Patent US4000400A successfully refreshed from Google Patents.
US2583930A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gas analyzer and smoke detector
Assignee: Factory Mutual Research Corp
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Filing: 1948-12-04
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Granted: 1952-01-29
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Expires: 1968-12-04
Abstract
No abstract record available.
Inventors
- 👤 Paul E Cotton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:46
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/14; G01N27/16
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
70 words
A GAS DETECTOR COMPRISING TWO RESISTANCE ELEMENTS, EACH INCLUDING A CATALYTICALLY ACTIVE CONDUCTOR HAVING MARKED CHANGE IN ELECTRICAL RESISTANCE IN RESPONSE TO CHANGE IN TEMPERATURE, THE TWO CONDUCTORS BEING SUBSTANTITALLY IDENTICAL IN MATERIAL, CROSS-SECTIONAL AREA AND LENGTH, AND THE SURFACES OF THE TWO CONDUCTORS BEING EXPOSED TO THE GAS SUBSTANTIALLY IN THE SAME WAY AND TO THE SAME EXTENT, AN INDICATOR, AND ELECTRICAL CIRCUIT CONNECTING SAID CONDUCTORS TO A SOURCE
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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) | 1955-01-28 | 1955-07-30 | 1956-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1959-01-28 | 1959-07-30 | 1960-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1963-01-28 | 1963-07-30 | 1964-01-29 | $7700.00 | Window Closed / Lapsed |