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US2661769A
Expired / Lapsed
US
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Insulated air duct
Assignee: Achenbach & Butler Inc
•
Filing: 1950-04-08
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Granted: 1953-12-08
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Expires: 1970-04-08
Abstract
No abstract record available.
Inventors
- 👤 Leon E Butler
- 👤 Fredrick J Siemers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:17
CPC Classifications
F; F16; F16L; F16L59/00; F16L59/12
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2271929A
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US1611907A
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US1998422A
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US2009619A
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US1998423A
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US2148496A
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US2293351A
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US2370379A
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US2476499A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-12-07 | 1957-06-08 | 1957-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-12-07 | 1961-06-08 | 1961-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-12-07 | 1965-06-08 | 1965-12-08 | $7700.00 | Window Closed / Lapsed |