US3814247A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of filtering
Assignee: Filtra-Systems Co
•
Filing: 1972-08-21
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Granted: 1974-06-04
•
Expires: 1992-08-21
Abstract
Abstract A liquid filtering method for operating an apparatus comprising a deep bed of dual, vertically separate, granular filter media beds. The first filter media bed has relatively coarse grains being in the size range of 0.050 to 0.375 inches - which have a specific gravity in the range of 0.9 to 1.6. The second filter media bed, which underlies the first bed, has finer grains which have a specific gravity greater than 2.1. Upon backwashing, the first bed is slurried and turbulently recirculated through a path external of the retaining vessel, while the second bed is only expanded. After backwashing, the filter media beds assume their original respective orientations.
Inventors
- 👤 G Hirs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:35
CPC Classifications
B; B01; B01D; B01D24/00; B01D24/46; B01D24/4631; B01D24/02; B01D24/10; B01D24/12
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2723761A
Cited
US2773829A
Cited
GB932537A
Cited
US3436260A
Cited
US3276585A
Cited
US3550774A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |