US4213768A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nondestructive testing of HEPA filters
Assignee: Individual
•
Filing: 1978-11-27
•
Granted: 1980-07-22
•
Expires: 1998-11-27
Abstract
Abstract Method is provided for non-destructively testing the integrity of a high efficiency particulate air filters using conventional equipment with a novel testing medium comprising an aerosol of hydrophobic-surfaced particles, which is non-toxic, efficient in measuring filter integrity, unaffected by moisture and temperature conditions and non-coating of optics used in measuring, whereby more accurate measuring of HEPA filter condition is realized.
Inventors
- 👤 Albert J. Bauman
- 👤 Frank A. Morelli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:16
CPC Classifications
B; B01; B01D; B01D46/00; B01D46/54; B01D39/00; B01D39/14; B01D46/10; B01D46/52; B01D46/521; B01D2273/00; B01D2273/18; B01D2279/00; B01D2279/50; B01D2279/51
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
121 words
Method of non-destructively testing the integrity of a high efficiency particulate air filter having a frame and a filter pack sealed in the frame, said filter pack comprising a tightly packed axially extended alternating series of separators and parallel reverse turns of glass cloth along which a liquid tends to wick; said method including generating an aerosol in a gas stream of solid particles free of said liquid and having a hydrophobic surface and a mean average diameter of not more than 0.2 micron, exposing the filter to be tested to said aerosol under predetermined test conditions including a temperature at which said particles remain solid, and a pressure differential across the filter urging said gas stream aerosol through the filter.
Claim 2
Dependent Claim
121 words
Method of non-destructively testing the integrity of a high efficiency particulate air filter having a frame and a filter pack sealed in the frame, said filter pack comprising a tightly packed axially extended alternating series of separators and parallel reverse turns of glass cloth along which a liquid tends to wick; said method including generating an aerosol in a gas stream of solid particles free of said liquid and having a hydrophobic surface and a mean average diameter of not more than 0.2 micron, exposing the filter to be tested to said aerosol under predetermined test conditions including a temperature at which said particles remain solid, and a pressure differential across the filter urging said gas stream aerosol through the filter.
Claim 3
Dependent Claim
26 words
Method according to claim 1 in which said solid particles comprise silica, and including also maintaining a hydrophobic coating material on said silica particles during testing.
Claim 4
Dependent Claim
18 words
Method according to claim 1 including dispersing said particles in an inert gas stream to generate said aerosol.
Claim 5
Dependent Claim
21 words
Method according to claim 1 including also coating a hydrophilic particle with a hydrophobic coating, and thereafter generating an aerosol thereof.
Claim 6
Dependent Claim
26 words
Method according to claim 1 including also, coating a silica particle with an organosilane or more than 4 carbon atoms, and thereafter generating said aerosol thereof.
Claim 7
Dependent Claim
30 words
Method according to claim 1 including also, coating a fumed silica with a hydrophobic coating comprising an organosilane of more than 4 carbon atoms, and thereafter generating said aerosol thereof.
Claim 8
Dependent Claim
15 words
Method according to claim 6 in which said silica particle is coated with stearyl silane.
Claim 9
Dependent Claim
15 words
Method according to claim 6 in which said silica particle is coated with tert-butyl silane.
Claim 10
Dependent Claim
47 words
Method of generating an aerosol for non-destructive testing of a HEPA filter including coating silica particles having a mean average diameter of not more than 0.2 microns with an organosilane of more than 4 carbon atoms, and thereafter dispersing said silica particles in an inert gas stream.
Claim 11
Dependent Claim
47 words
Method of generating an aerosol for non-destructive testing of a HEPA filter including coating silica particles having a mean average diameter of not more than 0.2 microns with an organosilane of more than 4 carbon atoms, and thereafter dispersing said silica particles in an inert gas stream.
References Cited (Backward Citations)
US2848421A
Cited
US3438179A
Cited
US3395514A
Cited
US3853989A
Cited
US3757499A
Cited
US3960001A
Cited
US4055075A
Cited
US4132536A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-07-22 | 1984-01-21 | 1984-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-22 | 1988-01-21 | 1988-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-22 | 1992-01-21 | 1992-07-22 | $7700.00 | Window Closed / Lapsed |