US3702397A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Infra-red gas detectors
Assignee: National Research Development Corp UK
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Filing: 1971-02-16
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Granted: 1972-11-07
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Expires: 1991-02-16
Abstract
Abstract Means for detecting a component of an atmosphere comprises a source of radiation and a detector arranged so as to receive and be responsive to radiation through said atmosphere from the source, the intensity of the radiation from the source increasing rapidly with respect to wavelength just below the peak of an absorption band of the chosen component, and the response of the detector decreasing rapidly with respect to wavelength just above the peak of the absorption band. Selection of source, detector and radiation filters allows detection of one component, such as methane or carbon monoxide, without falsification of the result by another component such as carbon dioxide.
Inventors
- 👤 Jack Graham Firth
- 👤 Thomas Alwyn Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:15
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/02; G01J3/10; G01J3/108
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
111 words
Apparatus for measuring the concentration of a constituent of an atmosphere, said constituent having an absorption band in the electromagnetic radiation spectrum, which comprises an enclosure into which the atmosphere under test can pass, a source of electromagnetic radiation the intensity of which increases rapidly with respect to increasing wavelength just below the peak of the said absorption band, a detecting system having a response to radiation which decreases rapidly with respect to increasing wavelength just above the peak of the said absorption band, said detecting system including a detector for detecting radiation which has passed from the source through the enclosure, and means for indicating the output of the detector.
Claim 2
Dependent Claim
111 words
Apparatus for measuring the concentration of a constituent of an atmosphere, said constituent having an absorption band in the electromagnetic radiation spectrum, which comprises an enclosure into which the atmosphere under test can pass, a source of electromagnetic radiation the intensity of which increases rapidly with respect to increasing wavelength just below the peak of the said absorption band, a detecting system having a response to radiation which decreases rapidly with respect to increasing wavelength just above the peak of the said absorption band, said detecting system including a detector for detecting radiation which has passed from the source through the enclosure, and means for indicating the output of the detector.
Claim 3
Dependent Claim
35 words
Apparatus according to claim 1 suitable for the detection of a hydrocarbon in which the source of electromagnetic radiation includes a heatable body of glass and the detecting system comprises an indium arsenide photovoltaic cell.
Claim 4
Dependent Claim
50 words
Apparatus according to claim 2 in which the body of glass is arranged as a coating on a ceramic bead heated internally by a platinum wire through which an electric current may be passed so as to heat the glass coating to a temperature in the range 500* to 700*C.
Claim 5
Dependent Claim
40 words
Apparatus according to claim 3 in which the side of the glass coated ceramic bead remote from the detector is coated with platinum so that when said bead is heated, radiation is reflected from the platinum coating towards the detector.
Claim 6
Dependent Claim
89 words
Apparatus according to claim 1 and having in the radiation path between the source of electromagnetic radiation and the detector, radiation absorption means which can absorb radiation at the absorption wavelength of a possible impurity in the atmosphere said impurity having an absorption wavelength close to or within the band of wavelengths between the wavelength at which the intensity of radiation emitted by the source increases rapidly with respect to increasing wavelength and the wavelength at which the response of the detector decreases rapidly with respect to increasing wavelength.
Claim 7
Dependent Claim
51 words
Apparatus according to claim 5 suitable for the detection of a hydrocarbon in which the source of electromagnetic radiation includes a heatable body of glass, the detecting system comprises an indium arsenide photovoltaic cell and having in the radiation path between said source and the detector at least one silica window.
Claim 8
Dependent Claim
39 words
Apparatus according to claim 5 in which the said radiation absorption means comprises a second enclosure containing a sufficient quantity of the possible impurity to absorb substantially all of the incident radiation at the absorption wavelength of the impurity.
Claim 9
Dependent Claim
59 words
Apparatus according to claim 7, suitable for the detection of carbon monoxide gas, in which the source of electromagnetic radiation includes a heatable body of silica and the detector comprises an indium antimonide photoconductive cell, and having in the radiation path between said source and detector at least one calcium difluoride window and a second enclosure containing carbon dioxide.
Claim 10
Dependent Claim
59 words
Apparatus according to claim 7, suitable for the detection of carbon dioxide gas in which the source of electromagnetic radiation includes a heatable body of silica and tHe detector comprises an indium antimonide photoconductive cell, and having in the radiation path between said source and detector at least one calcium difluoride window and a second enclosure containing carbon monoxide.
Claim 11
Dependent Claim
48 words
Apparatus according to claim 8 in which the heatable body comprises an outer silica tube, an inner silica element having a cylindrical outer surface a platinum wire would round the inner silica element, and an alumina filling, occupying the space between the inner element and the outer tube.
Claim 12
Dependent Claim
48 words
Apparatus according to claim 9 in which the heatable body comprises an outer silica tube, an inner silica element having a cylindrical outer surface a platinum wire would round the inner silica element and an alumina filling occupying the space between the inner element and the outer tube.
Claim 13
Dependent Claim
63 words
Apparatus according to claim 7, suitable for the detection of carbon monoxide gas, in which the source of electromagnetic radiation includes a heatable body of silica and the detector comprises a thermocouple, and having in the radiation path between said source and detector at least one calcium difluoride window, a second enclosure containing carbon dioxide and nearest to the detector a sapphire window.
Claim 14
Dependent Claim
63 words
Apparatus according to claim 7, suitable for the detection of carbon dioxide gas, in which the source of electromagnetic radiation includes a heatable body of silica and the detector comprises a thermocouple, and having in the radiation path between said source and detector at least one calcium difluoride window, a second enclosure containing carbon monoxide, and nearest to the detector a sapphire window.
Claim 15
Dependent Claim
27 words
Apparatus according to claim 1 in which the wall of the enclosure comprises a porous part through which the atmosphere under test can pass into said enclosure.
Claim 16
Dependent Claim
27 words
Apparatus according to claim 1 in which the inner wall of the enclosure is reflective to electromagnetic radiation at least of the wavelengths emitted by the source.
References Cited (Backward Citations)
GB694777A
Cited
US2806144A
Cited
US3005097A
Cited
US3227873A
Cited
US3462596A
Cited
US3536919A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-07 | 1976-05-08 | 1976-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-07 | 1980-05-08 | 1980-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-07 | 1984-05-08 | 1984-11-07 | $7700.00 | Window Closed / Lapsed |