US2197770A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter bed cleaning
Assignee: Individual
•
Filing: 1938-11-02
•
Granted: 1940-04-23
•
Expires: 1958-11-02
Abstract
No abstract record available.
Inventors
- 👤 Francis L Pruyn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:12
CPC Classifications
B; B01; B01D; B01D24/00; B01D24/002; B01D24/02; B01D24/20; B01D24/22; B01D24/28; B01D24/38; B01D24/44; B01D24/46; B01D24/4668; B01D24/4689
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) | 1943-04-23 | 1943-10-23 | 1944-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-04-23 | 1947-10-23 | 1948-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-04-23 | 1951-10-23 | 1952-04-23 | $7700.00 | Window Closed / Lapsed |