US2939378A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Withdrawable duct ventilating system
Assignee: LIBBY ENGINEERING Ltd
•
Filing: 1957-07-15
•
Granted: 1960-06-07
•
Expires: 1977-07-15
Abstract
No abstract record available.
Inventors
- 👤 Zalkind Louis Allen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:16
CPC Classifications
F; F24; F24F; F24F7/00; F24F7/04; F24F7/06; F24F7/065; B; B08; B08B; B08B15/00; B08B15/02; F24F13/00; F24F13/02; F24F13/0218; F24F13/0236
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US358674A
Cited
US722288A
Cited
US806648A
Cited
US1064796A
Cited
GB288798A
Cited
US2575841A
Cited
US2693749A
Cited
GB758350A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-06-07 | 1963-12-07 | 1964-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-06-07 | 1967-12-07 | 1968-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-06-07 | 1971-12-07 | 1972-06-07 | $7700.00 | Window Closed / Lapsed |