US2443781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for determining the wall building properties of well drilling fluids
Assignee: Individual
•
Filing: 1943-01-23
•
Granted: 1948-06-22
•
Expires: 1963-01-23
Abstract
No abstract record available.
Inventors
- 👤 Vernon B Zacher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:48
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/06; E21B21/063; E21B21/065
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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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) | 1951-06-22 | 1951-12-22 | 1952-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1955-06-22 | 1955-12-22 | 1956-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1959-06-22 | 1959-12-22 | 1960-06-22 | $7700.00 | Window Closed / Lapsed |