Patent US3533611A successfully refreshed from Google Patents.
US3533611A
Expired / Lapsed
US
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Furnace ventilation system
Assignee: Wheelabrator Corp
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Filing: 1968-06-06
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Granted: 1970-10-13
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Expires: 1988-06-06
Abstract
No abstract record available.
Inventors
- 👤 James F Boyer
- 👤 Alfred E Kroll
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:43
CPC Classifications
F; F27; F27D; F27D17/00; F27D17/30; F27D17/304
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-10-12 | 1974-04-13 | 1974-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-10-12 | 1978-04-13 | 1978-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-10-12 | 1982-04-13 | 1982-10-13 | $7700.00 | Window Closed / Lapsed |