Patent US2638581A successfully refreshed from Google Patents.
US2638581A
Expired / Lapsed
US
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Signal device for filters
Assignee: Briggs Filtration Co
•
Filing: 1950-06-21
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Granted: 1953-05-12
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Expires: 1970-06-21
Abstract
No abstract record available.
Inventors
- 👤 Harvey E Marvel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:43
CPC Classifications
B; B01; B01D; B01D35/00; B01D35/14; B01D35/143; Y; Y10; Y10S; Y10S116/00; Y10S116/42
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1411802A
Cited
DE471732C
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US1685211A
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US2145304A
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US2294330A
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US2328131A
Cited
US2348651A
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US2458086A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-05-11 | 1956-11-10 | 1957-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-05-11 | 1960-11-10 | 1961-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-05-11 | 1964-11-10 | 1965-05-12 | $7700.00 | Window Closed / Lapsed |