Patent US3028816A successfully refreshed from Google Patents.
US3028816A
Expired / Lapsed
US
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Airlift pumps with valving baffles
Assignee: Walker Process Equipment Inc
•
Filing: 1958-04-22
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Granted: 1962-04-10
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Expires: 1978-04-22
Abstract
No abstract record available.
Inventors
- 👤 Walker James Donald
- 👤 Alfred W Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:29
CPC Classifications
F; F04; F04F; F04F1/00; F04F1/18
Claims Analysis
Total Claims: 0
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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) | 1965-04-09 | 1965-10-09 | 1966-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1969-04-09 | 1969-10-09 | 1970-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1973-04-09 | 1973-10-09 | 1974-04-10 | $7700.00 | Window Closed / Lapsed |