Abstract: A gas concentration measuring apparatus is provided which measures the concentration of two kinds of gas components such as O2 and NOx contained in exhaust gasses of an internal combustion engine of automotive vehicles. The apparatus has a gas sensor which includes a first cell responsive to application of a voltage to discharge O2 in the exhaust gasses to the outside and produce an electric current as a function of concentration of the discharged O2 and a second cell responsive to application of a voltage to produce an electric current as a function of concentration of NOx in the exhaust gasses from which the O2 is discharged by the first cell. The apparatus offsets an error component of the electric current produced by the second cell which depends upon O2 contained in the exhaust gasses, or which in related operations, depends upon any residual oxygen remaining in the second cell without being discharged by the first cell.

Abstract: A hand-held vehicle exhaust analyzer for testing gas content in exhaust emitted from a vehicle is disclosed. The vehicle exhaust analyzer is of a size and weight to be held in a user's hands. The system includes a housing with an inlet receiving exhaust emitted from the vehicle. A sensor assembly is disposed in the housing, receives the exhaust emitted from the vehicle through the inlet, and determines the content of a plurality of different gases in the exhaust. A control system is disposed in the housing and is operatively coupled with the sensor assembly to regulate operations of the sensor assembly and to receive and interpret results of operations of the sensor assembly. A power supplying apparatus is disposed in the housing to deliver power throughout the system. The housing, and all components disposed in the housing have a combined weight of no greater than about five pounds.

Abstract: There are provided with a gas detecting sensor and a gas detecting device for controlling a ventilation system of a vehicle using the gas detecting sensor. The gas detecting sensor of the present invention includes two kinds of gas sensing layers separately formed and a heater assembly for heating the two sensing layers to different temperatures.

Abstract: An oxygen sensor for determining the oxygen concentration in the exhaust gas flow of an internal combustion engine. The sensor includes an outer electrode exposed to the exhaust side and a reference electrode exposed to the ambient air. In the sensor, a space adjacent to the reference electrode or surrounding the reference electrode has an adsorbing and/or absorbing agent, which is introduced, for example, in a loose powder packing or a multiple pellet packing. Other versions of the novel oxygen sensor also have an oxygen supplying material, such as, for example, Mn-oxide, Ba-oxide and/or Ce-oxide, to help promote combustion of exhaust gas components/pollutants and any residue chemicals left remaining from the sensor manufacturing process.

Abstract: The present invention provides apparatuses and processes for the measurement of hydrogen in aqueous solution at concentrations as low as about 0.1 nM. The present invention is capable of accurately and reproducibly measuring the concentration of dissolved hydrogen in an aqueous solution that also contains other dissolved gases, such as oxygen, carbon monoxide and sulfur compounds, such as hydrogen sulfide. In a presently preferred embodiment of a hydrogen analyzer 38 of the present invention, water containing dissolved hydrogen is equilibrated with a carrier gas by means of gas flow through a mass transfer device 10.

Abstract: A method and apparatus for real time gas analysis involving determining individual concentrations of fluid constituents in a mixture of known constituents by measuring properties of the mixture and solving a set of equations, which relate the individual gas concentrations to the measured properties of the mixture, for the unknown individual gas concentrations. The individual concentrations of four gasses in a mixture are determined by: passing the mixture through a flowmeter, a capillary, an orifice, and a sonic oscillator; transducing temperature, pressure and acoustic frequency measurements taken from the sensors; determining the density, viscosity, and the specific heat of the mixture; forming three equations which respectively relate these three properties to individual gas concentrations; and solving the three equations and the constitutive equation which requires that the sum of the concentrations equal unity, for the four unknown individual gas concentrations.

Abstract: A portable medical gas system tester is small, lightweight, sturdy, self-contained and portable and can be either pen-activated and/or voice-activated so that it can be operated in the field by just one person. The device can test, collect and interpret data from all medical gas components, such as outlets, valves, alarms, central sources of supply and emergency low pressure oxygen fill connections, and with all medical gases including oxygen, air, vacuum, waste anesthetic gas disposal, nitrous oxide, nitrogen, carbon dioxide and carbon dioxide/oxygen mixtures. The device has a computer, a digital display device, an analog to digital converter, a gas sensor, a pressure and vacuum transducer coupled to the gas sensor, and an oxygen transducer coupled to the gas sensor, an exhaust outlet for venting excess gases to outside of the device's case, a bi-directional flow sensor coupled to gas sensor, and a flow transducer coupled to the flow sensor.

Abstract: In an exemplary embodiment, the present invention provides an exhaust constituent sensor comprising a planar sensing element securely held in place within a tubular inner shield by known methods. Improved thermal management of the sensor is provided by disposing a thermally conductive material between said planar sensing element and said tubular shield. In an exemplary embodiment, the thermally conductive material comprises a high thermal conductivity metal mesh which transfers heat within said tubular shield to said tubular shield via thermal conduction. The heat is then dissipated into the surrounding environment via thermal convection at an outer surface of the tubular shield. By optionally disposing an annular heat fin on the outer surface of the tubular shield, a greater amount of heat is dissipated into the surrounding environment via thermal convection in less time.

Abstract: A system for measuring the non-methane HC concentration of gas sample, e.g., automotive exhaust gas, comprises a sensor catalyst capable of selectively oxidizing the combination of CO+H2+alkene hydrocarbons in a gas sample and a catalytic differential calorimetric sensor downstream of the sensor catalyst, capable of producing an output signal representative of the exothermic effect of oxidation of the remaining aromatic and alkane hydrocarbons in the gas sample. The system also includes a heater for maintaining both the sensor catalyst and the catalytic calorimetric sensor at a temperature sufficient to achieve substantially complete oxidation of the CO+H2+alkene hydrocarbon combination and the aromatic and alkane hydrocarbons, respectively. Lastly, the system includes a means for analyzing the output signal representative of the concentration of unburned aromatic and alkane hydrocarbons in the exhaust gas to determine concentration of the total non-methane hydrocarbon species.

Abstract: A gas sensor array for detecting individual gas constituents in a gas sensor, said array being composed of a carrier member of a non-conductive substrate having a plurality of individual sensor elements formed by semiconductor oxides being applied thereon in a planar arrangement and the array is provided with contact electrode arrangements for measuring electrical conductivity, with a heating arrangement for heating a predetermined operating temperature and with protective sheaths for protecting the arrangement against external influences along with a fastening base so that the individual operating temperatures allocated to the various sensors and wherein the differences between respective sensor signals are formed for detecting the individual gas constituents, with these differences being supplied to a processing unit. In a preferred embodiment, at least one part of the individual sensor element is composed of a &bgr;-Ga2O3 thin film.

Abstract: A sensor for determining an oxygen content of an exhaust gas of an internal combustion engine includes a flat-plate sensing element that is inserted in a gas-tight fashion via a hybrid seal in a ceramic shaped element that is arranged in a metal housing. The seal includes a powdered sealing packing, both placed around the sensing element in a recess at one end of the ceramic shaped element and a fusible glass seal located above the powdered sealing packing. The seal achieves gas-tight and gasoline-resistant isolation or immobilization of the sensing element in the ceramic shaped element.

Abstract: An air-fuel ratio control system for a gas-fueled engine which is capable of achieving the combustion in a target air-fuel ratio to surely purify an exhaust gas through an exhaust purification catalyst. In the air-fuel ratio control system, a three-way catalytic converter is placed in an exhaust pipe of the engine and an O2 sensor is located on the upstream side of the three-way catalytic converter. The O2 sensor comprises an element, and an atmosphere side electrode is formed on an inner surface of the element while an exhaust gas side electrode is formed on an outer surface thereof. The exhaust gas side electrode is coated with a catalyst layer which can remove hydrogen through a catalytic reaction. A control unit of the control system controls a fuel supply quantity by a gas injector using a feedback correction coefficient on the basis of the output of the O2 sensor, thereby reducing the deviation between an air-fuel ratio measured by the O2 sensor and a target air-fuel ratio.

Abstract: A hybrid integrated circuit of a gas sensor, comprising a substrate (1) in the form of a ring-shaped peripheral portion (2) and a disk-shaped central portion (3), both being interconnected through three jumpers (4) spaced 120° apart and having three branchings (10) arranged at 120° at the peripheral portion (2). The central portion (3) carries a gas-sensitive film (7), a film heater (6), and a film electrode (8) of the circuit for measuring the resistance of the gas-sensitive film (7). The heater (6) and the electrode (8) are electrically connected along the jumpers (4) to bonding pads (5) located in the peripheral portion (2). The thickness of the jumpers (4) and of the central portion (3) is 0.15-0.25 mm, and the width of the jumpers (4) is 0.05-0.15 mm.

Abstract: An apparatus adapted for analyzing exhaust emissions by using a small fraction of a continuously-extracted exhaust sample combined with a pollutant-free diluent through a system of critical flow orifices at a predetermined and precisely controlled flow ratio. A small quantity of gas is extracted from the diluted exhaust gas available which is diluted with the contaminant-free air or nitrogen to produce a mixture having a dew point below ambient air temperature and satisfying the flow requirements of the analysis system. The diluted sample may then be analyzed to obtain the total mass of pollutants through identification of the instantaneous exhaust concentration rate and the exhaust mass flow rate or through identification of the concentration of pollutants collected in a sample bag and the total exhaust volume.

Abstract: The present invention discloses an integrated ethanol gas sensor and fabrication thereof. The present invention utilities micro electro mechanical system (MEMS) technology and has a main sensing part in the form of a cantilever-bridge structure made of SiC thin film material arranged over a silicon substrate. The present invention integrates an SiC heater of comb or finger electrode shape and an SnO.sub.2 thin film gas sensing element applied over distinct portions on the same Si substrate together with Al2O3 and SnO2 thin films via a VLSI technology.

Abstract: A method and apparatus is provided for modulating the flux of oxygen impinging on a calorimetric gas sensor. The method and apparatus are based on modulating the oxygen concentration of a gas mixture presented to the microcalorimeter between a predetermined high level and at a substantially zero value to create a modulated output to reduce the noise of the sensor and to eliminate its zero-offset.

Abstract: A stable sensor designed to detect accurately the total NOx concentration under 100 ppm in terms of the NO gas concentration is made up of a first cell and a second cell with a gas diffusion aperture provided between the two cells. The first cell has a partition wall of a substrate of oxygen ion conductor containing zirconia as the main component and permitting a gas to be detected to enter the zirconia substrate; oxygen pumping electrodes are also formed on the first cell substrate which functions to expel oxygen in an atmosphere of the first cell to the outside and to reduce NO.sub.2 of the NOx gas to be detected to NO gas.

Abstract: A multilayered gas sensor for detecting the presence of gases in air. In particular, sensors are described for sensing hydrocarbons and nitrogen oxides. An additional feature of the invention is to provide a device that is suitable for sensing gases in the harsh environment of an automobile exhaust system. The device features a ceramic substrate and a glass layer to adhere a catalyst support to the substrate. A catalyst layer of either platinum or rhodium is deposited on the catalyst support and a thermally sensitive resistor element detects reactions of hydrocarbons or nitrogen oxides on the corresponding catalyst.

Abstract: A gas sensing device having a semiconductor substrate, wherein the semiconductor substrate is covered by an insulator layer, on which an intermediate layer is formed, and subsequently covered by a gas sensing catalytic layer, wherein the intermediate layer and the catalytic layer are made of different materials. The gas sensing device may optionally have dispersed between the insulator layer and the intermediate layer a catalytic metal layer. The gas sensing device provides improved stability and speed of response, even when used at high ambient temperatures, such as temperatures found in combustion systems. A method for making the gas sensing device is also disclosed.

Abstract: An NOx-concentration detecting apparatus is disclosed which enables a user to readily know a record of operating conditions of an NOx sensor. The apparatus includes an NOx sensor, pumping-current control means, constant-voltage application means, NOx-concentration detecting means, a heater and writing means for writing to a recorder variation of at least one parameter selected from a first pumping current value, a second pumping current value, the concentration of oxygen contained in the measurement gas and the concentration of NOx in the measurement gas. Also disclosed is an NOx-concentration detecting apparatus capable of determining the concentration of NOx at a high resolution even when different NOx sensors are used. The NOx-concentration detecting apparatus detects the first pumping current I.sub.P1, and the second pumping current I.sub.

Abstract: A method and apparatus for real time gas analysis involving determining individual concentrations of fluid constituents in a mixture of known constituents by measuring properties of the mixture and solving a set of equations, which relate the individual gas concentrations to the measured properties of the mixture, for the unknown individual gas concentrations. The individual concentrations of four gasses in a mixture are determined by: passing the mixture through a flowmeter, a capillary, an orifice, and a sonic oscillator; transducing temperature, pressure and acoustic frequency measurements taken from the sensors; determining the density, viscosity, and the specific heat of the mixture; forming three equations which respectively relate these three properties to individual gas concentrations; and solving the three equations and the constitutive equation which requires that the sum of the concentrations equal unity, for the four unknown individual gas concentrations.

Abstract: In order to determine a concentration of a gas mixture, especially a hydrogen concentration of a containment atmosphere of a nuclear power station, a temperature change resulting from a catalytic reaction is measured. The gas mixture is diluted with a motive gas of known composition. The dilution is carried out by a jet pump.

Abstract: A differential calorimetric gas sensor (10) which includes a sensing element (12) having a catalytic layer (14) disposed on a multi-layered substrate (26). Catalytic layer (14) includes an active catalyst region (14a) which oxidizes total combustibles within an exhaust gas stream and a reference catalyst region (14b) which oxidizes selective combustibles within the exhaust gas stream. An electrochemical oxygen source (18) is disposed on an opposite side of multi-layer substrate (26) from sensing element (12). An oxygen sensor cell (170) may be incorporated into electrochemical oxygen source (18). The multi-layered substrate (26) includes a plurality of overlaying insulating layers in which an intermediate layer (60) and a bottom layer (64) support primary heaters (58, 62), and in which another intermediate layer (52) supports compensation heaters (50a, 50b).

Abstract: The invention includes systems and methods which allow reactivation of supported noble metal catalysts. The method involves heating the catalyst in the presence of a gaseous hydrocarbon in the absence of oxidizing agents. Systems of the invention provide for in situ reactivation of catalytic material.

Abstract: A system for measuring the non-methane HC concentration of gas sample, e.g. automotive exhaust gas, comprising first and second catalytic differential calorimetric sensors. The first catalytic differential calorimetric sensor is capable of producing a first output signal representative of the exothermic effect of the oxidation of the predominate oxidizable species (CO+H.sub.2 +non-methane HC combination) in the gas sample. The second catalytic differential calorimetric sensor is capable of producing a second output signal representative of the exothermic effect of the combined oxidation of the CO+H.sub.2 +alkene hydrocarbon species in the gas sample. Lastly, the system includes a means for comparing the first output signal with the second output signal, thereby indicating the total concentration of unburned aromatic and alkane hydrocarbon species in the gas sample which directly correlates to the total non-methane HC concentration.

Abstract: A hydrogen sensor including a piezoelectric device with a hydrogen-interactive metal film that reversibly interacts with hydrogen to provide a correspondingly altered frequency response characteristic, relative to the frequency response in the absence of hydrogen. The piezoelectric device may be for example a quartz microbalance or a surface acoustic wave device, having a thin film (e.g., 10-100,000 Angstroms thickness) coating thereon of a hydrogen-interactive metal such as palladium, platinum, nickel or the like.

Abstract: A catalytic structure may be in the form of a ceramic support member having disposed on it a catalytic material which is a fired coating (124a-1, 124a-2) of a catalytic ink. The catalytic ink contains a liquid vehicle, at least one metal resinate compound and fine particles of a refractory metal oxide having dispersed thereon a catalytically effective amount of a catalytic metal component such as platinum or palladium or combinations of two or more catalytic metal components. The resulting catalytic structure may be employed as a catalytic gas sensor (24, 124) and further may include at least one conductor member (130, 132) which provides both temperature sensing of the fired catalytic coating (124a-1, 124a-2) to ascertain the degree of reaction taking place at the surface thereof, and heating of the support member to heat the fired catalytic coating to a temperature high enough to promote the catalytic reaction.

Abstract: A sensor housing (10) for directing the flow of a gas over two sensitive regions (53, 54) of sensing device (52) includes an inner shroud (12) surrounding the sensing device (52). The inner shroud (12) is inserted into an outer shroud (14), such that a plurality of gas channels (44) are formed between the inner shroud (12) and the outer shroud (14). In operation, a gas enters through inlet orifices (28) in the outer shroud (14) and travels through the gas channels (44) to the proximal end (26) of the inner shroud (12). The flow direction of the gas is then reversed and the gas passes through an inner chamber (50) and over sensitive regions (53), (54) located on the surface of the sensing device (52). Vacuum pressure created at an outlet hole (46) located at a distal end (35) of the outer shroud (14) draws the gas out of the inner chamber (50) and return the gas to the exterior of the sensor housing (10).

Abstract: The present invention and its claims encompass principles, methods, apparatus, and applications for detection, quantification, and monitoring of responses of gases, vapors, aerosols, and mixtures thereof to initiators of exothermic reactions. While the invention can be utilized for any concentration level, the intended, normal utilization is for gases in which the concentrations of species capable of participating in exothermic chemistry are too low to support self-sustaining exothermic reactions leading to detonations or deflagrations as well as for gases in which other factors prevent the exothermic reaction chemistry from becoming self-sustaining. This abstract shall not be construed to define or limit in any way the scope of the invention, which is measured by the appended claims.

Abstract: A vehicle gas analyzing system for testing gas content in exhaust emitted from a vehicle is disclosed. The vehicle gas analyzing system is of a size and weight to be held in a user's hands. The system includes a housing having outer dimensions no greater than about 12".times.8".times.3", and has an inlet receiving exhaust emitted from the vehicle. A sensor assembly is disposed in the housing, receives the exhaust emitted from the vehicle through the inlet, and determines the content of a plurality of different gases in the exhaust. A user interface is disposed on an outside surface of the housing, allowing a user to input instructions to the system and to perceive output from the system.

Abstract: Oxygen sensor for measuring resistance as a function of oxygen partial pressure, made of alkaline-earth-doped perovskitic lanthanum ferrites with the general formulaLa.sub.1-x Me.sub.x FeO.sub.3-.delta.where Me is one of alkaline earth metals, Mg, Ca, Sr, and Ba, x is a degree of doping of the lanthanum ferrites. The oxygen sensor oxygen deficit of anion is 6=0 to 0.25, and the degree of doping of the lanthanum ferrites is x=0.1 to 0.3 and is selected to provide a temperature independent resistance property to the oxygen sensor in a lean range.

Abstract: A system is provided in an exhaust emission sampling system for controlling a flow controller in order to compensate for the effects of changing water vapor content in a diluted sample having a predetermined dilution ratio. A water measuring device such as a relative humidity sensor generates a water vapor signal based on the amount of water vapor in the diluted sample. The water vapor signal is then processed within a control unit to obtain a value for the amount of water in the diluted sample. A control signal is generated by the control unit based on the amount of water vapor, flow rate of the exhaust emissions, and also, on the type of fuel used in the combustion process to control the flow controller which is, preferably, a mass flow controller. A second system is provided in an exhaust emission analyzing system for determining a final amount of pollutants also compensated for the effects of changing water vapor content in the exhaust emissions.

Abstract: An electrode material is provided for electrochemical sensors, particularly for sensors detecting combustible gases. For these types of applications, perovskite electrode materials are known which, however, by modification of their oxygen stoichiometry, have a considerable charge carrier mobility. These defects are the causes for an additional, catalytic activity with oxidation processes at electrodes. The measurement of hydrocarbons from combustible gases is thus distorted with electrode materials of this type. These disadvantages are overcome by making such electrode materials from mixed oxides with non-perovskite crystalline structures, which have chemical compositions of one or more of the following general formulas: (A/D).sub.3-y B.sub.x C.sub.5-x O.sub.12.+-..delta., D.sub.1-y B.sub.1-x C.sub.x O.sub.4.+-..delta., D.sub.2-y B.sub.8-x C.sub.x O.sub.16.+-..delta., D.sub.2-y B.sub.1+x C.sub.1-x O.sub.5.+-..delta., or D.sub.2-y B.sub.x C.sub.2-x O.sub.7.+-..delta.

Abstract: The invention pertains to a solid-state chemical sensor with a substrate support. On one side of the support is mounted a heating element with branch circuit connections. On the other side interdigital electrodes are arranged and thereon a carbon dioxide-sensitive material, which comprises CuO and TiO.sub.3, as well as additional metal oxides, in the form of a thick film of approximately 20-200 .mu.m.

Abstract: A sensor is provided for precisely measuring the composition of mixtures of hydrogen and oxygen gas. The sensor has an active surface, at which hydrogen and oxygen are catalytically converted into water. A transport inhibiting barrier is disposed on the active surface. The heat released during the conversion is measured, and is indicative of the mixture composition.

Abstract: Embodiments of a carrier and methods of its use are disclosed. In one method, a carrier is used with a container having a positioning device to be used with a medical diagnostic analyzer having a container loading device. This method comprises releasably mating a container retaining member disposed on the carrier with the positioning device on the container. The container retaining member on the carrier is substantially aligned with the container loading device on the medical diagnostic analyzer. The container is moved from the container retaining member on the carrier to the container loading device on the medical diagnostic analyzer.

Abstract: A gas sensor for measuring a specific gas component, especially hydrocarbons, in a gas to be measured, including a hydrocarbon prevention filter preferably made of zeolite. An oxygen concentration difference between (1) an oxygen concentration in a gas to be measured from which hydrocarbons are removed by the hydrocarbon prevention filter and further combustible components are removed and (2) a known oxygen concentration or an oxygen concentration in a gas from which only combustible components are removed, is calculated. Once an oxygen amount necessary for a combustion of hydrocarbons is calculated, it is possible to measure a hydrocarbon concentration in a gas to be measured on the basis of the thus calculated oxygen amount.

Abstract: A sensor for detecting combustible gases in a test gas. The core of this sensor is comprised of a sensitive layer based on a semiconducting metal oxide that is deposited on a ceramic substrate and for which the electrical resistance provides information on the concentration of combustible gases in a test gas. The sensitive layer (3) is comprised of a compound (12) of sintered-together grains (15) of the semiconducting metal oxide, the surface of which is coated with gold and/or a gold alloy. The semiconducting metal oxide in this case is stannic oxide (SnO.sub.2), indium oxide (In.sub.2 O.sub.3), titanium oxide (TiO.sub.2) or another n-semiconducting metal oxide or metal mix oxide. The gold alloy, for example, is composed of 66 mol % gold and 33 mol % palladium (Pd).

Abstract: A hydrocarbon sensor of solid type has a pair of electrodes, and a proton conductive solid electrolyte of a barium-cerium oxide, for example, a rare earth element at least in the third element.

Abstract: A combustible gas sensor having a pair of temperature sensor sections is here disclosed. One of the pair of temperature sensor sections is covered with porous oxidizing catalytic layers (23, 24) for oxidizing a combustible gas, and the other is not covered with the oxidizing catalyst layers. In the one temperature sensor section, the combustible gas is burned, and in the other temperature sensor section, the temperature of a gas to be measured is compensated. The temperature sensor sections each comprises temperature sensitive portions (13, 14) made of a dense ceramic material, resistors (21, 22) buried therein and having a positive resistance temperature coefficient, current leads (31, 32, 41, 42) and voltage leads (33, 34, 43, 44). A method for measuring the concentration of the combustible gas by the use of this combustible gas sensor is also disclosed.

Abstract: A catalytic detector for a flammable gas comprises a substrate and a sensing structure suspended from the substrate. The sensing structure has a combined heating element and temperature sensing element in the form of a layer-deposited electrically conductive track terminating in at least two electrically conductive bridging leads. A catalytic bead is deposited over the temperature sensing element and that portion of the substrate which is directly beneath the sensing structure is etched away so as to isolate thermally the sensing structure with the temperature sensing structure being supported by the bridging leads. The electrically conductive track is sandwiched between a substrate adhesion layer for facilitating adhesion of the conductive track and a superstrate diffusion barrier layer. The invention extends to a method of manufacturing a gas detector and a sensing structure.

Abstract: A thermal gas sensing apparatus for a gas detector is provided with a gas compartment containing a gas, a gas sensor exposed to the gas in the gas compartment, and a temperature sensor exposed to the gas in the gas compartment. The gas sensing apparatus includes a circuit for generating a gas signal having a magnitude which relates to the heat capacity of the gas and a circuit for generating a temperature signal having a magnitude which relates to the temperature of the gas. The apparatus includes a circuit for supplying a variable magnitude of electrical current through the gas sensor to cause the resistance of the gas sensor to remain substantially constant. The apparatus also includes a difference amplifier for generating a gas concentration signal based upon the temperature signal and the gas signal.

Abstract: A chemical sensor couples a material that changes temperature in response to a chemical condition with an oscillator. The oscillator is coupled to the material to detect the change in temperature in the material so that the frequency of the oscillator changes in correspondence with the change in temperature as an indication of the chemical condition.

Abstract: An apparatus for measuring a combustible gas component of a subject gas in an external subject gas space, including a first processing zone communicating with the subject gas space, 58), a second processing zone communicating with the first processing zone, and a first and a second pumping cell exposed to the first and second processing zones, respectively, each cell including an oxygen ion conductive solid electrolyte layer and a pair of electrodes one of which is exposed to the first or second processing zone, wherein the first pumping cell pumps oxygen out of the first processing zone to control oxygen partial pressure in the first processing zone at a value at which the combustible gas component cannot be burned, while the second pumping cell pumps oxygen into the second processing zone to thereby burn the combustible gas component in the second processing zone, and the concentration of the combustible gas component is determined based on a current flowing or a voltage between the electrodes of the second

Abstract: A gas sensor having a sensor element which is immobilized in gas-tight fashion in a metal housing. The gas sensor has a double-walled protective tube with an outer protective sleeve and an inner protective sleeve, each of which possesses openings for the entry and/or exit of gas. The inner protective sleeve forms a gas space into which the sensor element projects with a section at the measurement-gas end. The outer protective sleeve is a sleeve having a closed enveloping surface, the openings for the entry and/or exit of gas being arranged in the cavity at the end face of the sleeve. The gas space formed by the inner protective sleeve has, perpendicular to the extension direction of the sensor element, a rectangular cross section.

Abstract: A method for preparing a test gas stream for a gas analyzer in which test gas is drawn from a test gas stream by a test gas probe, conducted through a test gas tube to a condensate separator, and then analyzed in the gas analyzer for certain components such as NO.sub.2 and SO.sub.2 for example, with the average flow rate of the test gas stream in the test gas tube being set to a value of at least 1.5 m/s.

Abstract: A device for sensing ammonia (NH.sub.3) and nitrogen oxide (NO.sub.x) gases comprising: a sensor for detecting said ammonia and said nitrogen oxide gases, said sensor including a substrate and a layer consisting of cuprate material for detection of said ammonia and said nitrogen oxide gases, wherein said layer of cuprate material is selected from the group consisting of Y:Ba:Cu:O (YBCO) and Bi:Sr:Ca:Cu:O (BSCCO); a sensor holder for supporting said sensor; a perforated cap positioned over said sensor, said perforated cap having openings for passage of said ammonia and said nitrogen oxide gases to said sensor; a detection circuit communicating with said sensor for measuring output from said sensor; and a display or recording device connected to said detection circuit for displaying or recording a concentration of said ammonia and said nitrogen oxide gases based on the output from said sensor.

Abstract: A high-temperature gas sensor for the detection of the heat tone of combustible gases includes a semiconducting ceramic layer with thermistor properties. The semiconducting ceramic layer is formed of an oxide ceramic semiconducting material having a defined crystalline structure and a thermistor characteristic of high sensitivity. A process for the manufacture of the high-temperature gas sensor includes sintering a loosely structured layer of powder particles of an oxide semiconductor with both a defined composition and high sinter activity for achieving a required high porosity of a semiconducting ceramic layer with thermistor properties.

Abstract: A nitrogen oxide detecting sensor, according to the present invention, incorporates a gas detecting portion including, as a main component thereof, an oxide compound having electric conductivity or semiconductivity, the oxide compound having a crystal structure of 2212 phase and expressed generally as: Bi.sub.2 Sr.sub.2 (Ca.sub.1-x Y.sub.x)Cu.sub.2 O.sub.8.+-..delta. where 0.6.ltoreq.x<1; 0.ltoreq..delta..ltoreq.1. Electrodes are electrically connected to the gas detecting portion. When the gas detecting portion is analyzed by X-ray diffraction using cuK.alpha. rays to obtain diffraction peak values thereof in the range of a diffraction angle between 5.degree. and 65.degree., the diffraction peak values having a sum .SIGMA. I?2212! expressed by one of the following:(a) .SIGMA. I?2212!/.SIGMA. I?T!>88.1%(b) {.SIGMA. I?2212!+.SIGMA. I?2201!}/.SIGMA. I?T!>94.8%(c) {.SIGMA. I?2212!+.SIGMA. I?Y.sub.2 O.sub.3 !} .SIGMA. I?T!>88.1%(d) {.SIGMA. I?2212!+.SIGMA. I?(Bi, Ca) O!}/.SIGMA. I?T! >88.8%where .

Abstract: A method for determining the presence of a first gas in a second gas uses a gas sensor made up of at least two pairs of electrodes, each pair of electrodes having different spacing between the electrodes. The electrodes of the gas sensor have surfaces that are reactive to the gases under investigation. The gas sensor is exposed to the gases, and the electrical resistances between the pairs of electrodes are measured over a period of time. `The results are compared with a calibration curve to determine if the first gas is present in the second, and to determine of the sensor is malfunctioning.