Patent US2697421A successfully refreshed from Google Patents.
US2697421A
Expired / Lapsed
US
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Control for waste heat boilers
Assignee: Combustion Engineering Inc
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Filing: 1952-08-02
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Granted: 1954-12-21
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Expires: 1972-08-02
Abstract
No abstract record available.
Inventors
- 👤 Robert M Nalven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:45
CPC Classifications
F; F02; F02G; F02G5/00; F02G5/02; F22; F22B; F22B1/00; F22B1/02; F22B1/18; F22B1/1807; Y; Y02; Y02E; Y02E20/00; Y02E20/30; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
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) | 1957-12-20 | 1958-06-21 | 1958-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-12-20 | 1962-06-21 | 1962-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-12-20 | 1966-06-21 | 1966-12-21 | $7700.00 | Window Closed / Lapsed |