US2996973A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for an adjustable ventilation in tunnels or similar spaces
Assignee: Svenska Flaktfabriken AB
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Filing: 1959-02-20
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Granted: 1961-08-22
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Expires: 1979-02-20
Abstract
No abstract record available.
Inventors
- 👤 Boysen Arne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:56
CPC Classifications
E; E21; E21F; E21F1/00; E21F1/003
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-08-21 | 1965-02-20 | 1965-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-08-21 | 1969-02-20 | 1969-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-08-21 | 1973-02-20 | 1973-08-22 | $7700.00 | Window Closed / Lapsed |