US2431772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Downflow forced draft air heater
Assignee: Individual
•
Filing: 1944-12-22
•
Granted: 1947-12-02
•
Expires: 1964-12-22
Abstract
No abstract record available.
Inventors
- 👤 Kephart P Russell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:06
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)
US526475A
Cited
US2047121A
Cited
US1175069A
Cited
US1583238A
Cited
US1757898A
Cited
GB304446A
Cited
FR726200A
Cited
US2166834A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1950-12-01 | 1951-06-02 | 1951-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1954-12-01 | 1955-06-02 | 1955-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1958-12-01 | 1959-06-02 | 1959-12-02 | $7700.00 | Window Closed / Lapsed |