Patent US3487837A successfully refreshed from Google Patents.
US2113577A
Expired / Lapsed
US
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Direct top strata-of-liquid heater
Assignee: Individual
•
Filing: 1936-07-20
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Granted: 1938-04-12
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Expires: 1956-07-20
Abstract
No abstract record available.
Inventors
- 👤 Theodore F Dittmar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:46
CPC Classifications
F; F24; F24H; F24H1/00; F24H1/10; F24H1/12; F24H1/127
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1941-04-11 | 1941-10-11 | 1942-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1945-04-11 | 1945-10-11 | 1946-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1949-04-11 | 1949-10-11 | 1950-04-12 | $7700.00 | Window Closed / Lapsed |