Patent US2500305A successfully refreshed from Google Patents.
US2500305A
Expired / Lapsed
US
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Electric oil well heater
Assignee: THERMACTOR Corp
•
Filing: 1946-05-28
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Granted: 1950-03-14
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Expires: 1966-05-28
Abstract
No abstract record available.
Inventors
- 👤 Charles S Ackley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:23
CPC Classifications
E; E21; E21B; E21B36/00; E21B36/04
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US495936A
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US573142A
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US1309721A
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US1426407A
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US806039A
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US1174570A
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US1232736A
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US1504208A
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US2134610A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-03-13 | 1953-09-12 | 1954-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-03-13 | 1957-09-12 | 1958-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-03-13 | 1961-09-12 | 1962-03-14 | $7700.00 | Window Closed / Lapsed |