CA1071709A - Gas analysis apparatus - Google Patents
Gas analysis apparatusInfo
- Publication number
- CA1071709A CA1071709A CA264,567A CA264567A CA1071709A CA 1071709 A CA1071709 A CA 1071709A CA 264567 A CA264567 A CA 264567A CA 1071709 A CA1071709 A CA 1071709A
- Authority
- CA
- Canada
- Prior art keywords
- gas
- diffusion
- aperture
- electrochemical cell
- electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/4065—Circuit arrangements specially adapted therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
- G01N27/4072—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure characterized by the diffusion barrier
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Molecular Biology (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrochemical cell is used in combination with a gas diffusion limiting orifice or aperture in order to measure the limiting flow of electrochemically active gaseous species through the aperture, thus rendering the electrical signal developed by the electrochemical cell an indication of the partial pressure of the gas species to which the electrochemical cell is responsive.
An electrochemical cell is used in combination with a gas diffusion limiting orifice or aperture in order to measure the limiting flow of electrochemically active gaseous species through the aperture, thus rendering the electrical signal developed by the electrochemical cell an indication of the partial pressure of the gas species to which the electrochemical cell is responsive.
Description
BACKGROUND OF THE_INVENTION
While numerous techniques and devices have been developed for monitoring the partial pressure of gas con-stituents using both solid and liquid electrolytes9 the practical usefulness of some embodiments of these devices, especially those operating in a current mode, is often limited due to sensitivity to variations in gas flow rate and temperature, as well as degradation of electrode structure.
A typical illustration of an electrochemical cell operating in a diffusion limited current mode of operation is described and illustrated in U.S. Patent 3,691,023, entitled "Method for Polarographic Measurement of Oxygen Partial Pressure", issued September 12, 1972 assigned to the assignee of the present invention. In this invention, an oxygen ion conductive solid electrolyte electrochemical cell monitors the oxygen partial pressure of a gas. A potential is applied across the electrodes of the electrochemical cell of sufficient magnitude to deplete the oxygen present at an electrode/electrolyte interface such that the current measured is a h~
i :
.. , : .
46,213 1~7~709 function of the oxygen diffusing through the pores of the electrode thus establishing the electrochemical cell in a diffusion limited current mode of operatlonO A linear rela-tionship exists between the diffusion current and the partial pressure of the gas constituent of interest herein chosen to be oxygen, and thus the diffusion current can be represented as a direct indication of the oxygen partial pressure of the sample gas. A device constructed in accordance with thls invention is generally limited to monitoring relatively low gas partial pressures lnasmuch as the presence of a high partial pressure sample gas would require an unduly large electrical potential to be applied across the electrodes deplete the oxygen at the electrode/electrolyte interface to achieve the diffusion llmited current mode of operation.
Further, the operation of a device in accordance with this invention would be sensitive to variations in gas flow rate and changes in the structure of the electrodes which alter the diffusion characteristics of the electrodesO
SUMMARY OF THE INVENTION
There is disclosed herein with reference to the accompanying drawings a technique for improving the practical usefulness of electrochemical cells which measure currents llmited by gas diffusion. There is disclosed herein an assembly including an adapter having an ~nternal chamber and a electrochemical cell forming part of one wall such that an internal electrode of the cell is exposed to the environment in the internal chamber and an external electrode is exposed to a different environment and a gas diffusion aperture, separate and apart from the electrochemical cell that is 3o sized to support the diffusion of gas species from an ` 46,213 envlronment external to the adapter into the internal chamber.
: An electrical potential is applied across the electrodes of the electrochemical cell to pump the gas species of interest from the internal chamber thereby establishing a pressure gradient across the aperture for the gas species of interest and developing a current flcw which is directly proportional to the amount of the gas species dif~using through the apertureO The magnitude of the potential applied across the electrodes of the electrochemical cell need only be suf~l-cient to maintain a partial pressure gradient across the gas diffusion aperture to assure gas diffusion to the internal electrode.
In accordance with the technique disclosed hereln, the gas diffusion aperture in the housing or adapter coupled to the electrochemical cell is the factor determinlng the gas diffusion characteristic in contrast with the above-identified prior art devices wherein the electrode size and pore structure determines the gas diffusion capability of the gas measuring deviceO
Furthermore, inasmuch as the electrode structure is no longer the critical factor in determining gas diffuslon, changes in electrode porosity or structure over the oper-ating life of the electrochemical cell will not significantly affect the operation of the improved electrochemical cell device disclosed hereinO
Finally, variations in flow rate of the gas within the monitored gas environment will not significantly affect the operation of the improved electrochemical cell device inasmuch as variations in flow rate are not transmitted through the gas diffusion aperture.
46,213 1C~7~709 BRIEF DESCRIPTION OF THE DRAWINGS
_ The invention will become more readily apparent from the following exemplary description ln connection with the accompanying drawings:
Figure 1 is a section schematic illustration of an -~embodiment of the invention;
Figures 2 and 3 are graph~cal lllustrations of the operation of the invention typically illustrated ln Figure l; and Figure 4 is a schematic illustration of an alternate embodiment of the invention shown in Figure lo DESCRIPTION OF THE PRE~ERRED EMBODIMENT
The invention disclosed herein has direct applica-tion to any and all gas monitoring electrochemical cells regardless of the cell composltionO While the embodiment selected and illustrated in Figure 1 for the purposes of describing the invention is that of a solid electrolyte electrochemical cell, it will be apparent that the disclosed inventive technique applies likewise to liquld and polymeric electrolytes incorporated in devices for monitoring gas constituents of interest, i.eO oxygen, sodium, chlorine, hydrogen, etc. The invention relates not to the electro-chemical cell per se, but rather to the use of an adapter or housing having a gas diffusion aperture therein which llmlts the exposure of an electrode of an electrochemical cell to a sample of the monitored gas environment which passes through the gas diffusion aperture.
Referring to Figure 1, there is schematically lllustrated a gas monitoring assembly 10 including an elec-trochemical cell 20 of the type described and illustrated ln 46,213 ~)7~709 the above-identified U.SO patent and consistlng of solid electrolyte 24, lnternal electrode 22 and external electrode 26 sealed within a wall of a gas diffusion adapter 30. The gas dlffusion adapter 30 includes a gas diffusion aperture 32 of a size to limit the gas from the monitored gas envlron-ment G entering the chamber 34 and contacting internal electrode 22 to the gas specles that diffuse through the aperture 320 The electrolyte material is selected on the basis of the electrochemically active gas species which is to be monitored. If oxygen ls of interest, an electrolyte material is selected which supports the transfer of oxygen~
if sodium is the gas species of interest then a sodium conductive electrolyte material is selected, etc.
The structure of internal electrode 22 is porous so as to readily transfer the gas species of interest.
Platinum represents a conventional electrode composition.
As noted above, the electrolyte material composltion is selected to support conduction of the gas species of lnterest.
In particular, the embodiment selected for illustrating the invention consists of an oxygen ion conductlve solid electro-lyte which exhibits significant oxygen ion conductlvity and minimum electronic conductivity and corresponds in structure and composition to any one of numerous solid electrolyte oxygen cells. As indicated above, the selection of electro-chemical cell materials is dependent upon the gas species of interest. For instance in an appliction for monitoring sodium ions9 the electrochemical cell 20 of Flgure 1 would be replaced by an electrochemical cell having an electrolyte exhibiting significant sodium ion conductivity, i.e. such as beta-aluminaO Similarly the electrochemical cell composition . 46,213 1~7~709 can be varied to lnclude numerous polymer, solld or liquid electrolyte suitable for monitoring a gas species o~ lnterest.
In the embodiment illustrated in Figure 1, external electrode 26 can be exposed to the monitored gas envlronment G or other environments including air. Notably, there ls no requirement for a stable reference gas environment in contact with electrode 260 The diffusion of gas from the monitored gas environ-ment G through the gas diffusion aperture 32 into the internal chamber 34 is established by the application of a DC potential from source 40 across the electrodes 22 and 26 of a polarity as indicated to pump oxygen, the gas specles of lnterest, i.eO oxygen, present in the internal chamber 34 through the electrolyte 24 to the electrode 26 so as to establlsh a pressure gradient across the aperture 32. This causes diffusion of oxygen from the monitored gas envlronment G through the gas diffusion aperture 32 into the chamber 34.
The size of the internal electrode 22 is sufficiently large in area with respect to the size of the gas diffusion aper-ture 32 that the gas diffusion through the gas dlffusionaperture 32 never equals ~r exceeds the gas diffusion capa-city of the lnternal electrode 22. In other words, it ls the size of the gas diffusion aperture 32, and not the size of the internal electrode 22, which is the gas diffusion limiting factor in the gas measurlng combination 10. In this arrangement, it is the diffusion of gas through the gas diffusion aperture 32 that determines the transfer of charge through the electrolyte 24 and the resulting current monitored by the current measuring circuit 42. This contrast with the diffusion limited mode of operation described in the above 46,213 ~71'70g .~
referenced U.S. patent whereln the capacity of internal electrode 22 for gas transfer determines the transfer of charge through the electrolyte and thus determines the measured cell currentO
Yet another ma~or distinction between the operatlon of the prior art devices and the concept illustrated in Figures 1 and 4 is the criticality of the DC potential applied across the electrodes of the electrochemical cell.
As noted above, the applled potential of the prior art devices required to establish a diffusion limited current mode of operation must be sufficiently large so as to deplete the oxygen present at the electrode/electrolyte interface and must be sufficiently stable to maintain this condition.
Inasmuch as the prior art devices are exposed to what corre-sponds to the monitored gas environment G, the operation of the cell is dependent on the capability of the applied potential to deplete the gas constituent of interest from the sensing electrode/electrolyte interface. The operatlon of such a device is limited to relatlvely low partial pres-sures inasmuch as conventional electrochemical cell structuresare incapable of tolerating the level of potential that w~uld be required to establish the diffusion limited current mode of operation of a cell directly exposed to a gas con-taining relatively high partial pressures of the gas constit-uent of interestO
In the embodiment of Figure lg it is not the internal electrode 22 which establishes the di~fusion limlted current mode of operation but rather the si~e of the gas diffusion aperture 320 It is apparent therefore that the magnitude of the DC potential developed by source l~o is ~ 46,213 -1C~71709 selected solely for the purposes of maintaining a partial pressure gradient across the gas diffusion aperture 32 to assure diffusion o~ gas from the monitored gas envlronment G
into the internal chamber 34.
The fact that the size of the gas dlffusion aper- -ture 32 determines the diffusion limiting characteristic of the gas monitoring combination 10, frees the selection of design of electrochemical cell 20 and the selection of the magnitude of the applied potential to render the operation of electrochemical cell 20 substantially free of temperature changes.
Referring to Figure 2 there is graphlcally lllus-trated several plots of measured cell current versus percent oxygen at predetermined operating temperatures, applied potentials and gas diffusion aperture diameters. The knee in the curves 5, 6, 7 and 8 represents the transition in the mode of operation of the cell from a diffusion mode established by the gas diffusion aperture 32 represented by the linear portion of the curves while the portion of curves occurring after the knee correspond to the condition whereln the current is limited by the diffuslon characteristics of the electrode as disclosed in the above-referenced U.S. patent.
It is noted, that the linear portion of curves 3 and 5, which correspond to the same gas mixture, applied potential, and-gas aperture~ but at different ambient temperatures coincide exactly thus indicating the relative insensitivity of the gas monitoring combination lO to variations in temperature.
A typical plot of gas aperture size versus cell sensitivity is illustrated in Figure 3. While it is under-4~,213 ~071709 stood that the selection of a nominal size opening for the gas diffusion aperture 32 will assure a wide range of gas partial pressure response for the combination 10, optimizatlon of the selection of the size of the gas diffusion aperture 32 can be realized through the use of a curve of the type illustrated in Figure 3.
Whlle the electrode 26 of the em~odiment of Flgure 1 ls e~posed to the monitored gas environment G, thus clearly indicating the lack of a need for a stable gas reference environment, the embodiment of the combinatlon 10 ln the flange F of Figure 4 isolates the electrode 26 from the monitored gas environment G flowing in plpe P while exposing the electrode 22 to the gas from the monitored gas envlronment G diffusing through aperture 32.
While the most practical implementativn of this invention employs a gas adapter having a single gas dlffusion aperture~ it is apparent that variations incorporating more than one gas diffusion aperture can be employed as the operational requirements dictate.
While numerous techniques and devices have been developed for monitoring the partial pressure of gas con-stituents using both solid and liquid electrolytes9 the practical usefulness of some embodiments of these devices, especially those operating in a current mode, is often limited due to sensitivity to variations in gas flow rate and temperature, as well as degradation of electrode structure.
A typical illustration of an electrochemical cell operating in a diffusion limited current mode of operation is described and illustrated in U.S. Patent 3,691,023, entitled "Method for Polarographic Measurement of Oxygen Partial Pressure", issued September 12, 1972 assigned to the assignee of the present invention. In this invention, an oxygen ion conductive solid electrolyte electrochemical cell monitors the oxygen partial pressure of a gas. A potential is applied across the electrodes of the electrochemical cell of sufficient magnitude to deplete the oxygen present at an electrode/electrolyte interface such that the current measured is a h~
i :
.. , : .
46,213 1~7~709 function of the oxygen diffusing through the pores of the electrode thus establishing the electrochemical cell in a diffusion limited current mode of operatlonO A linear rela-tionship exists between the diffusion current and the partial pressure of the gas constituent of interest herein chosen to be oxygen, and thus the diffusion current can be represented as a direct indication of the oxygen partial pressure of the sample gas. A device constructed in accordance with thls invention is generally limited to monitoring relatively low gas partial pressures lnasmuch as the presence of a high partial pressure sample gas would require an unduly large electrical potential to be applied across the electrodes deplete the oxygen at the electrode/electrolyte interface to achieve the diffusion llmited current mode of operation.
Further, the operation of a device in accordance with this invention would be sensitive to variations in gas flow rate and changes in the structure of the electrodes which alter the diffusion characteristics of the electrodesO
SUMMARY OF THE INVENTION
There is disclosed herein with reference to the accompanying drawings a technique for improving the practical usefulness of electrochemical cells which measure currents llmited by gas diffusion. There is disclosed herein an assembly including an adapter having an ~nternal chamber and a electrochemical cell forming part of one wall such that an internal electrode of the cell is exposed to the environment in the internal chamber and an external electrode is exposed to a different environment and a gas diffusion aperture, separate and apart from the electrochemical cell that is 3o sized to support the diffusion of gas species from an ` 46,213 envlronment external to the adapter into the internal chamber.
: An electrical potential is applied across the electrodes of the electrochemical cell to pump the gas species of interest from the internal chamber thereby establishing a pressure gradient across the aperture for the gas species of interest and developing a current flcw which is directly proportional to the amount of the gas species dif~using through the apertureO The magnitude of the potential applied across the electrodes of the electrochemical cell need only be suf~l-cient to maintain a partial pressure gradient across the gas diffusion aperture to assure gas diffusion to the internal electrode.
In accordance with the technique disclosed hereln, the gas diffusion aperture in the housing or adapter coupled to the electrochemical cell is the factor determinlng the gas diffusion characteristic in contrast with the above-identified prior art devices wherein the electrode size and pore structure determines the gas diffusion capability of the gas measuring deviceO
Furthermore, inasmuch as the electrode structure is no longer the critical factor in determining gas diffuslon, changes in electrode porosity or structure over the oper-ating life of the electrochemical cell will not significantly affect the operation of the improved electrochemical cell device disclosed hereinO
Finally, variations in flow rate of the gas within the monitored gas environment will not significantly affect the operation of the improved electrochemical cell device inasmuch as variations in flow rate are not transmitted through the gas diffusion aperture.
46,213 1C~7~709 BRIEF DESCRIPTION OF THE DRAWINGS
_ The invention will become more readily apparent from the following exemplary description ln connection with the accompanying drawings:
Figure 1 is a section schematic illustration of an -~embodiment of the invention;
Figures 2 and 3 are graph~cal lllustrations of the operation of the invention typically illustrated ln Figure l; and Figure 4 is a schematic illustration of an alternate embodiment of the invention shown in Figure lo DESCRIPTION OF THE PRE~ERRED EMBODIMENT
The invention disclosed herein has direct applica-tion to any and all gas monitoring electrochemical cells regardless of the cell composltionO While the embodiment selected and illustrated in Figure 1 for the purposes of describing the invention is that of a solid electrolyte electrochemical cell, it will be apparent that the disclosed inventive technique applies likewise to liquld and polymeric electrolytes incorporated in devices for monitoring gas constituents of interest, i.eO oxygen, sodium, chlorine, hydrogen, etc. The invention relates not to the electro-chemical cell per se, but rather to the use of an adapter or housing having a gas diffusion aperture therein which llmlts the exposure of an electrode of an electrochemical cell to a sample of the monitored gas environment which passes through the gas diffusion aperture.
Referring to Figure 1, there is schematically lllustrated a gas monitoring assembly 10 including an elec-trochemical cell 20 of the type described and illustrated ln 46,213 ~)7~709 the above-identified U.SO patent and consistlng of solid electrolyte 24, lnternal electrode 22 and external electrode 26 sealed within a wall of a gas diffusion adapter 30. The gas dlffusion adapter 30 includes a gas diffusion aperture 32 of a size to limit the gas from the monitored gas envlron-ment G entering the chamber 34 and contacting internal electrode 22 to the gas specles that diffuse through the aperture 320 The electrolyte material is selected on the basis of the electrochemically active gas species which is to be monitored. If oxygen ls of interest, an electrolyte material is selected which supports the transfer of oxygen~
if sodium is the gas species of interest then a sodium conductive electrolyte material is selected, etc.
The structure of internal electrode 22 is porous so as to readily transfer the gas species of interest.
Platinum represents a conventional electrode composition.
As noted above, the electrolyte material composltion is selected to support conduction of the gas species of lnterest.
In particular, the embodiment selected for illustrating the invention consists of an oxygen ion conductlve solid electro-lyte which exhibits significant oxygen ion conductlvity and minimum electronic conductivity and corresponds in structure and composition to any one of numerous solid electrolyte oxygen cells. As indicated above, the selection of electro-chemical cell materials is dependent upon the gas species of interest. For instance in an appliction for monitoring sodium ions9 the electrochemical cell 20 of Flgure 1 would be replaced by an electrochemical cell having an electrolyte exhibiting significant sodium ion conductivity, i.e. such as beta-aluminaO Similarly the electrochemical cell composition . 46,213 1~7~709 can be varied to lnclude numerous polymer, solld or liquid electrolyte suitable for monitoring a gas species o~ lnterest.
In the embodiment illustrated in Figure 1, external electrode 26 can be exposed to the monitored gas envlronment G or other environments including air. Notably, there ls no requirement for a stable reference gas environment in contact with electrode 260 The diffusion of gas from the monitored gas environ-ment G through the gas diffusion aperture 32 into the internal chamber 34 is established by the application of a DC potential from source 40 across the electrodes 22 and 26 of a polarity as indicated to pump oxygen, the gas specles of lnterest, i.eO oxygen, present in the internal chamber 34 through the electrolyte 24 to the electrode 26 so as to establlsh a pressure gradient across the aperture 32. This causes diffusion of oxygen from the monitored gas envlronment G through the gas diffusion aperture 32 into the chamber 34.
The size of the internal electrode 22 is sufficiently large in area with respect to the size of the gas diffusion aper-ture 32 that the gas diffusion through the gas dlffusionaperture 32 never equals ~r exceeds the gas diffusion capa-city of the lnternal electrode 22. In other words, it ls the size of the gas diffusion aperture 32, and not the size of the internal electrode 22, which is the gas diffusion limiting factor in the gas measurlng combination 10. In this arrangement, it is the diffusion of gas through the gas diffusion aperture 32 that determines the transfer of charge through the electrolyte 24 and the resulting current monitored by the current measuring circuit 42. This contrast with the diffusion limited mode of operation described in the above 46,213 ~71'70g .~
referenced U.S. patent whereln the capacity of internal electrode 22 for gas transfer determines the transfer of charge through the electrolyte and thus determines the measured cell currentO
Yet another ma~or distinction between the operatlon of the prior art devices and the concept illustrated in Figures 1 and 4 is the criticality of the DC potential applied across the electrodes of the electrochemical cell.
As noted above, the applled potential of the prior art devices required to establish a diffusion limited current mode of operation must be sufficiently large so as to deplete the oxygen present at the electrode/electrolyte interface and must be sufficiently stable to maintain this condition.
Inasmuch as the prior art devices are exposed to what corre-sponds to the monitored gas environment G, the operation of the cell is dependent on the capability of the applied potential to deplete the gas constituent of interest from the sensing electrode/electrolyte interface. The operatlon of such a device is limited to relatlvely low partial pres-sures inasmuch as conventional electrochemical cell structuresare incapable of tolerating the level of potential that w~uld be required to establish the diffusion limited current mode of operation of a cell directly exposed to a gas con-taining relatively high partial pressures of the gas constit-uent of interestO
In the embodiment of Figure lg it is not the internal electrode 22 which establishes the di~fusion limlted current mode of operation but rather the si~e of the gas diffusion aperture 320 It is apparent therefore that the magnitude of the DC potential developed by source l~o is ~ 46,213 -1C~71709 selected solely for the purposes of maintaining a partial pressure gradient across the gas diffusion aperture 32 to assure diffusion o~ gas from the monitored gas envlronment G
into the internal chamber 34.
The fact that the size of the gas dlffusion aper- -ture 32 determines the diffusion limiting characteristic of the gas monitoring combination 10, frees the selection of design of electrochemical cell 20 and the selection of the magnitude of the applied potential to render the operation of electrochemical cell 20 substantially free of temperature changes.
Referring to Figure 2 there is graphlcally lllus-trated several plots of measured cell current versus percent oxygen at predetermined operating temperatures, applied potentials and gas diffusion aperture diameters. The knee in the curves 5, 6, 7 and 8 represents the transition in the mode of operation of the cell from a diffusion mode established by the gas diffusion aperture 32 represented by the linear portion of the curves while the portion of curves occurring after the knee correspond to the condition whereln the current is limited by the diffuslon characteristics of the electrode as disclosed in the above-referenced U.S. patent.
It is noted, that the linear portion of curves 3 and 5, which correspond to the same gas mixture, applied potential, and-gas aperture~ but at different ambient temperatures coincide exactly thus indicating the relative insensitivity of the gas monitoring combination lO to variations in temperature.
A typical plot of gas aperture size versus cell sensitivity is illustrated in Figure 3. While it is under-4~,213 ~071709 stood that the selection of a nominal size opening for the gas diffusion aperture 32 will assure a wide range of gas partial pressure response for the combination 10, optimizatlon of the selection of the size of the gas diffusion aperture 32 can be realized through the use of a curve of the type illustrated in Figure 3.
Whlle the electrode 26 of the em~odiment of Flgure 1 ls e~posed to the monitored gas environment G, thus clearly indicating the lack of a need for a stable gas reference environment, the embodiment of the combinatlon 10 ln the flange F of Figure 4 isolates the electrode 26 from the monitored gas environment G flowing in plpe P while exposing the electrode 22 to the gas from the monitored gas envlronment G diffusing through aperture 32.
While the most practical implementativn of this invention employs a gas adapter having a single gas dlffusion aperture~ it is apparent that variations incorporating more than one gas diffusion aperture can be employed as the operational requirements dictate.
Claims (2)
1. Apparatus for determining the partial pressure of a predetermined gas constituent in a monitored gas environ-ment, comprising the combination of:
a housing having a gas diffusion aperture therethrough to support the diffusion of a predetermined gas constituent from a gas environment external to said housing into said housing, a solid electrolyte electrochemical cell having first and second electrodes disposed on opposite surfaces thereof and said solid electrolyte being a composition to support ion con-ductivity of said predetermined gas constituent of interest, said first electrode being exposed to the gas constituent dif-fusing through said aperture, voltage means connected across said first and second electrodes, said voltage means being of a polarity to establish said solid electrolyte electrochemical cell in a pumping mode of operation, the magnitude of the voltage being such as to maintain a partial pressure gradient across said gas diffusion aperture to assure diffusion of said gas constituent from said monitored gas environment into said housing, the area of said first electrode being sufficiently large with respect to the size of said gas diffusion aperture that the diffusion of said gas constituent through said gas diffusion aperture is less than the gas diffusion capacity of said first electrode, the size of said gas diffusion aperture establishing the diffusion limiting characteristic of the combination, and current measuring means operatively connected to said solid electrolyte electrochemical cell to measure the current flow established by said solid electrolyte electrochemical cell, said current being a function of the rate of diffusion of the gas constituent of interest through said gas diffusion aperture, said current being indicative of the partial pressure of said gas constituent in said monitored gas environment.
a housing having a gas diffusion aperture therethrough to support the diffusion of a predetermined gas constituent from a gas environment external to said housing into said housing, a solid electrolyte electrochemical cell having first and second electrodes disposed on opposite surfaces thereof and said solid electrolyte being a composition to support ion con-ductivity of said predetermined gas constituent of interest, said first electrode being exposed to the gas constituent dif-fusing through said aperture, voltage means connected across said first and second electrodes, said voltage means being of a polarity to establish said solid electrolyte electrochemical cell in a pumping mode of operation, the magnitude of the voltage being such as to maintain a partial pressure gradient across said gas diffusion aperture to assure diffusion of said gas constituent from said monitored gas environment into said housing, the area of said first electrode being sufficiently large with respect to the size of said gas diffusion aperture that the diffusion of said gas constituent through said gas diffusion aperture is less than the gas diffusion capacity of said first electrode, the size of said gas diffusion aperture establishing the diffusion limiting characteristic of the combination, and current measuring means operatively connected to said solid electrolyte electrochemical cell to measure the current flow established by said solid electrolyte electrochemical cell, said current being a function of the rate of diffusion of the gas constituent of interest through said gas diffusion aperture, said current being indicative of the partial pressure of said gas constituent in said monitored gas environment.
2. Apparatus as claimed in claim 1 wherein said gas constituent of interest is oxygen, said solid electro-lyte electrochemical cell exhibiting oxygen ion conductivity.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63799875A | 1975-12-05 | 1975-12-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1071709A true CA1071709A (en) | 1980-02-12 |
Family
ID=24558227
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA264,567A Expired CA1071709A (en) | 1975-12-05 | 1976-11-01 | Gas analysis apparatus |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5926895B2 (en) |
| AU (1) | AU502736B2 (en) |
| BE (1) | BE849063A (en) |
| CA (1) | CA1071709A (en) |
| DE (1) | DE2654483A1 (en) |
| FR (1) | FR2334101A1 (en) |
| GB (1) | GB1523550A (en) |
| IT (1) | IT1064510B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4776943A (en) * | 1984-02-20 | 1988-10-11 | Nissan Motor Co., Ltd. | Device for detecting air-fuel ratio of mixture over wide range from below to above stoichiometric ratio |
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| US4158166A (en) * | 1976-11-24 | 1979-06-12 | Westinghouse Electric Corp. | Combustibles analyzer |
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| US4231733A (en) * | 1978-05-31 | 1980-11-04 | Westinghouse Electric Corp. | Combined O2 /combustibles solid electrolyte gas monitoring device |
| JPS559178A (en) * | 1978-07-07 | 1980-01-23 | Nippon Denso Co Ltd | Oxygen concentration detector |
| DE2911548A1 (en) * | 1979-03-23 | 1980-09-25 | Bayer Ag | GAS DETECTOR |
| DE2923483A1 (en) * | 1979-06-09 | 1980-12-11 | Bosch Gmbh Robert | POLAROGRAPHIC PROBE FOR DETERMINING THE OXYGEN CONTENT IN GAS, ESPECIALLY IN EXHAUST GAS FROM COMBUSTION ENGINES |
| NL7906833A (en) * | 1979-09-13 | 1981-03-17 | Philips Nv | GAS ANALYZER. |
| FR2466016A1 (en) * | 1979-09-21 | 1981-03-27 | Thomson Csf | Exhaust gas analyser for IC engine - has metallic cap protecting measuring cell screwed into exhaust assembly |
| US4449919A (en) * | 1980-07-10 | 1984-05-22 | Tokyo Shibaura Denki Kabushiki Kaisha | Gas combustion apparatus capable of detecting environmental oxygen deficiency |
| JPS57154049A (en) * | 1981-03-19 | 1982-09-22 | Toyota Motor Corp | Oxygen sensor element |
| JPS57154050A (en) * | 1981-03-19 | 1982-09-22 | Toyota Motor Corp | Oxygen sensor element |
| JPS58182151U (en) * | 1982-05-31 | 1983-12-05 | 株式会社フジクラ | solid electrolyte oxygen meter |
| JPS5931444A (en) * | 1982-08-16 | 1984-02-20 | Hitachi Ltd | Lean sensor |
| JPS5958356A (en) * | 1982-09-28 | 1984-04-04 | Fuji Electric Corp Res & Dev Ltd | Gas analysis apparatus and its production |
| US4659435A (en) * | 1983-02-18 | 1987-04-21 | Corning Glass Works | Integrally heated electrochemical cell method and apparatus |
| JPS59163556A (en) * | 1983-03-08 | 1984-09-14 | Nippon Denso Co Ltd | Oxygen concentration detecting apparatus |
| JPS59184854A (en) * | 1983-04-06 | 1984-10-20 | Hitachi Ltd | Oxygen sensor |
| JPH065220B2 (en) * | 1983-07-04 | 1994-01-19 | トヨタ自動車株式会社 | Oxygen concentration detector |
| JPS6017452U (en) * | 1983-07-14 | 1985-02-06 | トヨタ自動車株式会社 | oxygen concentration detector |
| JPS6025958U (en) * | 1983-07-28 | 1985-02-21 | 株式会社フジクラ | Oxygen concentration measuring device |
| JPS5985951A (en) * | 1983-10-03 | 1984-05-18 | Nissan Motor Co Ltd | Apparatus for measuring oxygen concentration |
| JPS6086457A (en) * | 1983-10-19 | 1985-05-16 | Hitachi Ltd | Air fuel ratio sensor for controlling engine |
| JPH0612354B2 (en) * | 1983-11-28 | 1994-02-16 | 株式会社日立製作所 | Method for manufacturing oxygen concentration measuring device |
| JPS6091251A (en) * | 1983-10-26 | 1985-05-22 | Hitachi Ltd | Air-fuel ratio sensor |
| JPS6093341A (en) * | 1983-10-27 | 1985-05-25 | Fujikura Ltd | Oxygen concentration sensor |
| JPS60114764A (en) * | 1983-11-28 | 1985-06-21 | Fujikura Ltd | Measurement of oxygen concentration |
| JPS59192953A (en) * | 1983-12-12 | 1984-11-01 | Toyota Central Res & Dev Lab Inc | Analytical apparatus for concentration of gaseous oxygen |
| JPS60235047A (en) * | 1984-05-07 | 1985-11-21 | Toyota Motor Corp | Method for controlling temperature of oxygen sensor with heater for internal-combustion engine |
| JPS60235048A (en) * | 1984-05-07 | 1985-11-21 | Toyota Motor Corp | Method for controlling supply of current to resistance heat generation type electric heater of oxygen sensor |
| JPS6118856A (en) * | 1984-07-06 | 1986-01-27 | Fujikura Ltd | Heating of sensor |
| US4568443A (en) * | 1984-09-06 | 1986-02-04 | Mitsubishi Denki Kabushiki Kaisha | Air-to-fuel ratio sensor |
| DE3433187C2 (en) * | 1984-09-10 | 1986-11-27 | Mitsubishi Denki K.K., Tokio/Tokyo | Sensor for measuring the air / fuel ratio |
| JPS61132854A (en) * | 1984-11-30 | 1986-06-20 | Shimadzu Corp | Limiting current type oxygen sensor |
| FR2575551B1 (en) * | 1984-12-27 | 1987-03-06 | Brunel Gerald | OXYGEN PROBE DEVICE AND ELECTRONIC COMBUSTION CONTROL EQUIPMENT PROVIDED WITH SUCH A PROBE |
| JPH0743340B2 (en) * | 1985-04-15 | 1995-05-15 | 三洋電機株式会社 | Oxygen concentration detector |
| GB2182447B (en) * | 1985-10-18 | 1990-01-24 | Honda Motor Co Ltd | Device for measuring a component of a gaseous mixture |
| US4762605A (en) * | 1986-02-01 | 1988-08-09 | Fuji Electric Co., Ltd. | Oxygen sensor |
| EP0281375A3 (en) * | 1987-03-04 | 1989-11-29 | Westinghouse Electric Corporation | Oxygen analyzer |
| JPH0291556A (en) * | 1988-09-29 | 1990-03-30 | Fujikura Ltd | Oxygen concentration analyzer |
| DE3908393A1 (en) * | 1989-03-15 | 1990-09-27 | Bosch Gmbh Robert | SENSOR ELEMENT FOR LIMIT CURRENT SENSORS FOR DETERMINING THE (LAMBDA) VALUE OF GAS MIXTURES |
| DE19721232A1 (en) * | 1996-05-31 | 1997-12-04 | Electrovac | Oxygen particle pressure sensor with two measuring ranges |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3400054A (en) * | 1966-03-15 | 1968-09-03 | Westinghouse Electric Corp | Electrochemical method for separating o2 from a gas; generating electricity; measuring o2 partial pressure; and fuel cell |
| US3514377A (en) * | 1967-11-27 | 1970-05-26 | Gen Electric | Measurement of oxygen-containing gas compositions and apparatus therefor |
| US3650934A (en) * | 1969-11-14 | 1972-03-21 | Westinghouse Electric Corp | Oxygen control and measuring apparatus |
| DE2317914A1 (en) * | 1973-04-10 | 1974-10-24 | Bbc Brown Boveri & Cie | METHOD OF MEASURING LOW OXYGEN CONTENT IN LIQUIDS AND SOLIDS |
| US3860498A (en) * | 1973-07-02 | 1975-01-14 | Westinghouse Electric Corp | Method of measuring O{HD 2 {B and O{HD 2 {B containing constituents |
| NL7309537A (en) * | 1973-07-09 | 1975-01-13 | Philips Nv | GAS ANALYSIS DEVICE. |
-
1976
- 1976-11-01 CA CA264,567A patent/CA1071709A/en not_active Expired
- 1976-12-01 DE DE19762654483 patent/DE2654483A1/en not_active Ceased
- 1976-12-02 AU AU20195/76A patent/AU502736B2/en not_active Expired
- 1976-12-02 GB GB5025676A patent/GB1523550A/en not_active Expired
- 1976-12-03 FR FR7636475A patent/FR2334101A1/en active Granted
- 1976-12-03 BE BE172970A patent/BE849063A/en not_active IP Right Cessation
- 1976-12-03 IT IT3008976A patent/IT1064510B/en active
- 1976-12-06 JP JP51145700A patent/JPS5926895B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4776943A (en) * | 1984-02-20 | 1988-10-11 | Nissan Motor Co., Ltd. | Device for detecting air-fuel ratio of mixture over wide range from below to above stoichiometric ratio |
Also Published As
| Publication number | Publication date |
|---|---|
| BE849063A (en) | 1977-06-03 |
| DE2654483A1 (en) | 1977-07-07 |
| IT1064510B (en) | 1985-02-18 |
| GB1523550A (en) | 1978-09-06 |
| AU2019576A (en) | 1978-06-08 |
| AU502736B2 (en) | 1979-08-09 |
| JPS5269690A (en) | 1977-06-09 |
| FR2334101B1 (en) | 1981-01-02 |
| FR2334101A1 (en) | 1977-07-01 |
| JPS5926895B2 (en) | 1984-07-02 |
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