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Patent US2217143A successfully refreshed from Google Patents.
US2217143A
Expired / Lapsed
US
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Purification of petroleum contaminated waters
Assignee: Dow Chemical Co
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Filing: 1937-09-21
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Granted: 1940-10-08
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Expires: 1957-09-21
Abstract
No abstract record available.
Inventors
- 👤 Ralph A Stevenson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:14
CPC Classifications
B; B01; B01D; B01D17/00; B01D17/02; B01D17/0205; B01D17/0208; B01D17/04; B01D17/047
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1943-10-08 | 1944-04-08 | 1944-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-10-08 | 1948-04-08 | 1948-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-10-08 | 1952-04-08 | 1952-10-08 | $7700.00 | Window Closed / Lapsed |