinations thereof.

31. A method according to claim 30, wherein said glycol-containing chemical compound is selected from a group consisting of:

polyethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, glycol ethers, polypropylene glycol, propylene glycol, and combinations thereof.

32. A method according to claim 30, wherein said alcohol is a tertiary alcohol.

33. A chemical concentration detecting system for determining a concentration of an antimicrobial chemical component in a multi-component decontamination solution comprised of the antimicrobial chemical component and a base fluid, said system comprising:

a capacitor having fist and second plates exposed to the decontamination solution, said decontamination solution comprising a dielectric therebetween;

processing means for determining a sensed electrical property value of the capacitor, said sensed electrical properly value varying according to the concentration of the antimicrobial chemical component in the decontamination solution; and

a memory for storing a set of data including electrical property values and corresponding concentration values indicative of the relative concentration of the antimicrobial chemical component in the decontamination solution.

34. A chemical concentration detecting system according to claim 33, wherein said antimicrobial chemical component is selected from a group consisting of:

hydrogen peroxide, peracid, peracetic acid, bleach, ozone, ammonia, ethylene oxide, a fluorine containing chemical, and a chlorine containing chemical.

35. A chemical concentration detecting system according to claim 33, wherein said antimicrobial chemical component is hydrogen peroxide.

36. A chemical concentration detecting system according to claim 33, wherein said antimicrobial chemical component is peracid.

37. A chemical concentration detecting system according to claim 33, wherein said antimicrobial chemical component is peracetic acid.

38. A chemical concentration detecting system according to claim 33, wherein said base fluid is at least one of:

(a) a diluent for the antimicrobial chemical component, and (b) a vehicle for the antimicrobial chemical component.

39. A method according to claim 33, wherein said base fluid is selected from a group consisting of:

water, an alcohol, a glycol-containing chemical compound, and combinations thereof.

40. A chemical concentration detecting system according to claim 39, wherein said glycol-containing chemical compound is selected from a group consisting of:

polyethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, glycol ethers, polypropylene glycol, propylene glycol, and combinations thereof.

41. A chemical concentration detecting system according to claim 39, wherein said alcohol is a tertiary alcohol.

42. A chemical concentration detecting system according to claim 33, wherein said antimicrobial chemical is selected from a group consisting of:

a liquid and an oxidative gas.

43. A chemical concentration detecting system according to claim 33, wherein said capacitor is selected from the group consisting of:

a parallel plate capacitor, a cylindrical capacitor, and a spherical capacitor.

44. A chemical concentration detecting system according to claim 33, wherein said processing means uses the sensed electrical property value to obtain a relative concentration from said set of data.

45. A chemical concentration detecting system according to claim 33, wherein said processing means uses said set of data to interpolate or extrapolate a relative concentration corresponding to the sensed electrical property value.

46. A chemical concentration detecting system according to claim 45, wherein said processing means normalizes said relative concentration to provide an absolute concentration of the antimicrobial chemical component of the decontamination solution.

47. A chemical concentration detecting system according to claim 33, wherein said system further comprises:

a bridge circuit, wherein said capacitor forms a part of said bridge circuit.

48. A chemical concentration detecting system according to claim 47, wherein said bridge circuit includes a potentiometer having first and second resistances associated therewith, said processing means determining values of said first and second resistances when the bridge circuit is in a null condition to determine said sensed electrical property value.

49. A method for determining whether rinse water used during a decontamination process is devoid of an antimicrobial chemical component, said method comprising:

exposing a capacitor, having first and second plates, to the rinse water, said rinse water comprising a dielectric therebetween;

sensing an electrical property of the capacitor to obtain a sensed electrical property value, said sensed electrical property value varying according to the concentration of the antimicrobial chemical component in the rinse water; and

determining whether the sensed electrical property is indicative of the presence of an antimicrobial chemical component in the rinse water by accessing pre-stored data.