Abstract: A sensor array for detecting an analyte in a fluid, comprising at least first and second chemically sensitive resistors electrically connected to an electrical measuring apparatus, wherein each of the chemically sensitive resistors comprises a mixture of nonconductive material and a conductive material. Each resistor provides an electrical path through the mixture of nonconductive material and the conductive material. The resistors also provide a difference in resistance between the conductive elements when contacted with a fluid comprising an analyte at a first concentration, than when contacted with an analyte at a second different concentration. A broad range of analytes can be detected using the sensors of the present invention.

Abstract: A hydrogen sensor for the detection of hydrogen, e.g., in an environment susceptible to the incursion or generation of hydrogen. The sensor includes a rare earth metal thin film arranged for exposure to the environment and exhibiting a detectable change of physical property, e.g., optical transmissivity, electrical resistivity, magneto-resistance, and/or photoconductivity, when the rare earth metal thin film is contacted with hydrogen gas. The sensor may include an output assembly for converting the physical property change to a perceivable output. The rare earth metal thin film may correspondingly be used for signal processing applications, in which the rare earth metal thin film is contacted with hydrogen gas, and a predetermined voltage signal is selectively imposed across the rare earth metal thin film, to selectively electrically switch the film between mirror and window states, with a response being generated according to which of the mirror and window states is present.

Abstract: A method of measuring a gas concentration for measuring any one of the concentrations of NOx, NO.sub.2, NO, and O.sub.2 by using one or more sensor elements utilizing a metal oxide semiconductor as a sensing element is disclosed. In the method of measuring a gas concentration, any one of the partial pressures of NO.sub.2, NO, and O.sub.2 is calculated on the basis of the following formula (1), and any one of the concentrations of NOx, NO.sub.2, NO, and O.sub.2 is measured on the basis of the calculated partial pressure; ##EQU1## wherein R is resistance and A-H and Q are constant.

Abstract: Provided is a novel method for intelligent data acquisition in a measurement system.

Abstract: The invention relates to a method for improving the selectivity of a polymer film gas sensor. According to the method, the gas sensor is heated and a sensor parameter sensitive to the variable under measurement is recorded. According to the invention, the parameter of the sensor sensitive to the variable under measurement is measured at a plurality of instants during both the heating period and the cooling period of the sensor, a hysteresis function of the sensor response is formed over the heating and cooling periods, and on the basis of the hysteresis function, the concentration of each measured gas component is determined.

Abstract: A gas detection circuit for use in selectively detecting a predetermined gas has a plurality of gas sensors coupled to a sensor measuring circuit. Each gas sensor has a different response to the predetermined gas at a predetermined concentration. The sensor measuring circuit measures a conditioned state of each gas sensor and transmits the measurements to a cross checking circuit which determines whether the conditioned state of each gas sensor is within a corresponding window of upper and lower limit values thereby indicating the possible presence of the predetermined gas by the corresponding gas sensor. Following the testing of the conditioned state of each gas sensor, the cross checking circuit transmits a signal indicating which of the gas sensors indicates the possible presence of the predetermined gas and if all sensors are within corresponding windows, representing detection of the gas, another signal is transmitted to trigger an alarm or other warning system.

Abstract: A method and apparatus for rapidly and continuously restoring the sensing capacity of thin film sensing elements includes passing a sufficient electrical current through the sensing element to remove from the element selected components from a fluid sample in contact with the sensing element that have an affinity for and are adsorbed and accumulated onto the surface of the sensing element. The passing of current through the sensing element can be accomplished either by applying a constant voltage across the sensing element or by forcing a constant current through the sensing element. The restoration technique removes the components from the sensing element by a combination of resistive heating of the element and electron bombardment of the components on the surface of the element.

Abstract: A fluid-filled pipe is investigated by a non-intrusive procedure to determine whether the fluid is liquid or gaseous, whether it is flowing or static, the direction of flow if it is flowing, the approximate pressure if it is a gas, and the rate of flow if it is a gas. The results are obtained by applying a heater to the surface of the pipeline and measuring the upstream and downstream temperatures of the surface of the pipe wall before and after the beginning of the application of heat. Some of the data generated is compared with data from another source to assist in the determination of the characteristics to be ascertained.

Abstract: A fuel dispensing installation that includes first and second fuel tanks containing first and second fuels of different octane levels. The tanks are provided with first and second octane level sensors mounted in the first and second fuel tanks respectively for measuring fuel octane levels and generating output signals indicative of the octane levels of the first and second fuels. Conduits from the first and second tanks transport the fuel to one or more fuel dispensers. The fuel dispensers include a blending system for blending the first and second fuels to form at least one blended fuel having an intermediate octane. A site controller in electronic communication with the blending system receives the output signals and controls the blending system to permit the dispensing of one or more blended fuels based on the measured octane levels of the first and second fuels.

Abstract: A sensing device for protecting a sensor from environmental conditions present in a turbine is provided. The sensing device comprises a heat pipe exposed to the environmental conditions for protecting the sensor from these conditions. The sensing device further comprises a sensor located in a center channel of the heat pipe and a working fluid located in an annulus of the heat pipe to aid in regulating heat along the length of the heat pipe. In alternate embodiments, the sensing device further comprises power wires extending from a power source outside the turbine to the sensor for supplying power to the sensor, and signal wires extending from the sensor to a data acquisition system outside the turbine for transmitting readings from the sensor to the data acquisition system.

Abstract: A sensor for detection of a trace fluid component in a fluid environment, comprising: a piezoelectric crystal having a fundamental resonant frequency in response to an applied oscillating electric field; a coating on the piezoelectric crystal of a sensor material which is reactive with the trace fluid component to yield a solid interaction product of changed mass in relation to initial mass of the sensor material interacting with the trace fluid component to yield the solid interaction product; means for applying an oscillating electric field to the piezoelectric crystal which generates an output resonant frequency therefrom; means for (i) sampling the output resonant frequency of the piezoelectric crystal while the oscillating electric field is applied thereto, (ii) determining the change in resonant frequency from the fundamental resonant frequency that occurs on formation of the solid interaction product when the sensor material interacts with the trace fluid component in the fluid environment, and (iii) g

Abstract: A gas detector is disclosed which includes a CO sensor and a processor. The CO sensor senses an environmental CO concentration and provides a variable electrical output in response. The processor receives digitized samples of the sensor's electrical output and computes, with each measurement sample, a COHb level of a hypothetical person exposed to the CO concentration sensed. The computation involves determining an equilibrium COHb level for each measurement sample, which is compared with a previously computed COHb level associated with previously measured samples. The previously computed COHb level is updated based on the comparison. When the computed COHb level is above a predetermined danger threshold, the processor preferably causes an audible and visual alarm to be activated to alert any persons present. The gas detector can further include a CH.sub.4 sensor coupled to the processor for independently sensing CH.sub.4 levels such that an alarm is activated when the CH.sub.

Abstract: A gas sensor 1 has a catheter 3 to which a gas sensor body 4 and a signal guide member 5 for guiding a detection signal of the gas sensor body 4 are attached. The other end of the signal guide member 5 is connected to a connector 6. The gas sensor 1 is airtightly received in the reception body in the state where a connection terminal of the connector 6 is exposed to the outside. The reception body 2 is filled with a mixed gas containing a gas to be measured by a predetermined concentration. At the time of calibration, the connection terminal of the connector 6 is connected to a measurement amplifier while the reception body 2 is not opened and calibration is performed, and at the time of measurement, the reception body 2 is opened and the gas sensor 1 is taken out to perform ordinary measurement.

Abstract: The invention relates to a catalytic layer system on a resistive gas sensor, especially on a resistive gas sensor layer on a titanate base, with at least one first layer and a second layer lying over the first layer, where, according to the invention, the first layer exhibits a catalytically active substance whose volume percentage in the layer ranges from 20 to 80%. In addition, the first layer contains a titanate that corresponds to at least one titanate of the underlying gas sensor layer. This attribute guarantees favorable adhesion between the layers. Furthermore, an oxide mixture that contributes to the improved mechanical stability of the layer system is provided in the second layer instead of the catalytically active substance. To manufacture the catalytic layer system, the individual layers are applied to the sensor in a screen printing process, which allows for a rational method of production and the precise dosing and distribution of the individual layer components.

Abstract: A method and apparatus for rapidly measuring nitrogenase activity of a nitrogen fixing plant growing in a medium in a non-porous container, is described. Gas containing hydrogen is sampled at the surface of the medium at a rate approximately equal to the rate of hydrogen diffusion from the medium, and the sample is passed to a hydrogen sensor where it is measured and nitrogenase activity is determined therefrom.

Abstract: An NO.sub.x sensor is produced by sintering a plurality of columnar crystals of .beta.-type Nb.sub.2 O.sub.5. The average value M of aspect ratios b/a (wherein a represents a width and b represents a length) in the columnar crystals is set in a range of 2.11<M.ltoreq.5. The NO.sub.x sensor has a high sensitivity to NO.sub.x via an enhancement attained by control of crystal type and structure.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g. electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: The present invention enables siloxanes which have a detrimental effect on the quality of products during semiconductor production to be efficiently removed from silicon compound gases, and enables minute amounts of siloxanes in these gases to be accurately measured to a few ppb, thus allowing for improvements in quality control by offering silicon compound gases of high purity. Diatomaceous earth M filled into a removal column 2 is heated by heating means provided on the removal column 2, while an inert gas such as nitrogen or helium is fed from an inert gas delivery pipe 13 via a pressure regulator 5 and an entry valve 6 into the removal column 2, and is allowed to flow out through an outlet valve 8 in order to thermally activate the diatomaceous earth M. After activation, the removal column is cooled to a temperature of 60-0.degree. C.

Abstract: Disclosed is a gas sensor comprising a sensor element for measuring a predetermined gas component contained in an introduced measurement gas, and a protective cover arranged to surround a forward end of the sensor element; the gas sensor including the sensor element having a gas-introducing port which is disposed at a forward end surface thereof for introducing the measurement gas thereinto; and the protective cover comprising an inner protective cover and an outer protective cover. The inner protective cover is provided with an opening section which makes communication with the gas-introducing port. An inner protective cover space, which is formed between the inner protective cover and the sensor element, is isolated from a communication passage which makes communication from the opening section of the inner protective cover to the gas-introducing port of the sensor element so that the measurement gas principally diffuses and flows from the opening section into the gas-introducing port of the sensor element.

Abstract: A safety system (10) for a materials handling device, for example fork lift truck, conveyor, comprises a sensing head (11) linked to a pressurization control unit (12). The sensing head (11) monitors the level of explosive vapors in proximity to the device relative to low explosive level (LEL). When a level of explosive vapors of below 25% LEL are detected, the pressurization control unit (12) maintains the supply of an inert gas for a supply (13) to at least one sealed enclosure which encloses any hazardous components in the device at substantially atmospheric pressure. When a level of explosive vapors above 25% LEL is detected, the pressurization control device (12) is operable to increase the supply of inert gas to the enclosure (14) to being the pressure in the enclosure (14) to greater than atmospheric pressure.

Abstract: In a microwave resonator for continuous spectroscopic gas analysis with a microwave cavity having dimensions depending on the operating frequency and a setting for a low quality Q of its base mode and microwave reflectors disposed at its opposite ends and including a round hollow conductor part and a co-axial conductor part separated by a pressure-tight dielectric window, an internal conductor part is axially movably supported in the coaxial conductor part by the microwave reflector at one end of the co-axial conductor part, the other reflector being axially movable for tuning the resonator to a maximal absorption frequency and a by-pass line extends past the co-axial conductor part in the area of the dielectric window and has a short branch connected to the co-axial conductor part and including a restrictor for supplying only a relatively small flow of gas from the bypass line to the conductor part of the microwave resonator.

Abstract: A codable gas detection system with at least one interchangeable gas sensor (2), which has standardized plug-type connections (5,6) between the gas sensor (2) and the measuring device (1), but is also able to prevent measured values of an unauthorized gas sensor (2) from being processed. Each gas sensor (2) contains a memory (3) with gas sensor-specific data and is connected via a line to the measuring device (1) with a first calculating and evaluating unit (7), to a downstream memory (8) and preferably to an alarm device (10). Via the second plug-type connection (5), the sensor element (4) proper is connected to a contacting unit (9) in the measuring device (1), and the contacting unit (9) is connected to the first calculating and evaluating unit (7), on the one hand, and to a downstream, second calculating and evaluating unit (11) for the measured value evaluation proper, on the other hand.

Abstract: A sensor system and method for measuring very low levels of a particular gas in an atmosphere which initially has high level of the gas. A pair of sensors of the particular gas are provided, one of which senses high levels of the particular gas and the other of which senses very low levels. The sensor which senses very low levels of the gas is not exposed to the atmosphere until the gas level has reached a low level, thereby enabling it to more quickly respond to further reduction in the gas.

Abstract: A process for avoiding error in determining the gas consumption of a sample located in a closed container. An automatic avoidance of error during the phase of adaptation of the sample to the temperature level in an incubator is achieved by monitoring the container pressure before the beginning of measurement in a test phase, and the measurement values for the measurement of the gas consumption are to be evaluated from the reference time point at which the pressure variation over time in the container lies within a predetermined value range.

Abstract: A method and apparatus are disclosed for the near simultaneous detection of light emitted from ozone induced chemiluminescence of nitrogen and sulfur species capable of undergoing ozone induced chemiluminescence in a single instrument. A sample containing sulfur and/or nitrogen is first subjected to an oxidative/reductive process which generates ozone reactive nitrogen and sulfur species which are then forwarded to an specially designed ozone/detector chamber. The ozone reactive species are brought in contact with ozone in the special chamber and the chemiluminescence of the nitrogen species and the sulfur species are measured and quantitated.

Abstract: A combustible gas detector or sensors having a multi-level sensitivity circuitry. The gas detector has a bridge circuit for outputing voltages indicative of gas concentrations contacting the bridge circuit. There is a power supply node electrically coupled to one end of the bridge circuit. There is also a voltage control circuit, coupled between the bridge circuit and the power supply node, for controlling when at least a low and high input voltage level is supplied to the bridge circuit so that the bridge circuit has at least two levels of gas concentration discernability. The bridge circuit outputs distinguishable voltage levels for high gas concentrations in response to receiving the low voltage level. Additionally, the bridge circuit outputs distinguishable voltage levels for low gas concentrations in response to receiving the high voltage level.

Abstract: A portal apparatus for screening objects or persons for the presence of trace amounts of chemical substances such as illicit drugs or explosives. The apparatus has a test space, in which a person may stand, defined by two generally upright sides spanned by a horizontal transom. One or more fans in the transom generate a downward air flow (uni-directional) within the test space. The air flows downwardly from a high pressure upper zone, past the object or person to be screened. Air moving past the object dislodges from the surface thereof both volatile and nonvolatile particles of the target substance. The particles are entrained into the air flow which continues flowing downward to a lower zone of reduced pressure, where the particle-bearing air stream is directed out of the test space and toward preconcentrator and detection components. The sides of the portal are specially configured to partially contain and maintain the air flow.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: A system for controlling pressure flow and concentration Of O.sub.3 /O.sub.2 positions a thermal MFC upstream from an ozone generator to avoid the adverse effects of ozone on the thermal MFC. A flow restrictor diverts a precise amount of flow to an ozone monitor so that the flow to a CVD chamber is precisely controlled. In other embodiments a full-flow ozone monitor and non-thermal MFC are utilized.

Abstract: Methods for measuring the surface area of a top region of a silicon wafer by initially depositing a monolayer of hexamethyldisilizane over the surface area of the silicon wafer. The silicon wafer is then positioned within a vacuum environment. Next, oxygen is introduced into the vacuum chamber so that the HMDS substantially reacts with the oxygen to form products such as carbon dioxide and water. At least one of the water and the carbon dioxide are measured from the known volume of the vacuum chamber. Based on the amount of product formed, the amount of HMDS covering the surface area is determined. Finally, from the amount of HMDS calculated to be originally positioned on the surface area, a value for the surface area is determined.

Abstract: A method of operating chemical sensors (21) uses synchronously pulsed signals to reduce the power consumption of the chemical sensors (21). A first voltage source can be used to control and to heat multiple heating elements of the chemical sensors (21). The first voltage source can also be used to control other sensors which do not require elevated temperature operation. A second voltage source can be used to operate and bias the chemical sensors (21) heated by the multiple heating elements. Power consumption is reduced by turning or pulsing off the heating element (16) when it is not used.

Abstract: A test pack for evaluating an ethylene oxide sterilization process, comprising an open ended fiber board tubular member, an end cap enclosing each end of said tubular member, said end caps defining a test chamber within the tubular member, one of said end caps having an opening to permit the egress of ethylene oxide into the test chamber. A fiber ball is inserted into the test chamber at a location remote from the end cap having the opening therein, and a chemical type sterilization indicator is placed within the test chamber.

Abstract: A standard gas introduction passage and an air inlet port are provided on positions downstream and upstream a dehumidifier respectively. A zero gas and a span gas are measured in dry states, a value of the atmosphere introduced from the air inlet port which is measured in the same moisture concentration as the sample gas is subtracted as a moisture interference value from the measured value of the sample gas for correcting moisture interference, and calibration curve data are applied to a result of measurement after the correction. Calibration can be finished in a short period, whereby the capacities of standard gas cylinders can be reduced and the overall device can be miniaturized.

Abstract: An apparatus for the recognition of exchangeable parts in an analytical measuring instrument or in an analytical measurement system with several analytical devices, which contain exchangeable parts has identification modules each attached to an exchangeable part, and transmit-receive devices which can receive information signals from an identification module and send information signals to an identification module, and a control device which evaluates the information from an identification module. The control device can cause a message to be displayed on a display device, if the information read out from an identification module does not fulfill certain conditions, for example with regard to the quality of the corresponding part.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g. electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: Apparatus and a method for detecting the presence of a predetermined target gas (e.g. CO) is disclosed. The gas has a predetermined pattern of peaks of absorbance to radiation lying within a particular radiation range (e.g. infrared), the absorbance peaks alternating with gaps in which the gas transmits the radiation. A source (12) passes IR radiation through a comb filter (5) and a measurement cell (22) containing the target gas. The comb filter (5) has successive passbands separated by absorbance gaps. The passbands of the comb filter are repeatedly shifted relative to the IR radiation between a correlation position in which they coincide with at least some of the absorbance peaks of the target gas and an anti-correlation position in which the passbands coincide with at least some of the absorbance gaps of the gas.

Abstract: A gas detection system and method selectively detects a gas in the presence of nonselected contaminant gases. The system includes a housing having a collection chamber and a sampling chamber containing a variable resister and a molecular sieve. A molecular sieve is positioned between the chambers for selectively passing a target gas from the collection chamber to the sampling chamber. An organic molecular sieve permits only selected low molecular weight gases, such as ammonia and carbon monoxide to come into contact with the sensor.

Abstract: A method for determining the concentration of a substance in a gaseous medium using a chemical sensor is disclosed. To ensure that the concentration is within the nominal measuring range of the sensor, the sample gas stream is mixed with a diluting gas stream in a mixing device to form a measured gas stream. This mixing process involves setting an adjustable dilution ratio and alternately supplying the sample gas stream and diluting gas stream to the mixing device. By adjusting the amount of time each gas is supplied to the mixing device the dilution ration can be varied to thereby maintain the concentration of the substance detected by chemical sensor within the nominal measuring range of the sensor. Calculation of the concentration of the substance is thus simplified since the dilution ration is automatically a known quantity since the sample gas stream and diluting gas stream are supplied cyclically alternately and in succession with a definite volume flow to measuring device.

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 and a detector for detecting nitrogen oxide in test gas are provided wherein test gas which contains NOx and interference gases is supplied through an oxygen feeder 4 into a measuring chamber 1a, and the interference gases are oxidized by oxygen or oxygen ion supplied to the measuring chamber 1a through oxygen feeder 4. A total amount of NOx in the test gas is detected based on a level of EMF produced between a first electrode 2 for detecting oxygen and NO2 gas and a second electrode 3 for detecting oxygen.

Abstract: A method and device for the detection of vapors of cocaine and associated compounds are disclosed. The method involves sampling a volume of air suspected of containing cocaine vapors, passing this air through a filtration system that removes any particulate matter and binds vapors of cocaine and associated compounds, if present, for further analysis. A preferred associated compound-vapor is that of ecgonidine methyl ester (EDME), and a marker for the presence of cocaine. The device is comprised of a sampling, filtration and vacuum port components and can be easily attached to a container, and suction source, for the sampling of air.

Abstract: An air fuel ratio sensor has a sensor element having a sensing portion and a flange portion in contact with a tapered portion of an accommodation hole of a housing. The sensor element is hot crimped at a hot crimping portion of a housing. At least the hot crimping portion is made of a ferritic stainless steel formed by cold forging and having a composition content comprising a total amount of C and N impurities of 0.03 wt % or below. The average hot crimping temperature of the housing is performed at lower than 1000.degree. C. as applied for a time period of one second or less.

Abstract: An electrochemical gas sensor is provided, the use of which permits quantitative measurement of volatile gas contaminants in an atmosphere being monitored, generally at ambient temperatures below 100.degree. C. The sensor is constructed of a sensor electrode and a reference electrode on a separator in such a manner as to be exposed to the atmosphere which is sensed for gaseous contaminants. In an alternative embodiment, the sensors can be covered with a selective filter which will selectively allow only small molecule toxic gases to pass for sensing by the sensor electrode while excluding larger interfering gas molecules. In another alternative embodiment, a multiple layer electrochemical gas sensor detects the presence of volatile gas contaminants in a sample gas as well as humidity, temperature, and/or pressure of the gas sample.

Abstract: A system and method for recovering a gasoline vapor/air mixture from a vehicle tank during the dispensing of gasoline from a storage tank into the vehicle tank in which the flow of the mixture from the vehicle tank to the storage tank is induced during the dispensing of the gasoline. The amount of oxygen in the mixture is sensed and the flow of the mixture is shut off when the oxygen content in the mixture attains a predetermined value.

Abstract: A process and apparatus for determining the amount of contamination in the lubricant phase of a refrigeration system. The process utilizes a clear glass tube which contains an inert substance such as glass beads coated with a solvatochromic compound, preferably the solvatochromic compound is a mixture of Benzophenoxazine and Benzophenoxazone. A sample of the lubricant to be tested is passed into the glass tube and passes over the glass beads, picking up a portion of the solvatochromic compound. A white absorbent material such as sterile cellulose is positioned adjacent the coated substrate and the color reaction between the lubricant and the solvatochromic compound is clearly evident on the white absorbent material which then can be compared with a standard set of colors to determine the amount of the contamination.

Abstract: A combustible gas detector or sensor having catalytic coated resistance sensing elements that uses a wheatstone bridge to sense the presence and concentration of any combustible gases in a gas stream that chemically react with such catalytic coatings. Wherein there is a power supply node electrically coupling one end of a first and second bridge of the wheatstone bridge. There is a ground node electrically coupling the first and second bridge at another end. There is a first and second metered node located on the first and second bridge respectively. There is a first catalytic sensor element, located on the first bridge between the power node and first metered node. There is a second catalytic sensor element, located on the second bridge between the ground node and second metered node. There is a first reference sensor element, located on the first bridge and in series with the first catalytic sensor element, and coupled between the first metered node and the ground node.

Abstract: A method of introducing selectivity to a non-selective gas sensor for determining an amount of a gas of interest contained in a measurement gas wherein the non-selective gas sensor responds not only to the gas of interest but also to other interfering gases contained in the measurement gas, the method includes the steps of periodically modulating a specified flux of a measurement gas at a first predetermined frequency, periodically modulating a specified flux of a gas of interest at a second predetermined frequency, adding the modulated flux of the gas of interest to the modulated flux of the measurement gas, exposing a non-selective gas sensor to the combination of the modulated flux of the measurement gas and the modulated flux of the gas of interest, measuring a sensor output of the non-selective gas sensor at zero frequency (DC) and at specified frequencies (AC), and determining an original concentration of the gas of interest in the measurement gas from the measured sensor output at zero frequency and at

Abstract: A method for determining an amount of a gas of interest contained in a measurement gas includes the steps of periodically modulating a specified flux of a measurement gas at a first predetermined frequency, periodically modulating a specified flux of a specified gas that can react non-linearly with the gas of interest at a second predetermined frequency, adding the modulated flux of the specified gas to the modulated flux of the measurement gas, passing the mixture of the two modulated gas fluxes through a reactor where the gas of interest reacts with the specified gas to produce a third gas, exposing a gas sensor that can respond to the third gas present in the gas mixture after the reactor, measuring the sensor output at zero frequency (DC) and at specified frequencies (AC), and determining the original concentration of the gas of interest in the measurement gas from the measured sensor output at zero frequency and at the specified frequencies.

Abstract: A substrate carrying a first electrode and a second electrode, the first and second electrodes being disposed adjacent to one another, the first electrode being disposed between the substrate and a gas-sensitive component, the gas sensitive component comprising an n-type semiconductor, the gas-sensitive component having a resistance that is gas-dependent and temperature-dependent, and the second electrode being disposed between the substrate and a non-gas-sensitive component, the non-gas-sensitive component comprising a n-type semiconductor and a p-type semiconductor, the non-gas-sensitive component having a resistance that is temperature-dependent and that is not gas-dependent and wherein the n-type semiconductor of the non-gas-sensitive component is Ga.sub.2 O.sub.3 and the p-type semiconductor of the non-gas-sensitive component is ZrO.sub.2.

Abstract: A differential refractometer measures the difference of refractive index of electromagnetic centimeter waves of samples of gas with high sensitivity, and can be used to measure the gradient of refractive index of electromagnetic waves in air, and more particularly, to measure radar ducting conditions low over bodies of water. The instrument uses two microwave oscillators, each with its own frequency controlling cavity, with the frequencies of the oscillators differing by a specific value. Air from each of two intakes, vertically separated a specific distance, is directed into each cavity, and the difference frequency measured for a short time, to provide a first measured difference frequency. Then, the air flow from the intakes are cross-fed to the cavities, and the difference frequency is measured for a short time to provide a second measured difference frequency.