US3493472A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and apparatus for the purification of formaldehyde by rectification with plural stage condenser-absorber zones
Assignee: FISCHER APPARATE ROHR
•
Filing: 1966-11-28
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Granted: 1970-02-03
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Expires: 1986-11-28
Abstract
No abstract record available.
Inventors
- 👤 Rolf Schumacher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:02
CPC Classifications
C; C07; C07C; C07C45/00; C07C45/78; C07C45/81; C07C45/82
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US3296309A
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US2070864A
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US2241110A
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FR851182A
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FR887471A
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FR53112E
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US2527655A
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US2676143A
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US2790755A
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US3113972A
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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) | 1973-02-02 | 1973-08-04 | 1974-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-02-02 | 1977-08-04 | 1978-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-02-02 | 1981-08-04 | 1982-02-03 | $7700.00 | Window Closed / Lapsed |