CA1240365A - Gas analyzer comprising gas pervious/liquid impervious membrane - Google Patents
Gas analyzer comprising gas pervious/liquid impervious membraneInfo
- Publication number
- CA1240365A CA1240365A CA000495539A CA495539A CA1240365A CA 1240365 A CA1240365 A CA 1240365A CA 000495539 A CA000495539 A CA 000495539A CA 495539 A CA495539 A CA 495539A CA 1240365 A CA1240365 A CA 1240365A
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- CA
- Canada
- Prior art keywords
- membrane
- gas
- cell
- cathode
- passage
- 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
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N7/00—Analysing materials by measuring the pressure or volume of a gas or vapour
-
- 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
- G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
-
- 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
- G01N27/416—Systems
- G01N27/49—Systems involving the determination of the current at a single specific value, or small range of values, of applied voltage for producing selective measurement of one or more particular ionic species
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Pathology (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
- Sampling And Sample Adjustment (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Secondary Cells (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Fuel Cell (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A gas analyzer cell includes an insulator body having a central passage divided into a first cell chamber and a second expansion chamber by a flexible expansion membrane. The cell chamber contains an anodic mass of a nonpolarizable metal and is enclosed by a uniformly curved cathodic member of polarizable metal which is covered by a membrane impervious to liquid but pervious to gas. An electrolyte fills the cell chamber.
The cathode and the gas permeable membrane are covered by a fibrous layer which is pervious to gas and is in turn covered by a metallic mesh held in place by a ring disc held securely to the insulator body. The metallic mesh and the fibrous layer hold the cathode membrane uniformly and tightly against the cathode of the cell so that the membrane does not lift or change its position under conditions of increased internal pressure and, consequently, incorrect results are eliminated.
A gas analyzer cell includes an insulator body having a central passage divided into a first cell chamber and a second expansion chamber by a flexible expansion membrane. The cell chamber contains an anodic mass of a nonpolarizable metal and is enclosed by a uniformly curved cathodic member of polarizable metal which is covered by a membrane impervious to liquid but pervious to gas. An electrolyte fills the cell chamber.
The cathode and the gas permeable membrane are covered by a fibrous layer which is pervious to gas and is in turn covered by a metallic mesh held in place by a ring disc held securely to the insulator body. The metallic mesh and the fibrous layer hold the cathode membrane uniformly and tightly against the cathode of the cell so that the membrane does not lift or change its position under conditions of increased internal pressure and, consequently, incorrect results are eliminated.
Description
1;~40~6S
GAS ANALYZER
Back round of the Invention g The present invention relates to gas analyzers and, more particularly, to an improved electrochemical gas analyzer.
Various types of electrolytic oxygen sensing devices are available for use in measuring the oxygen content of gaseous mixtures and the dissolved oxygen content of fluids. Typically, these devices utilize an electrolytic cell employing a pair of spaced electrodes immersed in an electrolyte. The cells utilize an electrical parameter derived from the reduction of oxygen to determine the concentration of oxygen.
In US. Patent No. 3,429,796, an electrochemical gas analyzer is disclosed in which linearity of response is improved by use of a flat, planar mesh cathode covered with a plastic membrane.
This provides a uniform electrolyte film between the cathode and the membrane necessary for accurate response over a large range.
U. S. Patent No. 3,767,552 discloses an electrochemical gas analyzer cell which utilizes an expansion membrane and chamber to eliminate the ~240~6S
lifting of the cathode membrane in the face of quick changes of the temperature or pressure due to the fact that the internal volume changes. on upwardly protruding, uniformly curved cathode provides intimate and continuous contact with a stretched, gas-permeable cathode membrane to provide a highly stable response.
It has been found that even such a device gives incorrect results when used in environments in which the content of the measured substance includes substantial amounts of nitrous oxide because the cell acts upon the nitrous oxide to form nitrogen gas which is less permeable through the plastic cathode ; membrane than is nitrous oxide and may thus cause a substantial rise in internal volume and internal pressure, after the expansion membrane reaches its expanded limit. Also, it has been found that highly permeable background gases such as hydrogen and helium can diffuse easily into the cell and produce excessive internal volume expansions and pressures which all result in the lifting of the cathode membrane.
Jo .
~3L291~D36S
Summary of the Invention Therefore, an object of this invention is to greatly lessen the sensitivity of an electrochemical gas analyzer cell to internal pressures caused by highly permeable background gas.
This and other objectives and advantages of the invention are accomplished by a gas analyzer cell which includes an insulator body having a central passage divided into a first cell chamber and a second expansion chamber by a flexible expansion membrane. The cell chamber contains an anodic mass of. a nonpolarizable metal and is enclosed by a uniformly curved cathodic member of polarizable metal which is covered by a membrane impervious to liquid but previous to gas. An electrolyte fills the cell chamber.
The slightly upwardly protruding curved cathode and the gas permeable membrane are covered by a fibrous layer which is previous to gas and is in turn covered by a metallic mesh held in place by a ring disc held securely to the insulator body. The metallic mesh and the fibrous layer hold the cathode membrane uniformly and tightly against the cathode of the cell so that the membrane does not lift or change ISLE I
its position under conditions of increased internal pressure and, consequently, incorrect results are eliminated.
Brief Description of the Drawings The invention will be better understood by reference to the detailed description considered in conjunction with drawings in which:
inure 1 is a sectional view of the gas analyzer in accordance with the invention; and Figure 2 is an exploded perspective view of the assembly forming the analyzer of the invention.
Description of the Preferred Embodiment Referring now to Figures 1 and 2, an analyzer cell 10 is shown housed in an insulator body 14. The body 14 of the cell 10 is formed of an insulating material which in the preferred embodiment may be a thermoplastic hydrocarbon resin such as polyethylene. Such a material facilitates the formation of heat seals with various portions of the device. The cell 10 is a sealed unit adapted to be utilized until the available anodic metal is converted to an oxidized form. The cell 10 is then discarded and replaced with a new cell.
~L2~0~65 The body 14 of the cell 10 is preferably cylindrical in shape and is adapted for insertion into a holder, not shown. An axial passage 16 extends through the body 14. The passage 16 is divided into an upper electrolyte cell chamber 18 and a lower expansion chamber 20 by means of a flexible, expansion membrane 22 attached to the body 14 at a shoulder 24 of the passage 16. The membrane 22 may be sealed to the body 14 by adhesive or by heat sealing techniques. Above the shoulder 24, the passage 16 forms a broad cylindrical aperture 27 and is constricted at a flange 26 to a smaller cylindrical aperture 28. An anode 30 has its upper surface held in place by the flange 26.
The expansion chamber 20 is enclosed by an end plate 32 attached at a shoulder 34 in the passage 16 of the body 14 by adhesive or heat sealing. The end plate 32 may be formed of a rigid insulating material such as glass reinforced epoxy. A bottom surface 38 of the plate 32 is provided with an anode contact area and a cathode contact area (neither of which is shown) by plating or applying contact foil as is well known to the prior art.
The anode 30 is formed of a porous, high surface area body of a non-polarizable metal such 124(~365 as lead, cadmium, or antimony which does not react with the electrolyte. In a preferred embodiment, the anode 30 contains a central aperture 46 for rapid transmission of pressure waves or surges to the expansion membrane 22.
The anode 30 is preferably formed of lead by sistering in situ. More particularly, the particulate lead is preferably formed into a cohesive mass and is preliminarily treated to remove any oxide coating on the surfaces of the particles. By way of illustration, lead granules having an average size between 5 and 10 miss are placed within thy boy 14 in a forming tool and are covered with a 10 percent solution of potassium hydroxide. While still covered by the potassium hydroxide, the lead is compressed to shape so that the particles stinter into a cohesive mass, and the oxide coating is removed.
A contact wire 52 is connected to the anode 30. The wire 52 is threaded through a small diameter aperture 54 into a machined bore 56 extending into the side of the body 14. The wire 52 is welded to a conductive plug 58, suitably formed of stainless steel received in the bore 56. A further length of wire 60 is welded to the exterior of the plug 58.
The wire 60 is reinserted into the body 14 through an ., -12~0~65 aperture 64 below the expansion membrane 22. The wire 52 is then threaded through an aperture 66 in the end plate 32 and is connected to the anode contact on the surface 38.
The top surface of the anode 30 may be enclosed by a disc 70 of a material permeable to liquid but impermeable to solids to prevent particles that break away from the anode 30 from moving within the electrolyte into contact with the cathode and partially shorting the cell 10. The disc 70 is suitably formed of filter paper and is retained in place by a plastic washer 72 which presses the edge of the disc 70 onto the central top surface of the anode 30.
The cell chamber 18 is enclosed by a convex, perforated cathode 74. The outer edge 76 of the cathode 74 is received in a shoulder 80 on the aperture 28 of the passage 16 through the body 14. A
gas-permeable, liquid-impermeable membrane 84 is stretched over the cathode 74 and has its outer edge heat sealed in a grove 86 provided in the upper surface of the flange 26. The grove 86 may be filled with a sealant.
A connecting wire 90 is welded to the cathode 74 and is threaded through a hole 92 into a 124~365 g second bore 94 provided in the side of the cell body 14. The wire 90 is welded to a conductive sealing plug 96 received in the bore 94. An additional wire 98 is welded to the outside surface of the plug 96 and extends down and into the body 14 through an aperture 102 in the body below the expansion membrane 22. The wire 98 continues through an aperture 104 in the base plate 32 into contact with the cathode contact on the surface 38.
Since smoothness and uniformity of the outer cathode surface provides more uniform and intimate contact with the cathode membrane, it is preferred to utilize a planar, multi-apertured metal material. The planar, multi-apertured metal material may be formed from electroformed or electroetched metals or from perforated metal sheet or metal film.
The cathode surface is formed of a polarizable metal, suitably a noble metal such as gold, silver or platinum. The cathode may be formed of an inner core which is plated or coated with the noble metal. The core is preferably a resistance weldable material so as to facilitate connection to the contact wires. By way of exemplification, the cathode can be formed from brass first plated with silver and then with gold.
124036~;
The malleable cathode 74 is formed into the desired convex shape with appropriately shaped forming tools. The curvature of the cathode is sufficient to tension the membrane to assure firm contact with the cathode but does not stretch the membrane beyond its elastic limit.
The cathode 74 is preferably capable of assuming and maintaining a convex shape such that the cathode does not bend, wrinkle or distort under conditions of usage. Suitably, the gold plated, brass cathode has a thickness of 10-25 miss to provide the desired inflexibility.
The cathode membrane 84 is stretched over the cathode 74 and sealed in place. The cathode membrane 84 seals the electrolyte within the cell 10 while permitting passage of gas into the cell 10.
The membrane 84 is preferably a synthetic organic resin inert to the electrolyte and is suitably a vinyl resin such as polyethylene, polypropylene or polytetrafluoroethylene.
In order to eliminate the lifting of the cathode membrane 84 caused by an excessive pressure within the cell 10, a fibrous element 110 is positioned over the cathode membrane 84 and a second mesh element 112 of the same size and shape as the cathode 74 and constructed of nickle-plated brass is positioned there over. The element 112 is held in place by a stainless steel ring 114 held in a cavity 116 in the body 14 by stainless steel screws 118.
The element 112 is cushioned by the fibrous element 110 so that it conforms to the surface thereof and lends substantial strength to eliminate lifting of the cathode membrane 84 which might be caused by pressure in the cell 10. The fibrous element 110 is constructed of a material which is porous and therefore permeable to the gas subject to measurement. In a preferred embodiment, a porous Teflon material having a thickness of 0.010 inches and openings of approximately one to two microns is utilized.
The expansion membrane 22 is formed of a flexible synthetic resin and is provided in a thickness and of a material such that it is more flexible than the cathode membrane 84. The expansion membrane 22 is also inert to the electrolyte. By way of example, the cathode membrane 84 is suitably formed of polytetrafluoroethylene in thickness from 0.125 to 2.0 miss, and the expansion membrane 22 is 12~03~;5 formed of polyethylene film having a thickness of 1-4 miss, suitably a laminated polyethylene having a thickness of 2-3 miss.
The electrolyte may be basic, neutral or acid but is preferably an aqueous solution of any one or mixture of the following: potassium hydroxide, potassium carbonate or potassium phosphate, for example a 10 percent solution of potassium hydroxide.
The cell is fabricated by machining the various grooves, shoulders and recesses within the body. The parts of the device are assembled as illustrated in Figure 2 and as explained above. The cell is inserted into the holder which connects the electrodes through an external circuit and during measurement, the outer surface of the cathode membrane is immersed in the sample being tested. The membrane permits the permeation of oxygen into the cell chamber at a rate which is proportional to the concentration of oxygen on each side of the membrane.
Since the concentration inside the cell is negligible when the cell is in dynamic equilibrium, the rate of influx of oxygen is proportional to the concentration of oxygen in the sample being tested. The oxygen reaching the cathode is reduced to form hydroxyl ions. Simultaneously, the anodically liberated lead glues ions form insoluble lead dioxide. A current corresponding to the rate of the above reactions flows in the external circuit and causes a corresponding indication on an ammeter or recorder.
It is to be understood that only preferred embodiments of the invention have been described and that numerous substitutions, alterations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, any gas analyzer cell which utilizes a gas-pervious but liquid impervious membrane to allow a measured substance to reach an anode and a cathode surrounded by an electrolyte and n which the membrane is subject to distorting internal pressures might well employ an arrangement for clamping the membrane to preclude its distortion.
Therefore, the invention should be construed in accordance with the following claims.
WHAT IS CLAIMED IS:
Jo
GAS ANALYZER
Back round of the Invention g The present invention relates to gas analyzers and, more particularly, to an improved electrochemical gas analyzer.
Various types of electrolytic oxygen sensing devices are available for use in measuring the oxygen content of gaseous mixtures and the dissolved oxygen content of fluids. Typically, these devices utilize an electrolytic cell employing a pair of spaced electrodes immersed in an electrolyte. The cells utilize an electrical parameter derived from the reduction of oxygen to determine the concentration of oxygen.
In US. Patent No. 3,429,796, an electrochemical gas analyzer is disclosed in which linearity of response is improved by use of a flat, planar mesh cathode covered with a plastic membrane.
This provides a uniform electrolyte film between the cathode and the membrane necessary for accurate response over a large range.
U. S. Patent No. 3,767,552 discloses an electrochemical gas analyzer cell which utilizes an expansion membrane and chamber to eliminate the ~240~6S
lifting of the cathode membrane in the face of quick changes of the temperature or pressure due to the fact that the internal volume changes. on upwardly protruding, uniformly curved cathode provides intimate and continuous contact with a stretched, gas-permeable cathode membrane to provide a highly stable response.
It has been found that even such a device gives incorrect results when used in environments in which the content of the measured substance includes substantial amounts of nitrous oxide because the cell acts upon the nitrous oxide to form nitrogen gas which is less permeable through the plastic cathode ; membrane than is nitrous oxide and may thus cause a substantial rise in internal volume and internal pressure, after the expansion membrane reaches its expanded limit. Also, it has been found that highly permeable background gases such as hydrogen and helium can diffuse easily into the cell and produce excessive internal volume expansions and pressures which all result in the lifting of the cathode membrane.
Jo .
~3L291~D36S
Summary of the Invention Therefore, an object of this invention is to greatly lessen the sensitivity of an electrochemical gas analyzer cell to internal pressures caused by highly permeable background gas.
This and other objectives and advantages of the invention are accomplished by a gas analyzer cell which includes an insulator body having a central passage divided into a first cell chamber and a second expansion chamber by a flexible expansion membrane. The cell chamber contains an anodic mass of. a nonpolarizable metal and is enclosed by a uniformly curved cathodic member of polarizable metal which is covered by a membrane impervious to liquid but previous to gas. An electrolyte fills the cell chamber.
The slightly upwardly protruding curved cathode and the gas permeable membrane are covered by a fibrous layer which is previous to gas and is in turn covered by a metallic mesh held in place by a ring disc held securely to the insulator body. The metallic mesh and the fibrous layer hold the cathode membrane uniformly and tightly against the cathode of the cell so that the membrane does not lift or change ISLE I
its position under conditions of increased internal pressure and, consequently, incorrect results are eliminated.
Brief Description of the Drawings The invention will be better understood by reference to the detailed description considered in conjunction with drawings in which:
inure 1 is a sectional view of the gas analyzer in accordance with the invention; and Figure 2 is an exploded perspective view of the assembly forming the analyzer of the invention.
Description of the Preferred Embodiment Referring now to Figures 1 and 2, an analyzer cell 10 is shown housed in an insulator body 14. The body 14 of the cell 10 is formed of an insulating material which in the preferred embodiment may be a thermoplastic hydrocarbon resin such as polyethylene. Such a material facilitates the formation of heat seals with various portions of the device. The cell 10 is a sealed unit adapted to be utilized until the available anodic metal is converted to an oxidized form. The cell 10 is then discarded and replaced with a new cell.
~L2~0~65 The body 14 of the cell 10 is preferably cylindrical in shape and is adapted for insertion into a holder, not shown. An axial passage 16 extends through the body 14. The passage 16 is divided into an upper electrolyte cell chamber 18 and a lower expansion chamber 20 by means of a flexible, expansion membrane 22 attached to the body 14 at a shoulder 24 of the passage 16. The membrane 22 may be sealed to the body 14 by adhesive or by heat sealing techniques. Above the shoulder 24, the passage 16 forms a broad cylindrical aperture 27 and is constricted at a flange 26 to a smaller cylindrical aperture 28. An anode 30 has its upper surface held in place by the flange 26.
The expansion chamber 20 is enclosed by an end plate 32 attached at a shoulder 34 in the passage 16 of the body 14 by adhesive or heat sealing. The end plate 32 may be formed of a rigid insulating material such as glass reinforced epoxy. A bottom surface 38 of the plate 32 is provided with an anode contact area and a cathode contact area (neither of which is shown) by plating or applying contact foil as is well known to the prior art.
The anode 30 is formed of a porous, high surface area body of a non-polarizable metal such 124(~365 as lead, cadmium, or antimony which does not react with the electrolyte. In a preferred embodiment, the anode 30 contains a central aperture 46 for rapid transmission of pressure waves or surges to the expansion membrane 22.
The anode 30 is preferably formed of lead by sistering in situ. More particularly, the particulate lead is preferably formed into a cohesive mass and is preliminarily treated to remove any oxide coating on the surfaces of the particles. By way of illustration, lead granules having an average size between 5 and 10 miss are placed within thy boy 14 in a forming tool and are covered with a 10 percent solution of potassium hydroxide. While still covered by the potassium hydroxide, the lead is compressed to shape so that the particles stinter into a cohesive mass, and the oxide coating is removed.
A contact wire 52 is connected to the anode 30. The wire 52 is threaded through a small diameter aperture 54 into a machined bore 56 extending into the side of the body 14. The wire 52 is welded to a conductive plug 58, suitably formed of stainless steel received in the bore 56. A further length of wire 60 is welded to the exterior of the plug 58.
The wire 60 is reinserted into the body 14 through an ., -12~0~65 aperture 64 below the expansion membrane 22. The wire 52 is then threaded through an aperture 66 in the end plate 32 and is connected to the anode contact on the surface 38.
The top surface of the anode 30 may be enclosed by a disc 70 of a material permeable to liquid but impermeable to solids to prevent particles that break away from the anode 30 from moving within the electrolyte into contact with the cathode and partially shorting the cell 10. The disc 70 is suitably formed of filter paper and is retained in place by a plastic washer 72 which presses the edge of the disc 70 onto the central top surface of the anode 30.
The cell chamber 18 is enclosed by a convex, perforated cathode 74. The outer edge 76 of the cathode 74 is received in a shoulder 80 on the aperture 28 of the passage 16 through the body 14. A
gas-permeable, liquid-impermeable membrane 84 is stretched over the cathode 74 and has its outer edge heat sealed in a grove 86 provided in the upper surface of the flange 26. The grove 86 may be filled with a sealant.
A connecting wire 90 is welded to the cathode 74 and is threaded through a hole 92 into a 124~365 g second bore 94 provided in the side of the cell body 14. The wire 90 is welded to a conductive sealing plug 96 received in the bore 94. An additional wire 98 is welded to the outside surface of the plug 96 and extends down and into the body 14 through an aperture 102 in the body below the expansion membrane 22. The wire 98 continues through an aperture 104 in the base plate 32 into contact with the cathode contact on the surface 38.
Since smoothness and uniformity of the outer cathode surface provides more uniform and intimate contact with the cathode membrane, it is preferred to utilize a planar, multi-apertured metal material. The planar, multi-apertured metal material may be formed from electroformed or electroetched metals or from perforated metal sheet or metal film.
The cathode surface is formed of a polarizable metal, suitably a noble metal such as gold, silver or platinum. The cathode may be formed of an inner core which is plated or coated with the noble metal. The core is preferably a resistance weldable material so as to facilitate connection to the contact wires. By way of exemplification, the cathode can be formed from brass first plated with silver and then with gold.
124036~;
The malleable cathode 74 is formed into the desired convex shape with appropriately shaped forming tools. The curvature of the cathode is sufficient to tension the membrane to assure firm contact with the cathode but does not stretch the membrane beyond its elastic limit.
The cathode 74 is preferably capable of assuming and maintaining a convex shape such that the cathode does not bend, wrinkle or distort under conditions of usage. Suitably, the gold plated, brass cathode has a thickness of 10-25 miss to provide the desired inflexibility.
The cathode membrane 84 is stretched over the cathode 74 and sealed in place. The cathode membrane 84 seals the electrolyte within the cell 10 while permitting passage of gas into the cell 10.
The membrane 84 is preferably a synthetic organic resin inert to the electrolyte and is suitably a vinyl resin such as polyethylene, polypropylene or polytetrafluoroethylene.
In order to eliminate the lifting of the cathode membrane 84 caused by an excessive pressure within the cell 10, a fibrous element 110 is positioned over the cathode membrane 84 and a second mesh element 112 of the same size and shape as the cathode 74 and constructed of nickle-plated brass is positioned there over. The element 112 is held in place by a stainless steel ring 114 held in a cavity 116 in the body 14 by stainless steel screws 118.
The element 112 is cushioned by the fibrous element 110 so that it conforms to the surface thereof and lends substantial strength to eliminate lifting of the cathode membrane 84 which might be caused by pressure in the cell 10. The fibrous element 110 is constructed of a material which is porous and therefore permeable to the gas subject to measurement. In a preferred embodiment, a porous Teflon material having a thickness of 0.010 inches and openings of approximately one to two microns is utilized.
The expansion membrane 22 is formed of a flexible synthetic resin and is provided in a thickness and of a material such that it is more flexible than the cathode membrane 84. The expansion membrane 22 is also inert to the electrolyte. By way of example, the cathode membrane 84 is suitably formed of polytetrafluoroethylene in thickness from 0.125 to 2.0 miss, and the expansion membrane 22 is 12~03~;5 formed of polyethylene film having a thickness of 1-4 miss, suitably a laminated polyethylene having a thickness of 2-3 miss.
The electrolyte may be basic, neutral or acid but is preferably an aqueous solution of any one or mixture of the following: potassium hydroxide, potassium carbonate or potassium phosphate, for example a 10 percent solution of potassium hydroxide.
The cell is fabricated by machining the various grooves, shoulders and recesses within the body. The parts of the device are assembled as illustrated in Figure 2 and as explained above. The cell is inserted into the holder which connects the electrodes through an external circuit and during measurement, the outer surface of the cathode membrane is immersed in the sample being tested. The membrane permits the permeation of oxygen into the cell chamber at a rate which is proportional to the concentration of oxygen on each side of the membrane.
Since the concentration inside the cell is negligible when the cell is in dynamic equilibrium, the rate of influx of oxygen is proportional to the concentration of oxygen in the sample being tested. The oxygen reaching the cathode is reduced to form hydroxyl ions. Simultaneously, the anodically liberated lead glues ions form insoluble lead dioxide. A current corresponding to the rate of the above reactions flows in the external circuit and causes a corresponding indication on an ammeter or recorder.
It is to be understood that only preferred embodiments of the invention have been described and that numerous substitutions, alterations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, any gas analyzer cell which utilizes a gas-pervious but liquid impervious membrane to allow a measured substance to reach an anode and a cathode surrounded by an electrolyte and n which the membrane is subject to distorting internal pressures might well employ an arrangement for clamping the membrane to preclude its distortion.
Therefore, the invention should be construed in accordance with the following claims.
WHAT IS CLAIMED IS:
Jo
Claims (7)
1. In a gas analyzer cell comprising a body having a central passage, means for expanding the volume within the cell in response to an increase in gas pressure, an anodic mass of a nonpolarizable metal positioned in the central passage, a cathodic member of polarizable metal at one end of the passage, a gas-pervious but liquid-impervious membrane covering the cathodic member external to the passage, and an electrolyte filling the central passage between the anodic mass and the cathodic member, the improvement comprising a metallic mesh covering the membrane, means which is previous to gas for separating the membrane and the metallic mesh, and means for securing the edges of the metallic mesh so that the mesh tightly overlies the membrane.
2. In a gas analyzer cell as claimed in Claim 1, the improvement in which the means for separating the metallic mesh and the membrane comprises means for providing cushioning between the mesh and the membrane.
3. In a gas analyzer cell as claimed in Claim 2, the improvement in which the means for separating the mesh and the membrane comprises a porous Teflon material.
4. In a gas analyzer cell as claimed in Claim 2, the improvement in which the means for securing the edges of the metallic mesh comprises a ring disc positioned over the metallic mesh to hold the edges thereof, the disc being secured to the body.
5. In a gas analyzer cell as claimed in Claim 1, the improvement in which the ring disc is constructed of stainless steel and is held in position by stainless steel fasteners.
6. In a gas analyzer cell as claimed in Claim 1, the improvement in which the mesh is comprised of brass metal plated with nickel.
7. A gas analyzer cell comprising a body having a central volume, an anode positioned in the central volume, a cathode positioned in the central volume, an electrolyte filling the central volume between the anode and the cathode, a passage from the central volume to the exterior of the body, a gas-pervious but liquid-impervious membrane covering the passage, and a clamp holding the membrane to the body without eliminating the transfer of gas through the passage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US75958885A | 1985-07-25 | 1985-07-25 | |
| US759,588 | 1985-07-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1240365A true CA1240365A (en) | 1988-08-09 |
Family
ID=25056232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000495539A Expired CA1240365A (en) | 1985-07-25 | 1985-11-18 | Gas analyzer comprising gas pervious/liquid impervious membrane |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS6227657A (en) |
| KR (1) | KR890000606B1 (en) |
| BR (1) | BR8505819A (en) |
| CA (1) | CA1240365A (en) |
| DE (1) | DE3540511A1 (en) |
| FR (1) | FR2585472A1 (en) |
| GB (1) | GB2178540A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0422758A3 (en) * | 1989-09-08 | 1992-10-21 | Teledyne Industries, Inc. | Electrochemical gas sensors |
| CH681179A5 (en) * | 1990-04-24 | 1993-01-29 | Ingold Messtechnik Ag | |
| US6524740B1 (en) * | 2000-03-21 | 2003-02-25 | Teledyne Technologies Incorporated | Method and apparatus for improved gas sensor |
| US7656236B2 (en) | 2007-05-15 | 2010-02-02 | Teledyne Wireless, Llc | Noise canceling technique for frequency synthesizer |
| JP5018573B2 (en) * | 2008-03-10 | 2012-09-05 | 東亜ディーケーケー株式会社 | Galvanic battery type sensor |
| US8179045B2 (en) | 2008-04-22 | 2012-05-15 | Teledyne Wireless, Llc | Slow wave structure having offset projections comprised of a metal-dielectric composite stack |
| US9202660B2 (en) | 2013-03-13 | 2015-12-01 | Teledyne Wireless, Llc | Asymmetrical slow wave structures to eliminate backward wave oscillations in wideband traveling wave tubes |
| EP2813843B1 (en) * | 2013-06-13 | 2015-12-02 | Honeywell International Inc. | Long-life, lead-free, oxygen galvanic sensor |
| EP2813844B1 (en) * | 2013-06-13 | 2017-02-08 | Honeywell International Inc. | Oxygen galvanic sensor based on noble metals |
| WO2022113389A1 (en) * | 2020-11-25 | 2022-06-02 | マクセル株式会社 | Electrochemical oxygen sensor and method for producing same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3429796A (en) * | 1965-09-16 | 1969-02-25 | Analytic Systems Co | Gas analyzer |
| US3767552A (en) * | 1971-10-06 | 1973-10-23 | Teledyne Ind | Gas analyzer |
| DE2949089C2 (en) * | 1979-12-06 | 1982-06-03 | Drägerwerk AG, 2400 Lübeck | Measuring transducer for the determination of gases in a gas mixture |
-
1985
- 1985-11-15 KR KR1019850008559A patent/KR890000606B1/en active IP Right Grant
- 1985-11-15 DE DE19853540511 patent/DE3540511A1/en active Granted
- 1985-11-18 CA CA000495539A patent/CA1240365A/en not_active Expired
- 1985-11-19 GB GB08528408A patent/GB2178540A/en not_active Withdrawn
- 1985-11-20 BR BR8505819A patent/BR8505819A/en unknown
- 1985-11-29 FR FR8517669A patent/FR2585472A1/en active Pending
- 1985-12-06 JP JP60273593A patent/JPS6227657A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3540511A1 (en) | 1987-02-05 |
| DE3540511C2 (en) | 1987-05-07 |
| GB8528408D0 (en) | 1985-12-24 |
| KR870001466A (en) | 1987-03-14 |
| FR2585472A1 (en) | 1987-01-30 |
| BR8505819A (en) | 1987-06-09 |
| GB2178540A (en) | 1987-02-11 |
| KR890000606B1 (en) | 1989-03-21 |
| JPS6227657A (en) | 1987-02-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |