Filter integrity tester
View Patent ↗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.
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 an adsorbent filter;
detecting the existence and concentration of the vapor in an outlet air stream from the filter, the detecting step including:
collecting a portion of the vapor from said outlet air stream from said filter;
generating a volume of clean air,
enriching a portion of said volume of clean air with said collected hydrophilic test chemical; 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 temperature.
5. The method of claim 1 , wherein said detecting step further includes the steps of detecting an amount and a mass of said hydrophilic test chemical collected.
6. The method of claim 1 , 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 6 , wherein said enriching step further includes the steps of:
heating said chemical sampling member allowing said collected sampled hydrophilic test chemical to desorb into a gas phase while passing a stream of clean air through said chemical sampling member in a second direction countercurrent 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 7 , 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 8 , 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 a mass of said hydrophilic test chemical.
10. The method of claim 9 , wherein the collecting step further includes integrating a mass of said injected hydrophilic test chemical, and the determining step includes comparing the detected mass of said hydrophilic test chemical with said integrated mass of said hydrophilic test chemical.
11. The method of claim 6 , wherein the collecting step further includes removing particulates and low-volatility chemicals from said portion of said outlet air stream prior to passing said air stream through said chemical sampling member.