Patent US2457818A successfully refreshed from Google Patents.
US2457818A
Expired / Lapsed
US
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Downward forced flow air heater for rooms
Assignee: Individual
•
Filing: 1944-12-07
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Granted: 1949-01-04
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Expires: 1964-12-07
Abstract
No abstract record available.
Inventors
- 👤 Sidney J Helman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:00
CPC Classifications
F; F24; F24H; F24H3/00; F24H3/02; F24H3/06; F24H3/065
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2047121A
Cited
USRE22482E
Cited
US1982139A
Cited
US1943596A
Cited
US2017621A
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US2318476A
Cited
US2382800A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1952-01-04 | 1952-07-05 | 1953-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-01-04 | 1956-07-05 | 1957-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-01-04 | 1960-07-05 | 1961-01-04 | $7700.00 | Window Closed / Lapsed |