US1521578A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter for purifying the air
Assignee: Individual
•
Filing: 1924-03-15
•
Granted: 1924-12-30
•
Expires: 1944-03-15
Abstract
No abstract record available.
Inventors
- 👤 Wittemeier Hans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:07
CPC Classifications
B; B01; B01D; B01D45/00; B01D45/04; B01D45/08; Y; Y10; Y10S; Y10S261/00; Y10S261/72; Y10S55/00; Y10S55/24
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) | 1927-12-30 | 1928-06-30 | 1928-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1931-12-30 | 1932-06-30 | 1932-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1935-12-30 | 1936-06-30 | 1936-12-30 | $7700.00 | Window Closed / Lapsed |