Abstract: A device detects an air-fuel ratio of a fuel mixture by causing an electric current to flow through an oxygen ion-conductive solid electrolyte to cause migration of oxygen ions between an atmospheric air and a gas receiving portion into which the exhaust gases resulting from combustion of the fuel mixture are diffused via gas diffusion restricting means. The device includes means for detecting the electric current.

Abstract: An oxygen sensor (24) having an electrolyte member (72) with a thimble that is held in a metal shell (30) by an insulating member (56). The thimble has an external surface (80) and internal surface (82) that are coated with a conductive material. A sleeve (96) is attached to the metal shell (30) by spot welds (108) and a seal is established therebetween. A terminal member (120) located in sleeve (96) includes a first contact ring (142) that is connected by a spring (148) and cylinder (152) to the external surface (80) and a second contact ring (144) that is connected by a coil spring (146) to the internal surface (82). Terminals (164 and 164')carried by terminal member (120) hold a tubular housing (90) of a heater member (92). Tubular housing (90) has an end (94) that is located in the thimble of electrolyte member (72). When electrical current is supplied to heater member (92) the temperature of the thimble is maintained above a minimum operating temperature of the electrolyte member (72).

Abstract: A combination of a measuring sensor and protector having a measuring sensor with a housing and having an elongated cup-like protective pipe engaged with the housing. The pipe has a bottom having a convex shape with an inlet opening. The pipe also has at least one outlet opening spaced away from the bottom. A deflector extends inward from the pipe at an acute angle relative to a longitudinal axis of the pipe and away from the bottom so that when gas flows longitudinally within the pipe from the inlet opening, the gas is deflected by the deflector to flow around the deflector to the at least one outlet opening. The bottom also has a boss-like bulging portion projecting outward to form the inlet opening so as to reduce contamination of the measuring element by preventing solid particles in the gas from entering inside the pipe.

Abstract: An electrochemical device including a sensing element of laminar structure for determining the concentration of a component of a gas, comprising a first electrochemical cell including a first solid electrolyte body, and a first and a second porous electrode disposed on the first solid electrolyte body, a second electrochemical cell including a second solid electrolyte body, and a third and a fourth porous electrode disposed on the second solid electrolyte body, and a ceramic layer having a high electric resistance and sandwiched between the first and second electrochemical cells. In another aspect of the invention, the first solid electrolyte body is porous. In this case, the first and third electrodes are exposed to substantially the same atmosphere. In either case, the first and second, or third and fourth electrodes are disposed in alignment on opposite surfaces of the first or second solid electrolyte body. In the former case, the first and second cells serve as a pumping and sensing cell, respectively.

Abstract: A method of assembling a heated electrochemical sensor (24) for use in sensing exhaust gases in an internal combustion engine (16). A tubular electrolyte member (72) having a closed end (74) is insulated from a metal shell (30). The external surface (80) and internal surface (82) of the electrolyte member (72) are coated with a conductive material. A sleeve (96) retains a terminal member (120) having first (142) and second (144) contact rings located on shoulders (126) and (140). Terminals (164 and 164') are located in slots (160 and 162) in bore (138) on terminal member (120). A tubular heater (92) has an end (93) inserted in bore (138) until contact surfaces (161 and 163) engage terminals (164 and 164'). A coil spring (146) is placed on tubular heater (92) and a wave or washer spring (148) is placed adjacent contact ring (142). Sleeve (96) and shell (30) are brought together and spot welded (108). Thereafter, a sealed joint is produced to complete the manufacture of the heated electrochemical sensor (24).

Abstract: Apparatus and method for determining the partial pressure of a component of a fluid utilizing a probe which comprises an electrolyte with respect to the component or a constituent thereof, and to which probe the fluid is hostile. Respective interfaces of the electrolyte are disposed in contact one with the fluid and the other with a substantially non-detrimental fluid containing said component. An electric current applied between the interfaces is sufficient to transport the component through the electrolyte to said one interface and to thereby generate a local protective environment about that interface. One or more electrical parameters for the probe are continuously or periodically monitored and are utilized to derive an indication of partial pressure of the component in the hostile fluid.

Abstract: An oxygen sensor for determining an oxygen partial pressure of a measurement gas in a measurement-gas space, includes an elongate planar sensing element, a tubular protective device, and a retainer housing. The sensing element has an oxygen detecting portion adjacent to one longitudinal end thereof, and electrical terminal contacts adjacent to the other longitudinal end thereof. The tubular protective device accommodates therein the sensing element, and includes a first protective covering for protecting at least an end portion of the sensing element which is located within the measurement-gas space and exposed to the measurement gas and which includes the oxygen detecting portion. The tubular protective device further comprises a second protective covering for covering the remaining portion of the sensing element which is not exposed to the measurement gas. The tubular protective device is attached by the retainer housing to a partition wall defining the measurement-gas space.

Abstract: An enclosure for electronics, particularly adapted for implantation in the human body. The enclosure is provided with at least one transparent wall allowing it to be used in applications requiring light emission or light detection such as reflectance oximeters. The mechanical elements of the enclosure are particularly adapted to facilitate the use of welding to provide a hermetic seal for the enclosure.

Abstract: An electrochemical device of a laminar structure for determining the concentration of a component in a measurement gas, comprising: a pumping cell including a first and a second electrode disposed on a first planar solid electrolyte body; a sensing cell including a third and a fourth electrode disposed on a second planar solid electrolyte body; and a thin flat space to which the first and third electrodes are exposed and which communicates with an external space in which the measurement gas exists. The thin flat space has a diffusion resistance to the component in the measurement gas introduced through an inlet thereof.

Abstract: The invention provides an oxygen sensor for detecting oxygen concentration in exhaust gas from an internal combustion engine. The oxygen sensor comprises a closed-end tube of solid electrolyte having an inside reference electrode communicating with the atmosphere and an outside measuring electrode which is exposed to the exhaust gas, a housing to support the tube, a metallic sleeve fixed to the housing to isolate the reference electrode from the exhaust gas, while atmospheric air is allowed to enter into the tube through air passages on the metallic sleeve. The passages are protected by a filter securely fixed to the metallic sleeve, pressed by an elastic member thereagainst, whereby water or mud are prevented from entering into the tube while the sensor is operating.

Abstract: An oxygen sensor comprising an oxygen sensing unit sensitive to oxygen in an oxygen-containing gas and operative to produce an electric signal variable with the concentration of oxygen in the oxygen-containing gas when contacted by a stream of the gas, and a partitioned housing structure which has at least one first port open to the outside of the housing structure and which comprises partition means defining in the housing structure first and second chambers which are located across the partition means, the partition means being formed with at least one second port providing communication between the first and second chambers, the first chamber being open to the first port and the second chamber having enclosed the oxygen sensing unit therein.

Abstract: An oxygen sensor comprising an oxygen sensing unit sensitive to oxygen in an oxygen-containing gas and operative to produce an electric signal variable with the concentration of oxygen in the oxygen-containing gas when contacted by a stream of the gas, and a dual-shell housing structure comprising an outer shell and an inner shell enclosed within the outer shell and spaced apart inwardly from the outer shell to form a first chamber therebetween, the inner shell having defined therein a second chamber having the oxygen sensing unit fixedly held in position therewithin, the outer shell being formed with at least one port open to the first chamber and the inner shell being formed with at least one port open to the first and second chambers, the port in one of the outer and inner shells being out of alignment with the port in the other shell in a direction substantially perpendicular to the longitudinal measurement of the sensing unit and passing through a predetermined point of the sensing unit.

Abstract: A gas sensor including a gas sensor body in which is centrally inserted a gas detecting element and which permits the gas sensor itself to be attached to other members; a protective sleeve attached to an end portion of the gas sensor body; a seal member formed of a heat-resistant synthetic resin, the seal member being disposed inside an end portion on a lead wire draw-out side of the protective sleeve, with a lead wire extending through the seal member; and a spring member mounted within the protective sleeve for urging the seal member liquid-tightly against the lead wire draw-out side end portion of the protective sleeve. Since the seal member disposed in an end portion of the protective sleeve is formed of a heat-resistant synthetic resin, the durability thereof is improved even where high temperature gases such as the exhaust gases of internal combustion engines or the like are to be detected.

Abstract: A solid state electrochemical ceramic cell adapted to alter the composition of gas exhaust streams containing noxious component passing therethrough comprising: a porous, high surface area body having a gas-receiving first end seal portion, a gas egressing second end seal portion and substantially gas impervious side walls defining the length of the cell; a high surface area, porous solid electrolyte forming the body of the cell interior; a gas communicating passageway through the cell length extending from the first seal end portion through the second seal end portion and adapted to carry gas through the length of the cell; a first electronically conductive region and a second electronically conductive region, said regions disposed in electronically opposing segment of the cell; a first electrode connection member located in said first conductive region and a second opposing electrode connection member located within said second conductive region; said end seal portions adapted to be positioned in gas-tight

Abstract: Apparatus for sensing oxygen concentration using a solid electrolyte of cylindrical shape, with a heater disposed within the solid electrolyte, is disclosed. The member supporting the heater, and the leads for the heater, are integrally bonded to the heater through an inorganic bonding member such as glass. By integrally bonding the support member and leads through an inorganic bonding member, the heater length can be reduced.

Abstract: An electrochemical device comprising at least one electrochemical cell having a planar solid electrolyte body, and a first and a second electrode one of which is disposed on the solid electrolyte body. The device has a measurement-gas space communicating with an outside space for introducing a measurement gas, and a reference-gas space into which a reference gas is introduced. The first and second electrodes are exposed to the measurement-gas and reference-gas spaces, respectively. The measurement gas is introduced into the measurement-gas space with a diffusion resistance to molecules of a selected component of the measurement gas. The measurement-gas and reference-gas spaces are juxtaposed in spaced-apart relation with each other in substantially the same plane parallel to the planar solid electrolyte body.

Abstract: An apparatus for determining oxygen concentration in exhaust gases from an automotive engine is provided which includes a solid electrolytic member of oxygen ion conductive material disposed between a pair of first and second electrodes. In this apparatus, a porous insulating layer is formed on a cylindrical heater made of ceramics and a first electrode is formed on the outer periphery of the porous insulating layer. A solid electrolytic member is formed as a thin film form on the outer periphery of the first electrode layer and a second electrode is formed on the outer periphery of the solid electrolytic film member. Since the solid electrolytic film is formed such that it overlies the outer periphery of the cylindrical heater, it has an adequate structural strength even if formed to be a thinner film.

Abstract: To provide an easily manufactured and easily connected heater element for a tubular ion-conductive body (26) forming a sensing element (24) of the oxygen sensor, the heater element (35) comprises a plate-like substrate (36) of insulating material, e.g. ceramic, which, at its inner end is wider than at the end fitting into the inside of the tubular ion-conductive body, the conductors leading to the heater being formed as conductive tracks spaced apart from each other by a greater distance at the inner end, adjacent connection zones (37/3), than close to the heater zone (37/1), the plate-like substrate, at the inner portion, being essentially trapezoidal and terminating in an end edge (36') which forms the wider side of the trapezoid.

Abstract: The air-fuel-ratio sensor has a mounting body, a cup-shaped protector enclosing a sensitive element, and gas passage holes and deflectors are provided on the protector wall in such a manner that a gas stream outside the sensor generates swirl of the gas in the cup-shaped protector, the amount of the swirling gas increasing with the distance from the mounting body.

Abstract: A rodlike ceramic member of a heater projects towards and into the active tip of the solid electrolyte tube of an oxygen sensor, extending out from the bottom end of the principal insulating member of the sensor which is made of the same ceramic material. Conducting paths of the heater are brought up to a shoulder where the wider insulating part joins with the carrier of the heater, for connection with conductors leading to the end of the main insulator which is remote from the measuring gas and, furthermore, on this shoulder, connections are also made between conducting paths of the solid electrolyte sensor probe and conductors leading to the end of the main insulator remote from the measuring gas. At that end of the main insulator, sleeve connections are made to connection wires for external connections.

Abstract: The probe comprises an outer casing communicating through apertures with the atmosphere of a furnace and bearing a support part on which the measuring electrode, or anode, is wound. A tablet of solid electrolyte in contact with the anode can be easily and quickly replaced when the measuring face thereof has become contaminated by the furnace atmosphere. The reference electrode, or cathode, is formed by the soldered junction and one of the wires of a thermocouple, the two conductors of which are crumpled into a hollow in the reference face of the tablet, then pass through a conduit of insulating refractory material. Between the bottom of the casing and that of a tubular support accommodated therein there is a spring which has the effect of pressing the tablet against a washer via the supporting part, thus sealing the furnace atmosphere from a reference atmosphere.

Abstract: An oxygen sensor includes a planar oxygen sensing element having an oxygen detecting portion located in the vicinity of one end thereof, and a protective covering encloses the sensing element to protect the detecting portion in particular. The detecting portion has an oxygen detecting member exposed to a measurement gas. The sensing element has opposite primary surfaces having a larger area than other surfaces thereof, and the detecting member is disposed on the side of one of the primary surfaces. The protective covering has apertures for allowing the measurement gas to flow through a wall of the protective covering so that the detecting member is exposed to the measurement gas. The apertures are formed through a part of the wall of the protective covering which does not face the above-indicated one primary surface of the planar sensing element.

Abstract: An oxyen sensor for determining an oxygen partial pressure of a measurement gas in a measurement-space, comprising (a) an elongate oxygen sensing element having an oxygen detecting portion adjacent to its one longitudinal end, (b) a first protective covering for protecting at least an end portion of the sensing element which is located within the measurement-space and exposed to the measurement gas and which includes the oxygen detecting portion; (c) a second protective covering for covering another portion of the sensing element which is not exposed to the measurement gas; and (d) a retainer housing for supporting the sensing element, and the first and second protective coverings such that the end portion of the sensing element having the detecting portion is located within the conduit. The first and second protective coverings consist of an integral protective tubing member which is supported by the retainer housing with fluid tightness therebetween and which accommodates the oxygen sensing element.

Abstract: An oxygen probe for measuring the characteristics of furnace gases. The probe includes electrodes of a long lasting and relatively inexpensive nickel containing alloy. The probe is formed with apertures and internal passages for ventilating the three phase contact zones between gas, electrolyte, and electrodes with furnace gases, thereby minimizing errors due to catalytic reactions at the electrodes. The probe sheath may be composed of the same alloy as the electrodes, and the electrodes may be fabricated as an integral part of the sheath, so that the sheath serves both as a structural member and as an electrical conductor for conducting voltage generated within the electrodes. A gas pump may be used to assure adequate ventilation to the electrode-electrolyte interfaces.

Abstract: A feedback control is effected during warming-up operation so as to adjust an actual air-fuel ratio to a target value. A sensing element is used to probe exhaust gases to detect an air-fuel ratio of a fuel-rich mixture that is required for warming up the engine. The amount of fuel injection is corrected so that the actual air-fuel ratio is adjusted to a target value displaced to the rich side from the stoichiometric ratio.

Abstract: An electrochemical device comprising at least one electrochemical cell having a planar solid electrolyte body, and a first and a second electrode one of which is disposed on the solid electrolyte body. The device has a measurement-gas space communicating with an outside space for introducing a measurement gas, and a reference-gas space into which a reference gas is introduced. The first and second electrodes are exposed to the measurement-gas and reference-gas spaces, respectively. The measurement gas is introduced into the measurement-gas space with a diffusion resistance to molecules of a selected component of the measurement gas. The measurement-gas and reference-gas spaces are juxtaposed in spaced-apart relation with each other in substantially the same plane parallel to the planar solid electrolyte body.

Abstract: An oxygen sensor according to the present invention comprises a tumbler-shaped solid electrolytic element formed of an oxygen-ion-conductive metal oxide. A first electrode and a lead electrically connected thereto are formed on the outer peripheral surface of the element which is exposed to exhaust gas. A second electrode is fixed to the inner peripheral surface of the element which is exposed to the atmosphere. The element is held by a ring-shaped metallic holder. The holder and the first electrode are electrically insulated from each other. A conductive metallic pipe member is disposed between the element and the holder. One end of the pipe member is electrically connected to the lead by means of a conductive metal ring. A partition wall extends integrally from one end of the pipe member, defining between its inner surface and the other peripheral surface of the element a space for housing the conductive metal ring between the pipe member and the lead.

Abstract: A rod-like electrical heating element is incorporated in the interior of a tubular solid electrolyte sensor connecting zones of the heating element are disposed on the end face thereof remote from the sensing end. Electrical connecting parts are pressed against the connecting zones of the heating element by means of a spring element. These electrical connecting parts are in electrical contact with the connecting cable of the gas sensor via conductor wires, leads or other connecting means.

Abstract: A gas measurement probe has a casing (11) equipped with a closure shell (17) on its end away from the gas to be measured. At the other end of the casing, within its longitudinal bore, a sensor element (24) is held fast and tight in the casing. A rod-shaped part carrying a heater element fits within the sensor element and extends out of it at its end away from the gas to be measured to an extremity near which contact areas are provided on its periphery. On these contact areas, resilient connection wires lie under mechanical bias. These wires, between the loops bearing against the contact surface and their ends are bent in Z or sinuous shape so as to secure them against pulling, twisting and shaking forces. These connection elements and also another conductor running in the probe cooperate with an indexing feature of the rod-shaped element, such as a suitable groove to secure the rod-shaped component against twisting.

Abstract: The invention provides a method for the continuous monitoring of the oxygen or hydrogen concentrations in a steam system with a solid electrolyte oxygen analyzer. The operating temperature of the analyzer is adjusted to about 500.degree. C. and the reference gas used for the analyzer is air or oxygen-inert gas mixture. Under operating conditions, an oxygen or hydrogen level of low parts per billion in superheated or saturated steam can be identified and measured. This technique is specifically useful for continuously monitoring the air inleakage, that is, the oxygen contents in steam and for controlling the corrosion intensity that is, the hydrogen levels in steam in, for example, steam turbine systems in power plants.

Abstract: An exhaust gas sensor (10) is disclosed which includes a sensor element (12) and a member (48). The member (48) includes a hollow tube (50) and a seal disk (58). The seal disk (58) is urged into sealing engagement with an annular surface (14) on the sensor element (12) to prevent exhaust gas from entering the interior (26) of the sensor element (12). The inner electrode (22) of the sensor element (12) extends to the annular surface (14) in an annular ring (88). The seal disk (58) is permitted to contact the inner electrode (22) about the entire periphery of the ring (88).

Abstract: An oxygen sensor having a bar-shaped heater inserted in an elongate bore formed in a tubular solid electrolyte body which has porous platinum electrodes on its inner and outer surfaces and which is supported by a housing such that its closed end portion is exposed to exhaust gas and such that the elongate bore is gas-tight with respect to the exhaust gas. The bar-shaped heater comprises a heating resistor having a positive temperature coefficient, a ceramic body carrying the heating resistor so as to embed the latter, and a pair of lead wires. The ceramic body has on its periphery a pair of terminal pads connected to the heating resistor. The ends of the lead wires are brazed to the pads with a mass of brazing material containing silver. An exposed surface of the brazing mass is coated with a metal layer made of metal which is different from silver or its alloy. The metal layer may be further coated with a heat-resistant layer.

Abstract: The oxygen sensor for exhaust gas of internal combustion engine includes a solid electrolyte tube having an inner electrode coated on the inner surface of said electrolyte tube outer electrode formed on outer surface of said electrolyte tube and disposed on the outside surface thereof so as to come in contact with exhaust gas and a metallic protective tube coaxially surrounding said electrode with a spacing therefrom. The sidewall of the protective tube has two similarly arranged matrices of holes, each hole being made by cutting an arcuate edge on the sidewall and bending the thus cut portion toward the inside of the protective tube, and the holes of one matrix are interposed among the holes of the other matrix while being offset therefrom in both the longitudinal and circumferential directions of the protective tube.

Abstract: The disclosed oxygen sensor includes three plate-like elements disposed in parallel and a heater, i.e., an oxygen pump element with electrodes and said heater disposed adjacent thereto, an oxygen concentration cell element with electrodes, and an insulating board disposed between the first two elements and having a hole bored therethrough at a position between the opposing electrodes of the first two elements so as to define a cavity therebetween, said insulating board further having at least one passage communicating said cavity to outside of said oxygen sensor.

Abstract: To provide access of gases to an electrode (39, 48) positioned on a flat plate (35) of solid electrolyte material, under controlled conditions, and while preventing access of gases to the electrodes where not desired, the electrodes are covered with a porous cover layer (42, 49) of sintered granular material, for example of zirconium dioxide, having a grain size of 10 .mu.m, and 25 .mu.m thick, with void or pore-formation material added thereto which, upon sintering, becomes volatile and leaves a porous structure. A gas-tight tunnel covering (44, 51) extends over the electrode and filler covering leaving an open space in those regions where the electrode is exposed to the desired gas, for example a test gas adjacent the sensing end (11/1) of the sensor, or oxygen from ambient air adjacent the connecting or terminal end (11/3) of the sensor, the respective gas to be applied to the electrode diffusing through the pores of the porous structure to the respective electrode.

Abstract: A process and apparatus for the determination of the activity of carbon in furnace atmospheres involves the measuring of the ratio of the partial pressure of oxygen in the furnace gas with respect to a reference gas with the aid of an electric potential furnished by oxygen ion conducting solid state cells. The reference gas comprises the furnace gas brought into a Boudouard equilibrium at the furnace temperature. The exchange takes place in a comparison chamber with a time constant 1/10 of that of the furnace. Thus, the activity of carbon may be calculated or calibrated by a formula which includes the electric potential furnished by the solid cells and the absolute temperature, but which does not include the CO content or the pressure. The process may thus be operated without regard for the CO content in the furnace atmosphere.

Abstract: Disclosed is a gas leak detector comprising; a tubular gas-sensitive element defining openings at both ends thereof, one end being a gas inlet and the other end a gas outlet, and made of an oxygen-ion conductive solid electrolyte; a set of electrodes provided respectively on the inner and outer walls of the gas-sensitive element, the electrode on the outer wall being kept in contact with a reference gas; a heater adapted to heat the gas-sensitive element to a predetermined temperature at a location corresponding to the set of electrodes; and a catalytic layer provided on the surface of the electrode on the inner wall being kept in contact with a target gas.

Abstract: An oxygen sensor whose sensing element is covered by a cylindrical porous filter cap, prepared by sintering metallic wool such as nickel-chromium alloy wool for protecting the sensing element from damage by mechanical shock and thermal shock due to a high flow pressure of a high temperature gas and for easy determination of sensing response time.

Abstract: The reference gas of an electrochemical cell is vented into the process gas being measured at a location sufficiently close to the cell to maintain the gas pressure of the reference gas equal to the gas pressure of the process gas. A packing gland for securing a sensor cell within a support member for high temperature applications is also disclosed.

Abstract: A thin film solid electrolyte cell structure for use as an oxygen sensor, a combustibles sensor and a gross-oxygen-gross-combustibles sensor. An electrode is sealed to a porous mechanical support member by a thin film solid electrolyte which also seals the support member. The sealed support member divides a sensor apparatus into two zones, one of which contains a reference gas, the other of which contains the gas to be measured.

Abstract: A leanness sensor has a sensor element made of an oxygen-permeable solid electrolyte and having a cylindrical form or a form like a vessel closed at one end thereof. The sensor element is provided with metallic electrodes formed on the inner and outer surfaces thereof. An inner metallic member and an outer metallic member are mounted on the sensor element and electrically connected to the metallic electrodes. The sensor element is fixed to the inner side of the end portion of a cylindrical insulating tube.

Abstract: A combustion sensing apparatus having a solid electrolyte disposed in the vicinity of a burner and having a tabular form. Thanks to the tabular form of the solid electrolyte, the production of the apparatus is very much facilitated and the areas occupied by the anode and cathode are minimized. The construction of the apparatus as a whole is simplified and the reliability of the same is improved remarkably. In addition, the cost of production is lowered advantageously.

Abstract: To prevent signal degradation of a sensing element, which may be a potentiometric or a polarographic sensor, having a reference electrode exposed to ambient air, the reference electrode (22) is placed within a chamber (21) which has included therein granules (39) of a material inert with respect to oxygen and having a surface hardness at least as hard as the reference electrode (22) so that, upon subjection of the sensor, when coupled to the exhaust system of an internal combustion engine, to vibrations, shocks and jolts, the granules will move in the chamber, rub against the electrode, and hence keep the electrode surface activated and free from contamination which may have penetrated with ambient air.

Abstract: An oxygen meter for measuring the oxygen concentration in a measured gas, having a probe type detecting section carrying at its end a solid electrolyte unit constituting a partition wall, so as to produce a signal corresponding to the difference in the oxygen concentration between the inner side and the outer side of the partition wall. The oxygen meter is adapted to be exposed to the flow of the gas to be measured or into a furnace through a hole formed in the furnace wall, thereby to continuously produce a signal representing the oxygen concentration in the gas to be measured.

Abstract: A dual gas measuring solid electrolyte apparatus employing a common oxygen ion conductive solid electrolyte membrane provides an electrical signal indicative of a selected anhydride of a monitored gas environment and an electrical signal indicative of the oxygen content of the monitored gas environment.

Abstract: In a solid electrolyte electrochemical cell device for generating an EMF signal based on the Nernst equation which is indicative of the SO.sub.2 content of a monitored gas environment, the oxygen content of the reference environment of the cell is adjusted to maintain it equal with the oxygen content of the monitored gas environment to eliminate the effect of oxygen on the EMF signal measurement of SO.sub.2.