Filter integrity tester

• US 20060188994A1
• Filed: 02/23/2005
• Published: 08/24/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: HDT Tactical Systems, Inc. (HDT Global, Inc.)
• Original Assignee: Hunters Manufacturing Co Incorporated (Hunter's Manufacturing Company Incorporated)
• Inventors: Ding, Yuqing, Friday, David K., Shrewsbury, Mark
• Granted Patent: US 7,592,178 B2
• Time in Patent Office: Days
• US Class Current: 436/3
• CPC Class Codes: B01D 65/102 Detection of leaks in membranes

Abstract

An apparatus and method for testing the integrity of a filter under humid conditions is provided. The apparatus includes an injection assembly which is located on a first side of the filter and a detection assembly which is spaced from the injection assembly and located on a second side of the filter. The injection assembly injects a mixture of an air stream and a hydrophilic test chemical vapor of a known concentration through the filter. The injection assembly includes a sealed vaporizer which generates the mixture of the air stream and the hydrophilic test chemical vapor. The vaporizer includes a contact bed having an inert packing media for vaporizing the hydrophilic test chemical. The detection assembly detects a concentration peak of the hydrophilic test chemical vapor exiting the filter. The detection assembly includes a chemical sampling member, a chemical enriching member and a chemical detector. At least one micro-controller communicates with the injection assembly and the detection assembly for controlling same.

Claims

1. A method of testing filter integrity comprising:

vaporizing a hydrophilic test chemical in air to form a vapor;

injecting the vapor into an inlet air stream of a filter;

detecting the existence and concentration of the vapor in an outlet air stream from the filter; and

determining the existence and extent of a leak in the filter.

2. The method of claim 1, wherein said vaporizing step includes the steps of:

passing a pressurized air stream through a port;

mixing said air stream with said hydrophilic test chemical to form a mixture; and

passing the mixture through a contact bed having an inert packing media, said inert packing media being wetted with said hydrophilic test chemical.

3. The method of claim 2, further including the steps of:

saturating the mixture with the hydrophilic test chemical; and

mixing the saturated mixture with air to form the vapor.

4. The method of claim 3, further including the steps of:

compensating for a heat loss in said contact bed by constantly passing the mixture through the contact bed; and

maintaining said hydrophilic test chemical at a relatively constant predetermined temperature.

5. The method of claim 1, wherein said detecting step further includes the steps of:

collecting a portion of the vapor from said outlet air stream-from said filter;

enriching said collected hydrophilic test chemical; and

detecting an amount and a mass of said hydrophilic test chemical collected.

6. The method of claim 5, wherein said collecting step further includes the step of passing a portion of said outlet air stream in a first direction through a chemical sampling member having a hydrophobic adsorbent for collecting said hydrophilic test chemical.

7. The method of claim 5, wherein said enriching step further includes the steps of:

heating said chemical sampling member while passing a stream of air in a second direction counter current to said first direction; and

directing said stream of air through a chemical enriching member having a hydrophobic adsorbent for collecting said hydrophilic test chemical from an outlet of said chemical sampling member.

8. The method of claim 5, wherein said detecting step further includes the step of:

heating said chemical enriching member while passing a stream of clean air through said chemical enriching member;

directing an outlet air stream from said chemical enriching member into a gas chromatography column; and

,

detecting an outlet air stream from said gas chromatography column for chemicals including said hydrophilic test chemical.

9. The method of claim 5, wherein said detecting step further includes the step measuring a concentration of said hydrophilic test chemical, measuring a flow rate of said outlet air stream from said gas chromatography column and integrating an amount of a mass of said hydrophilic test chemical.

10. An apparatus for testing an integrity of an associated filter under humid conditions comprising:

an injection assembly for injecting a mixture of an air stream and a hydrophilic test chemical vapor of a known concentration through an associated filter, the injection assembly including a sealed vaporizer for generating said mixture of said air stream and said hydrophilic test chemical vapor, said vaporizer including a contact bed having an inert packing media for vaporizing said hydrophilic test chemical, said injection assembly being located on a first side of the associated filter;

a detection assembly for detecting a concentration peak of said hydrophilic test chemical vapor exiting the associated filter, the detection assembly including a chemical sampling member, a chemical enriching member and a chemical detector, said detection assembly being spaced from said injection assembly and being located on a second side of the associated filter; and

,

at least one micro-controller which communicates with said injection assembly and said detection assembly for controlling same.

11. The apparatus of claim 10, wherein said injection assembly includes:

a first air compressor for drawing a first stream of ambient air into and through said vaporizer; and

a hydrophilic test chemical reservoir.

12. The apparatus of claim 11, wherein said injection assembly further includes a second air compressor for driving a second stream of ambient air, said second stream of ambient air mixing with said mixture of said air stream and said hydrophilic test chemical vapor at an outlet of said vaporizer.

13. The apparatus of claim 11, wherein said vaporizer includes a port for generating said air stream and at least one liquid inlet opening located adjacent to said port, said inlet opening communicating with said reservoir.

14. The apparatus of claim 13, wherein said vaporizer further includes a cylindrical tubing having an inside diameter larger than an outside diameter of said port.

15. The apparatus of claim 10, wherein at least one of said chemical sampling member and said chemical enriching member of said detection assembly includes a temperature detector and a heating unit.

16. The apparatus of claim 10, wherein said detection assembly further includes a gas chromatography unit.

17. The apparatus of claim 10, wherein said detection assembly further includes:

a vacuum pump and at least one clean air port; and

,

a clean air generation unit for generating clean and dry air, said clean air generation unit including an air compressor and a reservoir.

18. The apparatus of claim 17, wherein said clean air generation unit further includes:

a first filter and a second filter, each filter including a first layer of an hydrophobic adsorbent and a second layer of hydrophilic adsorbent;

at least one three-way valve connecting said first filter and said second filter;

a particulate filter;

a pressure sensor for measuring the pressure in the reservoir; and

,

at least one regulator for regulating an outlet pressure of the clean and dry air.

19. The apparatus of claim 10, wherein said injection assembly includes a first radio frequency transmitter/receiver and said detection assembly includes a second radio frequency transmitter/receiver, said first and second radio frequency transmitters/receivers being in communication with said at least one micro-controller.

20. A method for detecting a concentration of a test chemical in an outlet air stream of a filter comprising the steps of:

injecting a predetermined mass of said test chemical into an inlet air stream of said filter;

sampling a volume of said outlet air stream from said filter, said outlet air stream including at least a portion of said predetermined mass of said test chemical;

enriching a second volume of air with said sampled test chemical;

heating said enriched second volume of air;

maintaining said second volume of air at a high temperature;

allowing said sampled test chemical in said second volume of air to desorb into a gas phase; and

,

detecting a mass of said sampled test chemical in said second volume of air.

21. The method of claim 20, further including the step of removing low-volatility chemicals from said sampled volume of said outlet air stream.

22. A method of calibrating the effectiveness of a filter integrity tester, the filter integrity tester having a detection assembly for detecting a concentration peak of a test chemical, the detection assembly including a chemical sampling member, a chemical enriching member and a chemical detector, the method comprising the steps of:

injecting a predetermined mass of said test chemical into said chemical sampling member;

sampling a volume of said test chemical;

enriching a second volume of air with said test chemical;

heating said enriched second volume of air;

maintaining said enriched second volume of air at a high temperature;

allowing said enriched test chemical in said second volume of air to desorb into a gas phase;

detecting a mass of said test chemical in second volume of air; and

,

comparing said detected mass of said test chemical with said predetermined mass of said test chemical.