Patent US3451554A successfully refreshed from Google Patents.
US3451554A
Expired / Lapsed
US
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Swimming pool filter with alternate flow valve control
Assignee: Hydrotech Chemical Corp
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Filing: 1968-09-10
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Granted: 1969-06-24
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Expires: 1988-09-10
Abstract
No abstract record available.
Inventors
- 👤 Charles E Wade
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:01
CPC Classifications
B; B01; B01D; B01D24/00; B01D24/02; B01D24/10; B01D24/14; B01D24/38; B01D24/40; B01D24/46; B01D24/4631; B01D24/4642
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-06-23 | 1972-12-23 | 1973-06-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-06-23 | 1976-12-23 | 1977-06-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-06-23 | 1980-12-23 | 1981-06-24 | $7700.00 | Window Closed / Lapsed |