US3560735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flow responsive detector for infrared gas analyzers
Assignee: MSA Safety Inc
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Filing: 1968-10-09
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Granted: 1971-02-02
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Expires: 1988-10-09
Abstract
Abstract A flow responsive detector for use in an infrared gas analyzer includes a pair of gas chambers, at least one of which is adapted to be irradiated by a pulsed beam of infrared energy to produce alternate heating and cooling, and concomitant expansion and contraction, of the gas therein when that gas contains a radiation absorbing component. A sensor responsive to gas flow in the form of a thermistor that has a negative temperature coefficient of resistance and a rate of change of resistance that varies inversely with temperature is mounted in a flow chamber, which is connected by a separate passage with each gas chamber. Where these passages enter the flow chamber, they are provided with jet orifices for directing a high velocity stream or jet flow of gas on the sensor in response to the expansion and contraction of gas in at least one of the gas chambers, thereby greatly enhancing the favorable nonlinear response characteristics of the sensor.
Inventors
- 👤 John P Strange
- 👤 Ray S Freilino
- 👤 Earl M Becker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:37
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/33; G01N21/3103; G01N21/35; G01N21/3504; G01N21/3518; G01N21/37
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
272 words
A flow-responsive detector unit for use in an infrared gas anaLyzer of the type in which the gas component of interest is selectively detected and measured by its absorption of a pulsed beam of infrared energy, said detector unit comprising: a pair of gas chambers at least one of which is adapted to be irradiated by a pulsed beam of infrared energy and to contain a gas absorbing such energy in the same spectral region as the component of interest, a gas flow chamber, and electrically heated resistance sensor responsive to gas flow and having a rate of change of resistance that increases as its temperature decreases mounted in the flow chamber, a separate passage connecting each gas chamber to the flow chamber, each passage terminating at the flow chamber in an orifice member having a jet orifice to provide relatively high velocity jet flow across the surface of the sensor to enhance the cooling effect of such gas flow by the entrainment of cool gas in the flow chamber as gas flows from one gas chamber to the other in response to the alternate expansion and contraction of the gas in at least one of the gas chamber when subjected to said pulsed infrared energy, the jet orifices being substantially axially aligned with each other with the sensor mounted substantially midway between the orifices and adjacent their axes, means for initially adjusting each orifice member in a separate defined plane normal to the axes of the orifices for initially locating the orifices in axial alignment with the sensor and with each other, and means for maintaining the orifices in such alignment.
Claim 2
Dependent Claim
272 words
A flow-responsive detector unit for use in an infrared gas anaLyzer of the type in which the gas component of interest is selectively detected and measured by its absorption of a pulsed beam of infrared energy, said detector unit comprising: a pair of gas chambers at least one of which is adapted to be irradiated by a pulsed beam of infrared energy and to contain a gas absorbing such energy in the same spectral region as the component of interest, a gas flow chamber, and electrically heated resistance sensor responsive to gas flow and having a rate of change of resistance that increases as its temperature decreases mounted in the flow chamber, a separate passage connecting each gas chamber to the flow chamber, each passage terminating at the flow chamber in an orifice member having a jet orifice to provide relatively high velocity jet flow across the surface of the sensor to enhance the cooling effect of such gas flow by the entrainment of cool gas in the flow chamber as gas flows from one gas chamber to the other in response to the alternate expansion and contraction of the gas in at least one of the gas chamber when subjected to said pulsed infrared energy, the jet orifices being substantially axially aligned with each other with the sensor mounted substantially midway between the orifices and adjacent their axes, means for initially adjusting each orifice member in a separate defined plane normal to the axes of the orifices for initially locating the orifices in axial alignment with the sensor and with each other, and means for maintaining the orifices in such alignment.
Claim 3
Dependent Claim
107 words
Apparatus according to claim 1, in which the sensor is a thermistor bead supported in a well in a block, the block being provided with opposed openings in its wall for loosely receiving the orifice members and being provided with counterbores in the outer ends of those openings remote from the well terminating in flat bottom faces parallel to each other, and in which the means for initially adjusting each orifice member includes a flange on each of said members of smaller diameter than the counterbore and having a bearing surface normal to the axis of the orifice for slidably engaging the bottom face of the counterbore.
Claim 4
Dependent Claim
80 words
Apparatus according to claim 2, in which said means for maintaining the orifices in alignment include a deformable insert disposed in each counterbore and of substantially the same diameter as the counterbore, each insert overlying the flange of an orifice member and adapted to deform under clamping pressure to flow between the edge of the flange and the wall of the counterbore to lock the orifice member in a given position, and means for subjecting the inserts to clamping pressure.
Claim 5
Dependent Claim
35 words
Apparatus according to claim 1, in which the sensor is a thermistor bead that has a substantially ellipsoidal shape, and in which the axes of the bead and the axes of the orifices are coincident.
Claim 6
Dependent Claim
23 words
Apparatus according to claim 1, that also includes means for cooling the gas in said passages before such gas enters the flow chamber.
Claim 7
Dependent Claim
27 words
Apparatus according to claim 5, in which the cooling means include thermoelectric elements in said passages, and means for thermally insulating those passages adjacent the thermoelectric elements.
References Cited (Backward Citations)
US2555327A
Cited
GB786516A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |