Patent US1783181A successfully refreshed from Google Patents.
US1783181A
Expired / Lapsed
US
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Automatic resistance-controlled air and gas filter
Assignee: American Air Filter Co Inc
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Filing: 1927-12-23
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Granted: 1930-12-02
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Expires: 1947-12-23
Abstract
No abstract record available.
Inventors
- 👤 Hans E Birkholz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:44
CPC Classifications
B; B01; B01D; B01D46/00; B01D46/18; B01D46/24; B01D46/26; Y; Y10; Y10S; Y10S55/00; Y10S55/34
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) | 1933-12-01 | 1934-06-02 | 1934-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1937-12-01 | 1938-06-02 | 1938-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1941-12-01 | 1942-06-02 | 1942-12-02 | $7700.00 | Window Closed / Lapsed |