Patent US2531139A successfully refreshed from Google Patents.
US2531139A
Expired / Lapsed
US
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Heater with safety screen air inlet
Assignee: Individual
•
Filing: 1948-05-07
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Granted: 1950-11-21
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Expires: 1968-05-07
Abstract
No abstract record available.
Inventors
- 👤 Russell M Lilly
- 👤 Bruno R Schabarum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:14
CPC Classifications
E; E21; E21B; E21B36/00; E21B36/02; E21B36/025
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) | 1953-11-20 | 1954-05-22 | 1954-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-11-20 | 1958-05-22 | 1958-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-11-20 | 1962-05-22 | 1962-11-21 | $7700.00 | Window Closed / Lapsed |