Patent US2741897A successfully refreshed from Google Patents.
US2741897A
Expired / Lapsed
US
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Equalizing duct for hardening rooms
Assignee: Armstrong World Industries Inc
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Filing: 1950-11-03
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Granted: 1956-04-17
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Expires: 1970-11-03
Abstract
No abstract record available.
Inventors
- 👤 Riggins Alfred Patrick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:47
CPC Classifications
F; F25; F25D; F25D17/00; F25D17/04; F25D17/042; F25D17/047
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) | 1959-04-17 | 1959-10-17 | 1960-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1963-04-17 | 1963-10-17 | 1964-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1967-04-17 | 1967-10-17 | 1968-04-17 | $7700.00 | Window Closed / Lapsed |