US3707398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing a pre-coat filter
Assignee: Stella Meta Filters Ltd
•
Filing: 1971-03-08
•
Granted: 1972-12-26
•
Expires: 1991-03-08
Abstract
Abstract THE INVENTION PROVIDES A METHOD OF PREPARING A PRECOAT FILTER FOR USE IN APPLICATIONS WHERE SILICA-CONTAINING FILTER MEDIA CANNOT BE EMPLOYED. IN THE METHOD A PRECOAT FILTER IS PROVIDED WITH A FIRST LAYER OF A FINELY-DIVIDED NON-FIBROUS INERT MATERIAL AND A SECOND LAYER OF A FIBROUS FILTER MEDIUM. IN OPERATION OF THE FILTER THE NON-FIBROUS INERT MATERIAL PREVENTS FOULING OF THE FILTER BY THE FIBROUS FILTER MEDIUM.
Inventors
- 👤 David Charlesworth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 01:37
CPC Classifications
B; B01; B01J; B01J20/00; B01J20/22; B01D; B01D37/00; B01D37/02
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |