US2748873A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Back pressure valve apparatus for automatically filling well conduit strings
Assignee: Baker Hughes Oilfield Operations LLC
•
Filing: 1953-04-27
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Granted: 1956-06-05
•
Expires: 1973-04-27
Abstract
No abstract record available.
Inventors
- 👤 John R Baker
- 👤 John F Muse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:55
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/10; Y; Y10; Y10T; Y10T137/00; Y10T137/1624; Y10T137/1632; Y10T137/1669; Y10T137/1677
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) | 1959-06-05 | 1959-12-05 | 1960-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1963-06-05 | 1963-12-05 | 1964-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1967-06-05 | 1967-12-05 | 1968-06-05 | $7700.00 | Window Closed / Lapsed |