US4332772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Portable gas detector
Assignee: Industrial Scientific Corp
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Filing: 1981-06-12
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Granted: 1982-06-01
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Expires: 2001-06-12
Abstract
Abstract An improvement is provided in a portable gas detector used to detect combustible gases, such as methane, which embodies a Wheatstone bridge circuit including a refractory-coated detector element having thereon a catalyst for promoting oxidation of the combustible gas to be detected constituting one leg of the bridge and a refractory-coated reference element constituting a second leg of the bridge. The improvement consists in the application of a cobalt oxide coating to the reference element, whereby the occurrence of spurious signals by the Wheatstone bridge circuit due to causes other than the presence of a combustible gas is greatly reduced, if not completely eliminated.
Inventors
- 👤 Frank X. McNally
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:30
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/02; C23C18/12; C23C18/1204; C23C18/1208; C23C18/1216; G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/14; G01N27/16; Y; Y10; Y10T; Y10T436/00; Y10T436/21; Y10T436/218
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
149 words
In an apparatus for detecting a combustible gas which comprises a Wheatstone bridge circuit having (a) a detector element comprising an electrically conducting member coated with a refractory and having on the surface of said refractory a catalyst for the oxidation of said gas, said detector element constituting one leg of said bridge, and (b) a reference element comprising an electrically conducting member coated with a refractory, said reference element constituting a second leg of said bridge, whereby upon catalytic oxidation of said gas an electrical signal approximately proportional to the amount of said gas present at the detector element is produced, the improvement which comprises a coating of cobalt oxide deposited upon the refractory coating of said reference element, whereby the occurrence of spurious signals by the Wheatstone bridge circuit due to causes other than the presence of a combustible gas is greatly reduced, if not completely eliminated.
Claim 2
Dependent Claim
149 words
In an apparatus for detecting a combustible gas which comprises a Wheatstone bridge circuit having (a) a detector element comprising an electrically conducting member coated with a refractory and having on the surface of said refractory a catalyst for the oxidation of said gas, said detector element constituting one leg of said bridge, and (b) a reference element comprising an electrically conducting member coated with a refractory, said reference element constituting a second leg of said bridge, whereby upon catalytic oxidation of said gas an electrical signal approximately proportional to the amount of said gas present at the detector element is produced, the improvement which comprises a coating of cobalt oxide deposited upon the refractory coating of said reference element, whereby the occurrence of spurious signals by the Wheatstone bridge circuit due to causes other than the presence of a combustible gas is greatly reduced, if not completely eliminated.
Claim 3
Dependent Claim
145 words
In an apparatus for detecting methane which comprises a Wheatstone bridge circuit having (a) a detector element comprising a platinum coil coated with alumina and having on the surface of said alumina a catalyst selected from the class consisting of platinum, palladium, or mixtures thereof, said detector element constituting one leg of said bridge, and (b) a reference element comprising a platinum coil coated with alumina, said reference element constituting a second leg of said bridge, whereby upon catalytic oxidation of said methane an electrical signal approximately proportional to the amount of methane present at the detector element is produced, the improvement which comprises a coating of cobalt oxide deposited upon the alumina coating of said reference element, whereby the occurrence of spurious signals by the Wheatstone bridge circuit due to causes other than the presence of methane is greatly reduced, if not completely eliminated.
Claim 4
Dependent Claim
145 words
In an apparatus for detecting methane which comprises a Wheatstone bridge circuit having (a) a detector element comprising a platinum coil coated with alumina and having on the surface of said alumina a catalyst selected from the class consisting of platinum, palladium, or mixtures thereof, said detector element constituting one leg of said bridge, and (b) a reference element comprising a platinum coil coated with alumina, said reference element constituting a second leg of said bridge, whereby upon catalytic oxidation of said methane an electrical signal approximately proportional to the amount of methane present at the detector element is produced, the improvement which comprises a coating of cobalt oxide deposited upon the alumina coating of said reference element, whereby the occurrence of spurious signals by the Wheatstone bridge circuit due to causes other than the presence of methane is greatly reduced, if not completely eliminated.
References Cited (Backward Citations)
US2904765A
Cited
US2930016A
Cited
US3077774A
Cited
US3890703A
Cited
US4123225A
Cited
US4045177A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-31 | 1985-11-30 | 1986-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-31 | 1989-11-30 | 1990-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-31 | 1993-11-30 | 1994-06-01 | $7700.00 | Window Closed / Lapsed |