Abstract: The present invention relates to the monitoring of gas concentrations possible in very low ranges (i.e. low ppb and even ppt ranges) and especially use thereof in environmental monitoring, exposure assessment, bomb detection, and health studies. The invention can use a spatial and temporal assessment of gas concentrations that enables the sources of the gas in question to be located and identified which is useful in environmental and health field but can also be applied to other fields an example of which is detecting and locating explosives. This technology can uses small, light weight, and low power components that allow for the monitor to be portable and even worn on a person as a personal monitor. This technology can be used in stationary monitors as well.

Abstract: This invention relates to a system for testing the operation of a detection instrument, which comprises a first enclosure having at least two ports and containing a fluid comprising a substance detectable in gas form by the instrument, said fluid being present in part as a vapor phase and in part as a liquid phase in equilibrium with one another, said first enclosure being interconnected with the instrument such that the fluid contained in the first enclosure can be dispensed to the instrument via at least one port of said first enclosure; a second enclosure having at least one port and containing either the same or a different fluid in gas form as compared with the first enclosure, said second enclosure being adapted for selective dispensing of a known or ascertainable mass of the fluid contained therein via at least one port thereof, and being interconnected with the first enclosure such that said mass can be introduced into the volume within said first enclosure through at least one port thereof, thereby t

Abstract: A gas detection chamber in which a gas sensing element is provided to detect a component of a gas allowed into the gas detection chamber is heated by a heater, and an output of the heater is regulated by a heater regulator. The heater regulator is adapted to cause the heater to continue to heat the gas detection chamber (preferably but not necessarily, the output of the heater is caused to lower) when an anomaly detection device detects an anomaly of the gas sensing element.

Abstract: There is provided an inspection method of an oxygen sensor, which includes a sensing portion having a reference electrode, a sensing electrode and an oxygen ion conducting solid electrolyte layer arranged between the reference electrode and the sensing electrode. The inspection method contains the steps of reading a first output value of the oxygen sensor under a condition that the sensing portion of the oxygen sensor is subjected to a first inspection gas and then a second output value of the oxygen sensor under a condition that the sensing portion of the oxygen sensor is subjected to a second inspection gas different in oxygen concentration from the first inspection gas and judging the oxygen sensor to be defective or nondefective based on the first and second output values.

Abstract: A test adapter for the saturated vapor calibration of gas-measuring devices. The test adapter (2) has, in an adapter housing (15), a peripheral edge (7) for receiving a gas-measuring device and has a depression (10) for receiving the sample liquid in the area of the gas-sensitive surface of the gas-measuring device.

Abstract: A method is provided for indicating the useful service life of a gas filtration and purification system comprising steps of embedding two or more mass-responsive electronic sensors (e.g., surface acoustic wave devices) in a sorbent bed of a filtration cartridge, wherein the mass-responsive electronic sensors are coated with a non-conductive absorptive organic polymer; passing a gas containing a volatile chemical of interest through the filtration cartridge and in contact with the two mass-responsive electronic sensors; and measuring a difference in an electronic property between the two mass-responsive electronic sensors. In such a manner, the two mass-responsive electronic sensors act as internal references with respect to each other, thereby eliminating variations in temperature, interferents, pressure, and the like.

Abstract: A portable metered flow apparatus for accurately providing calibration gas from a calibration gas source to a gas monitoring instrument in order to permit calibration/bump testing of the instrument comprising a regulator and a gas delivery device that includes a solenoid valve, an electronic timing circuit, means for providing power to the solenoid valve and the electronic timing circuit, a power switch for activating the electronic timing circuit, means for activating the release of calibration gas; and optionally one or more LED lights. A method for calibration/bump testing of a gas monitoring device utilizing the portable metered flow apparatus is also provided.

Abstract: Method, apparatus, and system are utilized for testing the performance of a gas monitor against predetermined monitor characteristics to determine if performance of the gas monitor is validated in a manner whereby testing gas is directly delivered to the gas sensor.

Abstract: Embodiments of apparatuses, articles, methods, and systems for measuring sensor drift characteristics are generally described herein. In some embodiments, a system having a sensor platform to receive a sensor and measure drift characteristic of the sensor is disclosed. The system may further include a data acquisition device coupled to the sensor platform to receive the measured drift characteristic and to compare them to acceptance criteria in order to determine an acceptability of the sensor. Other embodiments may be described and claimed.

Abstract: In manufacturing a multilayered gas sensor element which includes a sensor cell for measuring a specific gas concentration in a measured gas, a main body portion including a plurality of laminated ceramic substrates, and a plate heater portion generating heat in response to supply of electric power, which are integrally laminated in a predetermined order, a multilayered body of green sheets forming the main body portion and the heater portion is sintered into a multilayered gas sensor element, and then at least both side surfaces of the multilayered gas sensor element extending in a longitudinal direction are processed by grinding, so as to remove surface defects.

Abstract: The invention relates to a method for calibrating the relative content (RH) of water. According to the invention, at least one calibration point is defined at a known partial pressure (Pw) of water vapour and sensor temperature of the sensor. According to the invention, at the same known partial pressure (Pw) of water the sensor (2) is heated and, at least one increased temperature point, both the relative content (RH) and the temperature (T) are measured simultaneously.

Abstract: A method of evaluating a measuring device for measuring, in normal operation, a diffusion capacity of a person's lungs by measuring a change of concentration of a gas species in a mixture, when the mixture is inhaled and subsequently exhaled by the person or imposed by an artificial ventilator, the method comprising the steps of: (a) receiving the mixture in a compartment; (b) circulating gas from the compartment back to the compartment through a circulation circuit; and (c) selectively reducing partial pressure of the gas species in the circulation circuit to a predetermined level. A device for implementing the evaluation method is also disclosed.

Abstract: A method and a system for monitoring the functional capability of a particle detector connected downstream, in the flow direction, of a particle filter, in which particles occurring upon the regeneration of the particle filter, in particular ions, are detected by the particle detector and the resultant measurement finding are compared with an expected finding. The measurement and evaluation are effected in a control and evaluation unit. The invention enables monitoring of the functional capability of a particle detector that does not interrupt normal operation and thus increases the reliability of the entire system.

Abstract: An apparatus for determining a leak rate of a gas from a closed valve is disclosed. The apparatus may include a vacuum pump, a pressure measuring device, a monitoring device, and a computer. The vacuum pump may be configured to couple downstream of the closed valve and decrease the pressure of the downstream side of the closed valve. The pressure measuring device may be configured to couple with the downstream side and determine the pressure. The monitoring device may be configured to couple with the downstream side and monitor a gas, where the gas may be emitted from the closed valve and be characterized by a mass. The monitoring device may further be configured to determine the mass. The computer may be configured to control the vacuum pump based on the pressure, and determine the leak rate of the gas based at least in part on the mass.

Abstract: A system for testing and calibrating gas sensors with gas stored in a strip of packets. The strip may be fed into a chamber having a defined volume of air. A packet may be punctured with a mechanism to release one or more gases into the volume of air to result in an air-gas mixture. New air may be moved into the chamber to push the mixture out of the chamber to a sensor for testing and/or calibration. Then another packet may be punctured to release one or more gases into the volume of new air in the chamber for another air-gas mixture. This mixture may be moved out of the chamber, in the same manner as the previous mixture, to another sensor for testing and/or calibration. This procedure may be repeated with additional packets on the strip.

Abstract: A method of monitoring a performance of an oxygen sensor is disclosed. One embodiment comprises determining a first air/fuel ratio from a signal from an exhaust oxygen sensor; determining a second air/fuel ratio from a temperature upstream of the particulate filter, a pressure differential across the particulate filter and one or more of an airflow into the engine and a fuel flow into the engine; comparing the first air/fuel ratio and the second air/fuel ratio; and diagnosing an error condition of the oxygen sensor if the first air/fuel ratio does not meet a predetermined condition relative to the second air/fuel ratio.

Abstract: A plateau phase of a test signal of an exhaust gas probe located in a catalytic converter is detected following a jump from a preset rich air/fuel ratio in a combustion chamber of one cylinder to a preset lean air/fuel ratio, the plateau phase being obtained following the jump, and the duration is determined as a storage period. A plateau phase of the test signal, which is obtained following a jump from a preset lean air/fuel ratio to a preset rich air/fuel ratio, is detected following the jump, and the duration of the plateau phase is determined as an evacuation period. An allocation rule for assigning the test signal to a detected air/fuel ratio is adjusted according to the storage period and the evacuation period. To calibrate the exhaust gas probe, the allocation rule is adapted according to a plateau value of the test signal during the plateau phase.

Abstract: A system for diagnosing an exhaust temperature sensor in an engine exhaust, the exhaust further including an emission control device, the system comprising an exhaust temperature sensor disposed in the exhaust pathway for indicating temperature; an air/fuel ratio sensor having a heater, the air/fuel ratio sensor disposed in the exhaust pathway; and a control system, the control system enabling and disabling the air/fuel ratio sensor heater based on operating conditions, the controller further adjusting fuel injection to provide a desired air-fuel ratio based on feedback from the air/fuel ratio sensor when the heater is enabled, and determining degradation of the exhaust temperature sensor based on a signal from the air/fuel ratio sensor when the heater is disabled.

Abstract: A circuit configuration for operating a gas sensor is described, including a reference gas space in which an electrode is situated which is supplied with a reference gas pump current to maintain the concentration of the reference gas. A diagnostic system determines a concentration change of the reference gas via a change in the reference pump current and a time-based evaluation of the sensor signal of the gas sensor.

Abstract: A calibration assembly generates elemental mercury and oxidized mercury for calibrating components of a mercury monitoring system, including making necessary adjustments to efficiencies of a mercury compound converter and an elemental mercury detector. The calibrator generates an elemental mercury sample having a known elemental mercury concentration, [Hg0]1 and combines an oxidizing component with the elemental mercury sample, thereby producing a reduced concentration of elemental mercury [Hg0]2 within the sample. The calibrator measures the concentration of elemental mercury [Hg0]2 within the sample and calculates a difference between the known elemental mercury concentration, [Hg0]1 and the reduced concentration [Hg0]2. The difference between [Hg0]1 and [Hg0]2 is substantially equal to the concentration of oxidized mercury produced by the calibrator.

Abstract: Embodiments of the present invention relate to a gas sensor comprising a flow channel, a concentration modulator positioned in the flow channel, a gas generator in contact with the flow channel, one or more gas detectors positioned downstream of the concentration modulator and gas generator and a pump.

Abstract: The calibration tool is provided for use with a detector, such as a detector for detecting trace amounts of one or more substances of interest. The calibration tool includes a body with at least one reservoir for retaining the calibration solution therein. A nib projects from the body and communicates with the reservoir. The nib can be wiped across a detection surface and the detection surface then may be presented to a detector. The detector then can be calibrated for the particular substance of interest in the calibration solution. The calibration tool may include plural reservoirs isolated from one another and plural nibs for applying the calibration solution to a detection surface.

Abstract: A leak test apparatus includes a housing having an interior sized for retaining a plurality of instrument components including a control unit. A sniffer gun is linked to the instrument components, the sniffer gun having an intake point, and a test leak includes a gas reservoir, a constriction, an opening suited for introducing the intake point of said sniffer gun, and a temperature sensor. The temperature sensor is linked, either by means of a wired connection or wirelessly to the control unit for signal transfer.

Abstract: A method and apparatus for calibrating a sensor used to sense the concentration of vaporized hydrogen peroxide (VHP). A concentration of liquid hydrogen peroxide in an aqueous solution is determined and correlated with a corresponding concentration of vaporized hydrogen peroxide indicative of an “actual” vaporized hydrogen peroxide concentration. An error value is determined by comparing the “actual” vaporized hydrogen peroxide concentration to a “measured” vaporized hydrogen peroxide concentration, indicated by the sensor being calibrated. The error value is used to properly calibrate the sensor.

Abstract: A method and apparatus for measuring target gas concentrations in an atmosphere. The method and apparatus emit in the atmosphere a laser beam tuned to a molecular absorption line of a target gas, receive a reflected signal affected by gas absorption of the target gas in the atmosphere, divide and direct the received signal into a first optical path and a second optical path including in one of the paths a correlation gas cell filled with a predetermined concentration of the target gas, detect transmitted signals through the first optical path and the second optical path, and calculate a target gas concentration by comparing a first signal transmitted through the first optical path to a second signal transmitted through the second optical path.

Abstract: System and method for calibrating a sensor comprises a detector capable of detecting electromagnetic radiation at least at a radiation wavelength of interest, an analyzer capable of determining concentration values in response to the detected radiation, and a calibrator capable of automatically calibrating the analyzer in response to at least one concentration value. A method for operating a calibrator comprises receiving an initiation signal capable of initiating the calibrator, automatically obtaining concentration values in response to the initiation signal, and automatically determining a calibration value from the obtained concentration values. In an embodiment, the calibrator automatically determines when a calibration gas equilibrates within a sample chamber.

Abstract: A method for a method for calibrating a system configured to analyze exhaust gas produced by a fluid consuming source is disclosed. The method includes directing a first flow of exhaust gas toward an analyzer that is configured to measure at least one component. The method also includes establishing a first value indicative of a measurement of the at least one component within the first flow of exhaust gas. The method also includes removing a first quantity of fluid from the fluid consuming source and delivering a second quantity of fluid into the first flow of exhaust gas. The second quantity of fluid is a portion of the first quantity of fluid. The method also includes at least partially combusting the first flow of exhaust gas and the first quantity of fluid upstream of the analyzer and establishing a second value indicative of a measurement of the at least one component within the exhaust gas and the at least a portion of the first quantity of fluid.

Abstract: An apparatus for sensing a constituent in an environment including a sensor circuit and a suppression circuit. The sensor circuit has a sensor element and an operating state control element. The sensor element senses the constituent by presenting an electrical parameter which varies as a function of a degree of the constituent. The control element maintains the sensor at a preferred operating state. A detected electrical parameter of said sensor element is subject to error resulting from a leakage of electrical current between the control element and the sensor element. The suppression circuit reduces or stops the leakage to reduce the error.

Abstract: In a process for diagnosis of a lambda probe (6) associated with the exhaust gas catalytic converter (3) of an internal combustion engine (1), it is proposed that for a known first and second exhaust gas mass flow {{dot over (m)}1, {dot over (m)}2} through the exhaust gas catalytic converter (3) it is measured how large the respective time delay (?t1, ?t2) is until a sudden change of the lambda signal (?a) upstream from the exhaust gas catalytic converter (3) appears for the lambda signal (?b) of the lambda probe (6) associated with the exhaust gas catalytic converter (3), and that based on the measured time delays (?t1, ?t2) it is determined how large the catalytic converter-induced portion (?tcat1, ?tcat2) which is dependent on the exhaust gas mass flow ({{dot over (m)}1, {dot over (m)}2}) is and how large the probe-induced portion (?tprobe1, ?tprobe2) of the time delays (?tprobe1, ?tprobe2) which is essentially independent of the exhaust gas mass flow ({{dot over (m)}1, {dot over (m)}2}) is, the probe-indu

Abstract: Self-calibrating apparatus and methods for dilution of an analyte-containing fluid, and in particular for dilution of analyte concentrations beyond the normal measurement range of a detector, without the requirement for other detectors. The apparatus is preferably a respirator test system for determining respirator mask fit in the presence of high aerosol challenge concentrations.

Abstract: A gas sensor is provided that is delimited from the environment with a preferably replaceable cap (8) made of a porous, gas-permeable and water-impermeable material, especially sintered PTFE. The gas sensor is protected against environmental moisture and can be permanently provided with the cap (8) and with a special calibrating adapter (9) both during the gas measurement and during the necessary calibration. Due to the special design of the cap (8) and the calibrating adapter (9), the gas sensor offers the possibility of remote calibration, which can be carried out with high accuracy and is independent from weather effects, especially wind.

Abstract: Method, apparatus, and system are utilized for testing the performance of a gas monitor against predetermined monitor characteristics to determine if performance of the gas monitor is validated in a manner whereby testing gas is directly delivered to the gas sensor.

Abstract: A method of calibrating a gas sensor that generates an output related to the concentration of a sensed gas, the method comprising: i) obtaining the value of said output or a related value at each of a set of known values of a first variable and at each of a set of known values of a second variable, one of the variables being gas concentration; ii) for each value of said second variable, determining a first best fit function relating said output or related value to the first variable, each best fit function utilizing at least one coefficient whose value is determined; iii) for the, or the corresponding, coefficient values from each of the first best fit functions, determining a second best fit function relating said coefficient to the second variable, and replacing the coefficient values in the first best fit functions by the second best fit function, and, iv) repeating step iii) for each further coefficient, if any, in the first best fit functions so as to generate a final function relating said output or

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

Abstract: Embodiments of the present invention relate to a gas sensor system comprising a gas sensor, a fluid reservoir enclosing a fluid and in proximity to the gas sensor and a membrane positioned between the gas sensor and fluid reservoir, wherein the membrane allows a sufficient amount of a test gas generated from the fluid to contact the gas sensor for testing. Embodiments also relate to a method of testing a gas sensor, the method comprises contacting reagents within a fluid reservoir, generating a test gas and contacting a gas sensor with the test gas sufficient to test the gas sensor.

Abstract: A flex fuel sensor is deployed in conjunction with the fuel transfer line (e.g. around a plastic fuel line) or at the bottom/side of a fuel tank. An RF signal of a constant frequency may be generated across a resonant circuit, which comprises of an inductor and a PCB trace capacitor, capacitor plates, semi cylindrical capacitor plates, or the like. Electromagnetic radiation is propagated into the passing fuel in the transfer pipe. The conductivity and dielectric properties of the fuel change the capacitance of the trace capacitor/capacitor plates. These changes are proportional to ethanol/alcohol content of the fuel and are preferably detected by a microcontroller, or the like, and then transmitted to a flex fuel vehicle Engine Management System.

Abstract: In an abnormality diagnostic device and an abnormality diagnostic device for an air-fuel ratio sensor that detects the air-fuel ratio of exhaust gas of an internal combustion engine, a system extending from a fuel injection valve to the air-fuel ratio sensor is model by a first order response delay, and a parameter in the first order response delay is identified based on an input air-fuel ratio that is given to the air-fuel ratio sensor and an output air-fuel ratio that is output from the air-fuel ratio sensor. Then, the presence/absence of abnormality regarding a predetermined characteristic of the air-fuel ratio sensor is determined based on the parameter identified. Thus, abnormality is diagnosed regarding individual characteristics of the air-fuel ratio sensor.

Abstract: A sensing device for increasing sensor accuracy in stagnant air or gas environments has a piezoelectric air mover positioned proximate a sensing element. The piezoelectric air mover blows or draws air or gas from the environment across the sensing element to eliminate the stagnant gas condition and thereby increase the speed and accuracy of measurements with the sensing element.

Abstract: Method, apparatus, and system are utilized for testing the performance of a gas monitor against predetermined monitor characteristics to determine if performance of the gas monitor is validated in a manner whereby testing gas is directly delivered to the gas sensor.

Abstract: In a method for checking the lambda value ? indicated by a binary lambda probe, the lambda probe being situated in the exhaust line of an internal combustion engine and provided downstream from a catalyst having oxygen storage capacity, the invention provides that the time progression of the voltage signal U? is plotted in the range of the lambda value ?actual of 1.0 indicated by the lambda probe until a first inflection point W1 and a second inflection point W2 of the voltage signal U? have been detected, the time derivative dU?/dt of the voltage signal is generated, the jumps S1, S2 in the time derivative dU?/dt which occur at the inflection points W1, W2 are compared to one another, and based on the comparison of the jumps S1, S2 the indicated lambda value ?actual of 1.0 is checked. According to the invention, the actual lambda value ?target of 1.

Abstract: An analysis method for a substrate processing apparatus capable of accurately detecting a state in a housing chamber. Emission intensities of processing gas before being introduced into the chamber and processing gas having passed therethrough are measured before an inter-chamber part is replaced. If an emission intensity measured after the replacement coincides with that measured before the replacement, an emission intensity of the processing gas having passed through the chamber is measured, and a variation between the emission intensities of the processing gas having passed through the chamber measured before and after the replacement is calculated. After start of plasma processing on wafers, an emission intensity of the processing gas having passed through the chamber is measured and the variation is removed therefrom to calculate an emission intensity really representing a state in the chamber, thus detecting an end point of plasma processing therefrom.

Abstract: Embodiments of the invention provide novel, industrially applicable, and non-obvious apparatus and methods for automatically, routinely, and accurately calibrating a trace detection portal. Embodiments of the apparatus include a calibrant container; a substance (or substances) uniquely identifiable by a trace detection portal as a calibrant; unique placement of the calibrant container's outlet relative to a substance collection port of a sample collection chamber; and/or computer executable instructions that, when executed by a computer processor, cause a consistent release of a measured amount of calibrant into the sample collection chamber upon command and/or at pre-determined time intervals.

Abstract: An electronic gas sensor signal conditioner which can automatically adapt to a wide variety of commercial off-the-shelf sensors and provide a digital output in a standard, easily used format. The signal conditioner has analog and digital sections. The analog section includes a sensor excitation sub-section and a signal amplification sub-section. The digital section comprises a microcontroller and controls the analog section. The digital section also converts the signal from the analog section into digital form, reads the sensor TEDS (Transducer Electronic Data Sheet), applies calibration constants and converts the signal into a standard, easily readable digital format.

Abstract: A system and method is provided for obtaining calibration curves for CO and CO2 during laboratory calibration of one or more remote emissions sensing (RES) instruments, and for self-calibration of on-road RES instruments to compensate for changes in background CO and CO2 column densities.

Abstract: A gas test system (300) is disclosed comprised of a flow loop (302), a blower system (304), a temperature control system (306), a reference meter system (308), and a unit under test (UUT) system (310). The UUT system connects a unit under test (UUT) to the flow loop. The blower system receives the gas under pressure at an inlet (321), and generates a high flow rate of the gas out of an outlet (322) while generating a low pressure rise from the inlet to the outlet. The temperature control system receives the flow of gas from the blower system and controls the temperature of the gas. The reference meter system and the UUT in the UUT system measure a property of the gas circulating through the flow loop. The measurements of the reference meter system can be compared to the measurements of the UUT to calibrate the UUT.

Abstract: An air-fuel ratio sensor has an exhaust-side electrode and an atmosphere-side electrode. The atmosphere-side electrode is disposed in an atmosphere layer that communicates with the atmosphere. Since the air-fuel ratio sensor is disposed in an exhaust passage, exhaust gas enters the atmosphere layer if a sensor crack occurs. Ordinarily, forward voltage is applied to the air-fuel ratio sensor to obtain an output thereof in accordance with the air-fuel ratio. Immediately after the applied voltage is switched to reverse voltage, sensor current i1 in accordance with the impedance flows, regardless of the presence/absence of a sensor crack. After that, the sensor current converges to a value i2 that is in accordance with the oxygen concentration in the atmosphere layer. The presence/absence of a sensor crack is determined by comparing the value obtained by correcting i2 by i1, with a criterion value.

Abstract: A first gas sensing element is provided in a first position to measure a concentration of a gas continuously, and a second sensing element is provided in a second position to measure the concentration of the gas intermittently. The second position is in close proximity to the first position. A deterioration determination unit is connected with the first and second sensing elements to make a determination as to whether the first sensing element becomes deteriorated, by comparing output values from the first and second sensing elements. A power controller is configured to supply the second sensing element with electric power throughout waiting periods during which the second sensing element stops measuring the concentration of the gas, and an amount of the electric power supplied throughout waiting periods is smaller than that supplied throughout operating periods during which the second sensing element continuously measures the concentration of the gas.

Abstract: An element crack detecting apparatus for an oxygen sensor detects a sensor output voltage for an abnormality detection period after a fuel cut-off is started during operation of an engine. When the output voltage becomes negative, an abnormality counter is counted up. When the abnormality counter value reaches a determination value, it is determined that the element crack is present. The abnormality detection period is variably set in response to an engine rotational speed, an intake air quantity and the mixture state immediately before the fuel cut-off is effected. The determination value is variably set in response to the oxygen sensor temperature and the mixture state immediately before the fuel cut-off is effected. Further, the determination value is variably set in response to a magnitude of the negative voltage of the oxygen sensor.

Abstract: A measuring apparatus and method for use in measuring diffusible hydrogen concentrations in materials, structures, and other objects. In an embodiment of the invention for use in welding applications, the measuring apparatus (10) includes a sensor assembly (20) that, with an included sealing member (40), defines a sample area (17) on a weld bead (16) from which hydrogen evolves into a sample volume (18) defined by the sealing member (40), a sensor housing (34) and a sensor (22) of the sensor assembly (20). The hydrogen reacts with a sensing layer (28) and a reflector layer (30) positioned on the end of an optical fiber (24), all of which are included in the sensor assembly (20) and are sealably positioned within the sensor (22).

Abstract: An abnormality detecting apparatus includes an air/fuel ratio sensor that detects an air/fuel ratio within a range including the stoichiometric air/fuel ratio, an admittance detector for detecting an admittance of the sensor, and a temperature detector for detecting a temperature of the sensor. This apparatus detects an abnormality of the sensor when the detected temperature is at a first temperature which is higher than an activation temperature of the sensor and the detected admittance is less than a first determining value. The apparatus also detects a disconnection abnormality of the sensor when the detected temperature is at a second temperature, which is higher than a minimum temperature at which admittance can be detected for a normally operation and lower than the first temperature, and the detected admittance is less than a second determining value for determining disconnection of the sensor which is less than the first determining value.