Patent US2809811A successfully refreshed from Google Patents.
US2809811A
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US
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Air preheater with heating and tempering means
Assignee: Individual
•
Filing: 1951-05-11
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Granted: 1957-10-15
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Expires: 1971-05-11
Abstract
No abstract record available.
Inventors
- 👤 Blomquist Uno Olof
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:27
CPC Classifications
F; F28; F28D; F28D19/00; F28D19/04; F28D19/041; F23; F23M; F23M20/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1558445A
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US1574547A
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US1649696A
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US2115338A
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US2181053A
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US2363870A
Cited
US2320911A
Cited
US2362940A
Cited
GB587035A
Cited
US2499358A
Cited
US2607564A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1960-10-14 | 1961-04-15 | 1961-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-10-14 | 1965-04-15 | 1965-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-10-14 | 1969-04-15 | 1969-10-15 | $7700.00 | Window Closed / Lapsed |