Patent US3390724A successfully refreshed from Google Patents.
US3390724A
Expired / Lapsed
US
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Duct forming device with a filter
Assignee: Zanal Corporation of Alberta Ltd
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Filing: 1966-02-01
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Granted: 1968-07-02
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Expires: 1986-02-01
Abstract
No abstract record available.
Inventors
- 👤 Caldwell Lyle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:54
CPC Classifications
E; E21; E21B; E21B43/00; E21B43/11; E21B34/00; E21B34/06; E21B34/063; E21B43/02; E21B43/08; E21B43/086
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1570725A
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US956080A
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US1811235A
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US2042537A
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US2004071A
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US2540123A
Cited
US2903069A
Cited
US2981333A
Cited
US3326291A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1971-07-02 | 1972-01-01 | 1972-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1975-07-02 | 1976-01-01 | 1976-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1979-07-02 | 1980-01-01 | 1980-07-02 | $7700.00 | Window Closed / Lapsed |