Patent US1446448A successfully refreshed from Google Patents.
US1446448A
Expired / Lapsed
US
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Continuously-operating air-pressure filter
Assignee: Individual
•
Filing: 1921-06-06
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Granted: 1923-02-27
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Expires: 1941-06-06
Abstract
No abstract record available.
Inventors
- 👤 John W Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:55
CPC Classifications
B; B01; B01D; B01D33/00; B01D33/80; B01D33/804; B01D33/807; B01D33/15; B01D33/21; B01D33/23; B01D33/44; B01D33/46; B01D33/463; B01D33/466; B01D33/70; B01D33/76; B01D33/766; B01D33/801; B01D35/00; B01D35/16
Claims Analysis
Total Claims: 0
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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) | 1926-02-26 | 1926-08-28 | 1927-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1930-02-26 | 1930-08-28 | 1931-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1934-02-26 | 1934-08-28 | 1935-02-27 | $7700.00 | Window Closed / Lapsed |