Abstract: A failure diagnostic apparatus for a gas concentration detecting apparatus is provided, which can early detect disconnection in a cell included in the gas concentration detecting apparatus. The gas concentration detecting apparatus is provided, which includes cells each of which pumps out oxygen in a gas detection chamber, thereby generating an electric current corresponding to the concentration of oxygen in the gas detection chamber. A heater which heats each of the cells to an activation temperature is provided. A period during which a predetermined electric current should flow in the cell after the heater starts heating is detected. A determination on whether there is disconnection is made based on whether each of electric currents flowing in the cells is appropriate.

Abstract: Provided is an inspection method for a multilayer gas sensing device, capable of certainly and easily detecting a defective product originating from faults such as gaps or cracks. For the inspection of the gas sensing device including a sensor cell in which a measured gas side electrode is coated with a porous diffusion resistance layer in a stacked condition and the diffusion resistance layer is further coated with a dense protective layer in a stacked condition, in a state where the gas sensing device is immersed in a conductive inspection solution and a reference electrode of the sensor cell is placed into a non-contact with the solution, a voltage is applied between the solution and the reference electrode to measure a current flowing therebetween. On the basis of the measured current value, a decision is made as to whether or not the insulation is kept between the solution and the reference electrode.

Abstract: A vehicle exhaust measurement system is provided includes that a conduit having a conduit inlet and a conduit outlet. A make-up air tube is connected to and is in fluid communication with the conduit inlet. The make-up air tube provides make-up air for mixing an exhaust gas. A mixed gas tube is connected to and is in fluid communication with the conduit outlet. The mixed gas tube conveys a mixture of make-up air and exhaust gas to analysis equipment. In the preferred embodiment, the exhaust gas tube extends through an outer wall of the conduit. A mixing plate is arranged in either the conduit or the mixed gas tube with the exhaust gas tube extending to a position adjacent to the mixing plate. The exhaust gas tube conveys the exhaust gas to the mixing plate to mix the exhaust gas and the make-up air at the mixing plate.

Abstract: An intake air oxygen concentration sensor calibration device is provided with an oxygen concentration sensor that detects a concentration of oxygen contained in intake air, intake passageway pressure detection means, stable condition determination means that determines whether the intake passageway pressure is in a stable condition based on the amplitude of fluctuations in intake passageway pressure and a predetermined stable condition criterion value, calibration coefficient calculation means that calculates a calibration coefficient based on the intake passageway pressure and a reference output value of the oxygen concentration sensor, and calibration means that calibrates the output of the oxygen concentration sensor based on the calibration coefficient, wherein and the stable condition criterion value is set so that the smaller the intake passageway pressure detected, the smaller the value, and the greater the intake passageway pressure detected, the greater the value, and the calibration coefficient calc

Abstract: A gas component analysis system transmits, reflects, and detects light using infrared light source; a reflector unit; and a light detector. The light is transmitted through a gas, such as air containing vehicle emissions, reflected, and detected for analysis and measurement of the amount of absorption that has occurred at known wavelengths. The amount of absorption may be used to determine concentrations of reference gases corresponding to specific wavelengths.

Abstract: A method and apparatus for calibrating a sensor for determination of the concentration of a sterilant, e.g., hydrogen peroxide vapor, in a sterilization system. This invention provides a method for calibrating a sensor that is used for measuring the quantity of a sterilant in a system for delivering the sterilant, the method comprising the steps of: (a) generating reference calibration data, the reference calibration data showing a mathematical relationship between a measurable parameter, e.g. voltage, and a quantity of the sterilant, e.g.

Abstract: A method in calibrating or checking an apparatus for determining in a person's exhalation air the concentration of a specific substance is disclosed. The apparatus comprises means for passing exhalation air along a free measuring length, and means for supplying air of a predetermined composition to the measuring length to produce an air flow along the length. A mixture of the substance and water in a specified concentration thereof inder instantaneous evaporation is injected into the air when supplied to the measuring length. The concentration of the substance and the concentration of water vapor in the air flow along the measuring length is determined. The substance gas flow and the water vapor flow are calculated, and the ratio thereof is compared with the specified concentration of the mixture.

Abstract: An element impedance detection apparatus for an oxygen sensor is provided with a first switching device, a second resistor, first resistor, and a first condenser for application of a sweep voltage to the oxygen sensor. The first switching device is switched to ON and the sweep voltage applied; a sensor current I that flows in the oxygen sensor along with application of the sweep voltage is then detected. Element impedance is calculated based on the sweep voltage and the sensor current. The second resistor, the first resistor and the first condenser are connected to the oxygen sensor such that a time constant of the sweep voltage increases as the element impedance becomes larger.

Abstract: A constant flow of air through a personal air sampler is provided regardless of changes in the air flow path, by altering the pump speed as a function of the power taken by the pump. The characteristics of the pump are precalibrated to provide a constant used together with the square of the voltage appearing across the motor armature coils (applied voltage minus back Emf), which reflects the power currently used, to adjust the motor speed and thus provide a constant flow of air under changing conditions of resistance.

Abstract: Disclosed is a gas sensor for controlling a concentration of oxygen and/or measuring NOx by allowing a current to flow through an ion-conductive member for conducting oxygen ion, by the aid of a current supply circuit, wherein the current, which is outputted from the current supply circuit, has a pulse waveform (current signal) having a constant crest value, and the current supply circuit comprises a rectangular wave-generating circuit for controlling a frequency of the current signal on the basis of an electromotive force generated in the ion-conductive member to which the current signal is supplied. Accordingly, it is possible to highly accurately measure the predetermined gas component while scarcely being affected by the electric noise or the like.

Abstract: A sensor element for limit current probes for determining the &lgr; value of gas mixtures and a method of calibrating such sensor elements. The sensor element has an internal and an external pump electrode arranged on a ceramic body, the internal pump electrode being arranged in a diffusion channel delimited by a diffusion barrier, and a gas intake orifice running through the ceramic substrate and the diffusion channel in a direction that is essentially perpendicular to the surface of the ceramic substrate. The diffusion resistance of the diffusion barrier can be adjusted essentially linearly by selectively changing the diameter of the gas intake orifice. Calibration is performed by selecting at least one sensor element of a production lot, whose pump voltage is, measured at a selected pump current, from which the optimum diameter of the gas intake orifice can be calculated from the deviations from the ideal values using a simple ratio.

Abstract: The design and manufacturing processes for Hollow Cathode Assemblies (HCA's) that operate over a broad range of emission currents up to 30 Amperes, at low potentials, with lifetimes in excess of 17,500 hours. The processes include contamination control procedures which cover hollow cathode component cleaning procedures, gas feed system designs and specifications, and hollow cathode activation and operating procedures to thereby produce cathode assemblies that have demonstrated stable and repeatable operating conditions, for both the discharge current and voltage. The HCA of this invention provides lifetimes of greater than 10,000 hours, and expected lifetimes of greater than 17,500 hours, whereas the present state-of-the-art is less than 500 hours at emission currents in excess of 1 Ampere.

Abstract: An apparatus is described for calibrating at least one sensor within a gas detector (22), which detector has a gas inlet in fluid communication with the or each sensor, the apparatus comprising a housing (10) that contains: a) a surface (24) for abutting against the detector (22); b) a holder (14) for holding the gas detector (22) with respect to the housing (10) in such a manner that a region of the detector containing the gas inlet abuts against the surface (24) of the housing to form a sealed gas interface between the surface (24) and the detector (22); c) a connector for connecting a source of pressurised calibration gas (12) to the apparatus, d) a conduit (32) for delivering a calibration gas from the connector (34) to the interface between the detector and the apparatus housing, e) electrical connections (40) within the holder for forming electrical connections between the apparatus and a detector held within the holder, and e) a flow controller (34, 36) within the conduit for providing calibration gas

Abstract: A chemical adsorption system and method comprising an apparatus containing a solid adsorption article comprising a known amount of a chemical adsorbate material disposed on a solid adsorbent material. Trace amounts of the adsorbate are released from the adsorbent using an inert gas. By controlling various parameters such as the temperature of the adsorption article, the amount of the adsorbate on the adsorbent, and the flow rate of inert gas through the apparatus, the amount of chemical adsorbate material vapor that is released from the adsorbent can be precisely controlled and predicted. The apparatus contains no liquid chemical materials, and serves as both an internal chemical reference standard to the attached chemical vapor monitor and as a chemical surface passivator. Furthermore, the invention is capable of spanning several orders of magnitude in chemical vapor concentration from the parts-per-million (ppm) to parts-per-trillion (ppt) range.

Abstract: An oxygen sensor includes a detector to be positioned between the ambient air and the exhaust gas, which generates a voltage corresponding to a difference in oxygen partial pressure therebetween. A controller performs monitoring of the output voltage from the oxygen sensor and determines an occurrence of fracture in the detector when detecting the generation of a lean signal, which is a signal indicating the above-described difference in the oxygen partial pressure is small, being frequently more than a certain value, and carries out an abnormality diagnosis to the oxygen sensor.

Abstract: The present invention is directed to a carbon monoxide detector tester and method for using the carbon monoxide detector tester to determine the operability of a carbon monoxide detector. The tester comprises a closable box adapted to receive and house a carbon monoxide detector and a carbon monoxide emitting material. In use, the closable box is opened and the carbon monoxide detector and carbon monoxide emitting material are inserted within. The carbon monoxide emitting material is ignited and the box is closed. A properly functioning carbon monoxide detector will then sound an alarm indicating a properly functioning detector whereas an improperly functioning detector will not sound an alarm, thus indicating a not properly functioning detector.

Abstract: An intake air oxygen concentration sensor calibration device is provided with an oxygen concentration sensor that detects a concentration of oxygen contained in intake air, intake passageway pressure detection means, stable condition determination means that determines whether the intake passageway pressure is in a stable condition based on the amplitude of fluctuations in intake passageway pressure and a predetermined stable condition criterion value, calibration coefficient calculation means that calculates a calibration coefficient based on the intake passageway pressure and a reference output value of the oxygen concentration sensor, and calibration means that calibrates the output of the oxygen concentration sensor based on the calibration coefficient, wherein and the stable condition criterion value is set so that the smaller the intake passageway pressure detected, the smaller the value, and the greater the intake passageway pressure detected, the greater the value, and the calibration coefficient calc

Abstract: It is difficult to test gas detectors that are difficult to access. The test device according to the invention is functionally linked with the gas detector or with the heat detector and substantially simplifies testing of such detectors.

Abstract: In detecting a deterioration of an air-fuel ratio sensor, a sensor output change speed integrated value is calculated when an element temperature of a solid electrolyte is stabilized at a low temperature. Successively, a sensor output change speed integrated value is calculated when the solid electrolyte element is stabilized at a high temperature. Finally, a deviation between the change speed integrated values is calculated. By comparing the deviation amount with a predetermined determinant, presence or absence of the deterioration is determined.

Abstract: A calibration adaptor for a gas sensing device having a gas entry port therein includes a base piece having a gas entry port therein which is fixedly attached to a surface of the gas sensing device, and provided with means for releasably retaining the base piece in a first position in which the gas entry port of the gas sensing device is open to detect ambient gases, and means for moving the attached base piece to a second position in which the gas entry port of the base piece is aligned with the gas entry port of the gas sensing device, and controls entry of gas into the gas entry port of the gas sensing device. A calibration gas source may be attached to the gas entry port of the base piece.

Abstract: The device comprises a voltage divider (Rv1, Rv2) to whose two terminals the oscillator signal with a phase position that is mutually opposed is supplied until, in the instance of a switched-on probe heating, the voltage (VRpvs) that is proportional to the probe internal resistance (Rpvs) falls below a predetermined set value (set), whereby, at this point in time, the output signal of the oscillator (SZ) is supplied to both terminals of the voltage divider (Rv1, Rv2) with the same phase position (area 1) thus effecting an amplitude change-over (amplitude amplification).

Abstract: An instrument provides a quantitative measurement of an analyte in a gas. It includes a detection cell that provides an indication of an amount of analyte present in the gas, and a valve having a closed position, a sample gas position, and a calibration gas position. There is a calibration gas inlet orifice in communication with a gas outlet through a first flow path including the valve and the detection cell, and a sample gas inlet orifice in communication with the gas outlet through a second flow path including a scrubber, the valve, and the detection cell. Two orifices of different sizes, a sample gas orifice along the second flow path, and a bypass orifice positioned between the sample gas orifice and the gas outlet, prevent a build up of excessive pressure in the instrument when the valve is in the closed position or the calibration gas position.

Abstract: A method and apparatus is disclosed which employs a pulse-controlled microdroplet fluid delivery system for precisely dispensing fragrances and other odor producing vapors. The pulse-controlled fluid delivery device is capable of ejecting microdroplets of fluid with a diameter less than 350 micrometers at a controlled ejection rate based upon inkjet printing technology. The pulse-controlled fluid delivery system includes mechanisms for vaporizing the fluids and delivery of the vapors to the nose, which is controlled by a programmable system controller capable of real time data-driven dispensing with a multi-fluid capability. Synthesis of custom fragrances is made possible by a multijet programmed control system which adjusts dispensing rates of components. Calibration of a prior art “electronic nose” is disclosed. A precise calibration gas is produced in real-time to counteract the effect of drifting.

Abstract: The mass of particulate matter in a particle laden gas stream is measured using a single mass detector. The particle laden gas stream and a substantially identical but particle-free gas stream alternately engage the mass detector during successive measurement time periods. A difference between a reading provided by the mass detector for a current measurement time period and a reading provided by the mass detector for a consecutive measurement time period is determined. This difference intrinsically corrects for volatilization losses occurring during the current measurement time period. A measure of the mass or concentration of particulate matter in the particulate laden gas is determined from this difference.

Abstract: An impactor assembly comprises a base for supporting a plurality of cups that form impactor plates, and a nozzle above each of the cups through which a flow passes for classification. The cover is removable, and a test cover can be put into position for mounting in place and providing outlets connectable to pressure sensor for determining pressure drop across the nozzle plates at each impactor stage. The cover also is designed to be easily washed by having no blind cavities or moving parts on the cover, and the latch and other hinge assemblies are all supported on the base. The flow enters and exits the impactor without having external connections on the cover.

Abstract: An intake air oxygen concentration sensor calibration device is provided with an oxygen concentration sensor that detects a concentration of oxygen contained in intake air, intake passageway pressure detection means, stable condition determination means that determines whether the intake passageway pressure is in a stable condition based on the amplitude of fluctuations in intake passageway pressure and a predetermined stable condition criterion value, calibration coefficient calculation means that calculates a calibration coefficient based on the intake passageway pressure and a reference output value of the oxygen concentration sensor, and calibration means that calibrates the output of the oxygen concentration sensor based on the calibration coefficient, wherein and the stable condition criterion value is set so that the smaller the intake passageway pressure detected, the smaller the value, and the greater the intake passageway pressure detected, the greater the value, and the calibration coefficient calc

Abstract: A method for testing gas detection instruments includes providing at least two reagents, immobilizing at least one of the reagents into a matrix material, heating the matrix material until the matrix permits movement of the reagent and generating a gas responsive to chemical reaction between the reagents. The gas is introduced into the sensor portion of the gas detection instrument to test the same. The reagents may each be immobilized on the matrix material with the heating serving to soften or melt the matrix material to permit chemical interaction. In a preferred embodiment, the heating is effected at about 90 to 150° C. The method may be employed to generate carbon monoxide or other gases of interest. Corresponding apparatus is provided. The apparatus may be structured to be inserted into or receive the gas detection instrument or have its output in communication therewith.

Abstract: A method and apparatus for diagnosing defects in electrochemical gas sensors, in which the water vapor pressure of the air surrounding a sensor is suddenly changed by changing to more dry or more humid air, thereby causing a sharp change in the acidity at the working electrode, and hence, a transient current from the sensor. The response of the sensor to the change in water vapor pressure is monitored and is used for sensor diagnostics. Lack of sensitivity of the sensor to the water vapor pressure change is an indication that the sensor does not have appropriate sensitivity to the gas to be detected. The method and apparatus are particularly useful for diagnostic testing of sensors without a gas filter.

Abstract: The present invention provides a method of calibrating sensors within a gas detector (36) having a housing containing a gas inlet whereby gas can diffuse from the inlet to the sensors. The gas inlet in the housing is held against part (34) of the calibration apparatus to form a sealed gas interface between the apparatus and the detector; a source (10) of pressurised calibration gas is connected to the apparatus, and a predetermined dose of calibration gas is delivered to the interface between the detector (36) and the calibration apparatus (34) at a predetermined pressure. The source (10) of pressurised calibration gas may contain single or multiple calibration doses and, if the former, the calibration apparatus includes a dosing system such as cylinder (14) for metering individual doses of calibration gas.

Abstract: A calibration adaptor for a gas sensing device having a gas entry port therein includes a base piece having a gas entry port therein which is fixedly attached to a surface of the gas sensing device, and provided with means for releasably retaining the base piece in a first position in which the gas entry port of the gas sensing device is open to detect ambient gases, and means for moving the attached base piece to a second position in which the gas entry port of the base piece is aligned with the gas entry port of the gas sensing device, and controls entry of gas into the gas entry port of the gas sensing device. A calibration gas source may be attached to the gas entry port of the base piece.

Abstract: The self-calibrating carbon monoxide detector and method of the present invention utilize the gas for which the detector was designed to detect as the calibration gas. Specifically, a carbon monoxide gas generator is included in the detector assembly, and is controlled to produce a known amount of CO. The sensor response to the quantity of CO generated is monitored, and the calibration thereof adjusted as necessary. The operation of the gas generator is also monitored, and any failures are flagged for user attention. The gas generator specifically suppresses the generation of hydrogen through the materials used in its construction. Temperature effects may also be compensated either through control of the gas generation control parameters or compensation of the sensor output in view of the generator temperature effects.

Abstract: A test leak unit (1) includes a supply of test gas, preferably helium, and an element (14) for determining leakage rates. The aim of the invention is to create a simple, robust and easily refilled test leak unit, especially for detecting packaging leaks. To this end, the test gas supply is stored under substantially atmospheric pressure in a resealable reservoir (2) including a closing part (3), such that when the reservoir (2) is closed, a test gas-impermeable seal is developed between the closing part (3) and the reservoir (2), and the leakage rate-determining element (14) forms part of the closing part (3).

Abstract: To balance ozone sensors for the onboard diagnosis of a catalytic element which is arranged in a vehicle and is exposed to an ambient airstream, for breaking down ozone, predetermined enable conditions allowing the sensor balancing to be carried out are checked, and if the enable conditions are fulfilled the values of the output signals from the ozone sensors are recorded and compared with one another. This comparison gives a deviation value which is characteristic of the deviation between the two values, and the deviation value is used to decide whether sensor balancing is required and indeed possible. If sensor balancing is required and possible, the values of the output signals from the ozone sensors are compared with a threshold value and depending on the result of this comparison either an additive or a multiplicative correction of the values of the output signals is performed.

Abstract: An automatic calibration mode for a carbon dioxide sensor is based on using a zero gas. The sensor is designed to recognize a distinctive rate of change pattern of carbon dioxide concentrations that would be indicative of a zero calibration routine. This approach can be used for other infrared sensors.

Abstract: A method and system relating to an improvement in measuring accuracy of a gas concentration sensor, the method comprising the steps of measuring a parameter of the sensor, the parameter being a resistance or a capacitance, that is sensitive to the gas or its concentration being measured, and simultaneously changing the temperature of the sensor in a cyclic manner. The parameter of the sensor being measured is measured more than two times or continuously during each heating cycle. The measured parameter value is filtered to obtain a signal component associated with the fundamental frequency of the heating cycle for use at a later step, and the thus filtered signal component is used in the correction and/or calibration of actual output signal of the sensor.

Abstract: Before starting an air-fuel ratio feedback control utilizing an air-fuel ratio sensor, activation of a wide-range air-fuel ratio sensor in an internal combustion engine is diagnosed by calculating heat transferred to and from the air-fuel ratio sensor, the output value of the wide-range air-fuel ratio sensor varies in response to oxygen concentration in exhaust which varies according to the air-fuel ratio of an intake air-fuel mixture of the internal combustion engine. The activation time from the starting of the engine until the air-fuel ratio sensor is activated is estimate based on the calculated result of the heat transfer. Alternatively, activation of the sensor is diagnosed under the condition that an output voltage of the oxygen concentration detecting unit of the sensor is fixed to a value either equal to or above a rich-side set voltage or equal to or under a lean-side set voltage, before starting the air-fuel ratio feedback control.

Abstract: This invention provides a method for monitoring the function and/or regeneration of a gas probe. The invention includes a measurement of first and second pump currents of the gas probe and a determination of a difference between the first and second pump currents (&Dgr;I). If &Dgr;I exceeds a pregiven value, then a saturation pump voltage is applied and the difference between a resulting pump current and a previously stored minimum pump current (&Dgr;I plus) is determined. If &Dgr;I plus exceeds a pregiven value, then a regeneration voltage is applied.

Abstract: A method of self-testing a semiconductor chemical gas sensor comprises the steps of: applying power to a heating element; obtaining a measurement from a temperature sensing element; adjusting the power applied to the heating element until the obtained measurement from the temperature sensing element reaches a desired measurement; obtaining a measurement from a gas sensitive element when the desired measurement is reached; and comparing the obtained measurement from the gas sensitive element to a reference measurement. An alternate method comprises the steps of: applying power to the heating element; obtaining measurements from the gas sensitive element and the temperature sensing element; adjusting the power applied to the heating element to cause a change in the obtained measurement from the temperature sensing element and obtaining a change in measurement from the gas sensitive element; and determining if the obtained change in gas measurement is consistent with the change in temperature measurement.

Abstract: A method and apparatus for diagnosing defects in electrochemical gas sensors, in which the water vapor pressure of the air surrounding a sensor is suddenly changed by changing to more dry or more humid air, thereby causing a sharp change in the acidity at the working electrode, and hence, a transient current from the sensor. The response of the sensor to the change in water vapor pressure is monitored and is used for sensor diagnostics. Lack of sensitivity of the sensor to the water vapor pressure change is an indication that the sensor does not have appropriate sensitivity to the gas to be detected. The method and apparatus are particularly useful for diagnostic testing of sensors without a gas filter.

Abstract: A method of filtering an oxygen sensor signal is provided. The method includes obtaining the oxygen sensor signal from the oxygen sensor on a periodic basis. The oxygen sensor signal is then compared to an average oxygen sensor signal value. If the oxygen sensor signal is greater than the average oxygen sensor signal value, a high signal counter is incremented. If the high signal counter is greater than a high signal count threshold, the oxygen sensor signal is forced to a high signal value. If the oxygen sensor signal is less than the average oxygen sensor signal value, a low signal counter is incremented. If the low signal counter is greater than a low signal count threshold, the oxygen sensor signal is forced to the low signal value. The high and low signal count thresholds correspond to a preselected period of time indicating a low or high signal trend within the oxygen sensor signal.

Abstract: A method of compensating a MOS gas sensor is described and which includes using a MOS gas sensor to provide a signal indicative of gas concentration of a target gas in an ambient; providing a signal representative of dew point of the ambient; and modifying the signal from the MOS gas sensor using the signal representative of dew point to simultaneously compensate for the effects of both temperature and relative humidity on the MOS gas sensor.

Abstract: Before starting an air-fuel ratio feedback control utilizing an air-fuel ratio sensor, activation of a wide-range air-fuel ratio sensor in an internal combustion engine is diagnosed by calculating heat transferred to and from the air-fuel ratio sensor whose output value varies in response to oxygen concentration in exhaust which varies according to the air-fuel ratio of an intake air-fuel mixture of the internal combustion engine, and estimating the activation time from the starting of the engine until the air-fuel ratio sensor is activated, based on said calculated result of the heat transfer. Alternatively, activation of the sensor is diagnosed under the condition that an output voltage of the oxygen concentration detecting unit of the sensor is fixed to a value either equal to or above a rich-side set voltage or equal to or under a lean-side set voltage, before starting the air-fuel ratio feedback control.

Abstract: An oxygen sensor includes a detector to be positioned between the ambient air and the exhaust gas, which generates a voltage corresponding to a difference in oxygen partial pressure therebetween. A controller performs monitoring of the output voltage from the oxygen sensor and determines an occurrence of fracture in the detector when detecting the generation of a lean signal, which is a signal indicating the above-described difference in the oxygen partial pressure is small, being frequent more than a certain value, and carries out an abnormality diagnosis to the oxygen sensor.

Abstract: An automatic system for calibrating gas sensors comprising a source of span gas and a source of zero gas, a means to control the flow of these gases to sensors. The system makes all required sensor value corrections and adjustments without human intervention.

Abstract: An exhaust gas sampling system for use in connection with the sampling of an internal combustion engine exhaust gas streams has a plurality of diluters arranged in a serial array along an axial extent. A source of engine exhaust gas is fluidically connected to the plurality of serially arranged diluters so as to supply an engine exhaust gas stream into each one of the plurality of serially arranged diluters in a serial manner. A source of dilution air fluidically is connected to each one of the plurality of serially arranged diluters so as to supply dilution air into each one of the plurality of serially arranged diluters.

Abstract: Explosive gas detectors are functionally tested by directing a brief aerosol spray discharge of a formulation selected to provide a visible spray discharge and from an aerosol dispenser pressurized with a hydrocarbon propellant. The propellant activates a properly functioning gas detector. The visible directional spray visually confirms delivery of propellant to the gas detector unit, so that a failure to activate is properly attributable to detector failure. A preferred formulation is one previously proven successful for the functional testing of electronic smoke detectors.

Abstract: An automatic calibration mode for a carbon dioxide sensor is based on using a zero gas. The sensor is designed to recognize a distinctive rate of change pattern of carbon dioxide concentrations that would be indicative of a zero calibration routine. This approach can be used for other infrared sensors.

Abstract: A method and apparatus for calibrating a sensor for determination of the concentration of a sterilant, e.g., hydrogen peroxide vapor, in a sterilization system.

Abstract: An impact force is applied to a sensing element to enlarge the size of a hidden crack to a visible level to reveal the presence of the hidden crack.

Abstract: Before starting an air-fuel ratio feedback control utilizing an air-fuel ratio sensor, activation of a wide-range air-fuel ratio sensor in an internal combustion engine is diagnosed by calculating heat transferred to and from the air-fuel ratio sensor, the output value of the wide-range air-fuel ratio sensor varies in response to oxygen concentration in exhaust which varies according to the air-fuel ratio of an intake air-fuel mixture of the internal combustion engine. The activation time from the starting of the engine until the air-fuel ratio sensor is activated is estimate based on the calculated result of the heat transfer. Alternatively, activation of the sensor is diagnosed under the condition that an output voltage of the oxygen concentration detecting unit of the sensor is fixed to a value either equal to or above a rich-side set voltage or equal to or under a lean-side set voltage, before starting the air-fuel ratio feedback control.