Patent US3520111A successfully refreshed from Google Patents.
US3520111A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gas filter apparatus
Assignee: American Air Filter Co Inc
•
Filing: 1968-11-05
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Granted: 1970-07-14
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Expires: 1988-11-05
Abstract
No abstract record available.
Inventors
- 👤 Alan E Revell
- 👤 Wilson A Welch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:34
CPC Classifications
B; B03; B03C; B03C3/00; B03C3/34; B03C3/86
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2380992A
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US2486521A
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US2555125A
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US2662608A
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US2780305A
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US3028715A
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US3173774A
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US3237383A
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US3271932A
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US3438180A
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US3392509A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-07-13 | 1974-01-12 | 1974-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-07-13 | 1978-01-12 | 1978-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-07-13 | 1982-01-12 | 1982-07-14 | $7700.00 | Window Closed / Lapsed |