US2673718A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotary air preheater with cooling means
Assignee: Individual
•
Filing: 1949-09-28
•
Granted: 1954-03-30
•
Expires: 1969-09-28
Abstract
No abstract record available.
Inventors
- 👤 Ljungstrom Fredrik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:51
CPC Classifications
F; F28; F28D; F28D19/00; F28D19/04; F28D19/041; Y; Y10; Y10S; Y10S165/00; Y10S165/009; Y10S165/013; Y10S165/016; Y10S165/027; Y10S165/921
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
GB257974A
Cited
DE533780C
Cited
US1762320A
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US2125721A
Cited
US2313081A
Cited
US2392325A
Cited
US2347857A
Cited
US2418815A
Cited
US2413645A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-03-29 | 1957-09-28 | 1958-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-03-29 | 1961-09-28 | 1962-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-03-29 | 1965-09-28 | 1966-03-30 | $7700.00 | Window Closed / Lapsed |