US3439477A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for gas filtration
Assignee: National Research Development Corp UK
•
Filing: 1968-04-26
•
Granted: 1969-04-22
•
Expires: 1988-04-26
Abstract
No abstract record available.
Inventors
- 👤 Humphrey Walter Pyne
- 👤 Bruce Horwood
- 👤 Robin Burnell Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:23
CPC Classifications
B; B01; B01D; B01D46/00; B01D46/10
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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AT193854B
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US2970671A
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US2961064A
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US3190057A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-04-21 | 1972-10-21 | 1973-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-04-21 | 1976-10-21 | 1977-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-04-21 | 1980-10-21 | 1981-04-22 | $7700.00 | Window Closed / Lapsed |