US3864628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective solid-state gas sensors and method
Assignee: Gas Technology Institute
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Filing: 1973-05-29
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Granted: 1975-02-04
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Expires: 1993-05-29
Abstract
Abstract A method for detecting gases by selectively moving a gas through a gas permeable membrane to a semiconductor sensor which qualitatively reports such gas as an electrical output after a predetermined time lag. The time-output information is recognized as a result of previous calibration of the sensor and gas permeable membrane with known gases, such calibrations comprising standards for comparison. The method is practiced to advantage with a gas detection assembly including a housing which holds a gas permeable membrane in spaced relationship to the gas sensor which may operate at elevated temperatures from a heating element therein. The gas detection assembly is used in circuits having detection means which may be audio or visual, including meter readout.
Inventors
- 👤 Donald L Klass
- 👤 Carl D Landahl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:58
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0011; G01N33/0014; G01N33/0027; G01N33/0036; G01N33/005
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
72 words
A method for detecting a selected gas with a solid state gas sensor present in an electric circuit with output detection means, including the steps of exposing said gas sensor to gases, including the selected gas, only through a gas permeable membrane which is highly selective for permeating said selected gas, and determining the characteristic time response lag of said sensor to said selected gas by actuation of the circuit detection means.
Claim 2
Independent Claim
72 words
A method for detecting a selected gas with a solid state gas sensor present in an electric circuit with output detection means, including the steps of exposing said gas sensor to gases, including the selected gas, only through a gas permeable membrane which is highly selective for permeating said selected gas, and determining the characteristic time response lag of said sensor to said selected gas by actuation of the circuit detection means.
Claim 3
Dependent Claim
24 words
A method for detecting gases which includes the steps of claim 1 above wherein the gas sensor is a bulk N-type metal oxide sensor.
Claim 4
Dependent Claim
48 words
A method for detecting gases which includes the steps of claim 2 above wherein said method is practiced for detecting the presence of hydrogen, and said gas sensor is exposed to said hydrogen gas only through a polyester gas permeable membrane which is highly selective for permeating hydrogen.
Claim 5
Dependent Claim
45 words
A method for qualitatively detecting gases which includes the steps of claim 2 above wherein the method is practiced for detecting methane, and said gas sensor is exposed to said methane only through a polychloroprene permeable membrane which is highly selective for permeating said methane.
Claim 6
Dependent Claim
39 words
A method for qualitatively detecting a selected gas which includes the steps of claim 2 above, and which further includes the step of comparing said time response lag with standardized time-output information for that selected gas with said membrane.
Claim 7
Dependent Claim
64 words
A method for qualitatively detecting gases which includes the steps of claim 2 aBove in which the electric circuit further includes means for measuring current output, and which further includes the steps of awaiting current output to become substantially steady, recording the elapsed time to reach such steady current output, and comparing said time-output with standardized time-output information for known gases permeating said membrane.
Claim 8
Dependent Claim
134 words
A method for qualitatively detecting gases which includes the steps of claim 5 above and which further includes moving a mixture of at least two gases through a gas permeable membrane highly selective for one of said gases to expose a gas sensor thereto, at the same time, moving said gas mixture through a second gas permeable membrane highly selective to permeation of the other gas in the mixture to expose another gas sensor to that gas, compensating for the output which corresponds to the most readily permeated gas through one of said membranes, and noting the electrical output of the other of said gases which permeates more readily through the other of said gas permeable membranes, said output being then compared with standardized time-output information for known gases with said known other membrane.
Claim 9
Dependent Claim
93 words
An electronic gas detection means for detecting a selected gas including a solid-state gas sensor and a gas permeable membrane spaced from and covering an inlet to said gas sensor for providing a characteristic time lag as the selected gas permeates said membrane and activates said sensor, a voltage source connected to said gas sensor, conductors joined to said gas sensor, and detection means, being responsive following a characteristic time lag, to predetermined levels of electrical output from the gas sensor resulting from the lowering of its resistivity after exposure to a gas.
Claim 10
Dependent Claim
93 words
An electronic gas detection means for detecting a selected gas including a solid-state gas sensor and a gas permeable membrane spaced from and covering an inlet to said gas sensor for providing a characteristic time lag as the selected gas permeates said membrane and activates said sensor, a voltage source connected to said gas sensor, conductors joined to said gas sensor, and detection means, being responsive following a characteristic time lag, to predetermined levels of electrical output from the gas sensor resulting from the lowering of its resistivity after exposure to a gas.
Claim 11
Dependent Claim
55 words
An electronic gas detection means which includes the features of claim 8 above wherein said voltage source is a low level direct current voltage, and wherein said detection means include an indicating means and a unijunction transistor oscillator which frequency increases with electrical output of the gas sensor, said oscillator correspondingly actuating said indicating means.
Claim 12
Dependent Claim
51 words
An electronic gas detection means which includes the features of claim 9 above wherein the voltage source is an alternating current voltage, said electric gas detection means further including a step-down transformer and rectifier means for rectifying the output thereof so that said detection means may be actuated by direct current.
Claim 13
Dependent Claim
116 words
An electronic gas detection means which includes the features of claim 10 above which further includes a purging gas source for directing gas against the gas permeable membrane, electrical switching means normally open to allow such purged gas to move to the membrane, a first relay, means to enegize said first relay for a predetermined time period, said energized first relay closing the electrical switch means to stop the flow of purging gas to the gas membrane, a second relay energized by the changing electrical output of the gas sensor, and a third relay means actuating the detection means, and reset switch means for opening the energized circuit for the detection means to thereby deactivate it.
Claim 14
Dependent Claim
126 words
An electronic gas detection means which includes the features of claim 8 above wherein said voltage source is a low level direct current voltage, and which further includes a second solid-state gas sensor having a heating element, and a gas permeable membrane spaced from and covering an inlet to said second gas sensor, said gas permeable membrane associated with said gas sensor, amplifier means for amplifying the output from one of said gas sensors, logarithmic amplifier means for amplifying the output from the other said gas sensors, and variable resistor means for adjusting the logarithmic amplifier means to compensate for the output of one of the gas sensors which gas permeable membrane is more highly selective for a gas in a mixture contacting both gas sensors.
Claim 15
Dependent Claim
34 words
A Method for detecting gases which include the steps of claim 1 wherein said characteristic time response lag is determined by recording the time response to attain a recordable output level of said sensor.
Claim 16
Dependent Claim
34 words
A method for detecting gases which include the steps of claim 1 wherein said characteristic time response lag is determined by recording the time response to attain a steady output level of the sensor.
Claim 17
Dependent Claim
33 words
A method for detecting gases which includes the steps of claim 1 wherein said characteristic time response lag is determined by recording the output level of the sensor at a predetermined response time.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |