Abstract: A method of compensating for baseline or span drift in gas sensing equipment includes obtaining gas concentration data over a time period and identifying a quiescent period within that time period. The method compares a component concentration corresponding to the quiescent period with one or more additional component concentrations relating to different quiescent periods and calculates an estimated background gas concentration for a predetermined number of time periods. The estimated background concentration is then compared to preset, or expected, background concentration, and a correction value is calculated. For baseline drift, a correction value is determined to be the difference between the estimated background concentration and the preset (expected) background concentration. For span drift, a correction value is determined to be the ratio of the estimated background concentration to the preset (expected) background concentration.

Abstract: In analyzing the concentration of an objective component contained in a sample gas by a gas analyzer, an output of the gas analyzer is corrected at a fixed point by applying the relationship between the concentration of a coexistent gas and a span sensitivity of the objective component to make it possible to simply correct the effect of the coexistent gas. In addition, by inputting, at the time of the calibration of the gas analyzer, the information on to what extent the base gas composition differs from the average amount of the actual sample along with the concentration amount of the objective component in the calibration gas, the sensitivity adjustment coefficient is determined by taking into account the effect amount which is previously stored in the gas analyzer, by which the effect amount of the span sensitivity by the difference of the base gas compositions in the calibration gas and the sample gas is suppressed, and the effect of the coexistent gas is canceled to the best possible extent.

Abstract: A calibration apparatus for checking the accuracy of DLco testing machines includes a pair of syringes mounted side by side in a frame and joined by a valve controlled gas passageway to a coupling adapted to mate with the testing machine. The first syringe receives gas from the testing machine and the second syringe has a chamber from which gas of a known concentration is returned to the testing machine. The chamber of the second syringe is flow connected by a valve to a source of test gas. The gas passageway is constructed in such a manner to reduce dead air space and to allow purging with test gas to eliminate contamination with ambient air or gas of previous tests.

Abstract: A plug for providing a predetermined flow rate of leakage gas from a sealed package for purposes of calibration of gas measurement instruments, the plug having an axial passage therethrough with a threaded interior wall; and a bolt for threading into the plug axial passage, the bolt having an axial passage therethrough, and an insert for insertion into the bolt axial passage, the insert having a predetermined size opening for permitting only a predictable flow of leakage gas through the plug.

Abstract: A method for calibrating a personal air sampler. A desired flow rate is set, the actual rate measured and recorded through a plurality of runs, the results are automatically averaged and compared to the desired flow and the pump is automatically adjusted accordingly. The process may be repeated for a plurality of selected flow rates, and a best-fit curve computed to cover the entire range. Stability is tested by a series of sets of runs to determine erratic behavior, and an overall calibration is conducted by performing such a series of runs at each of several set point flows.

Abstract: Changes in the concentration of a chemical, such as a gas, are determined using a non-linear chemical sensor which is subject to shifts in calibration over time. In order to minimize errors caused by such shifts in calibration a first infrared signal (Ig(1)) is measured and using an absorption value under an assumed chemical concentration (C(1)), a zero chemical signal Io(1) is calculated using the known physical law and mathematical relation Absorption=1−Ig/Io. A second infrared signal (Ig(2)) is then measured and the absorption value is calculated using the previously calculated zero chemical signal. A second concentration (C(2)) is then determined and the change in concentration is calculated by subtracting C(2) from C(1).

Abstract: The invention concerns a method for the realignment of peaks in gas chromatographic analyses after the replacement of the used capillary column with a nominally equal one, wherein a K coefficient characteristic of the column is preventively calculated by flowing carrier gas in the column under stabilized conditions of pressure and flow rate and of the column temperature, said K coefficient being stored in a memory of the gas chromatographic system. Said K coefficient is used to correlate at least two of the above mentioned parameters in subsequent analyses, obtaining an automatic realignment of peaks. The invention also concerns the analytical equipment to perform the method, and the capillary gas chromatographic column characterized as reported above.

Abstract: A method for validating permeation measurements through closed containers including closure members, by making a first measurement of permeation through a container of a first size, and making a second measurement of permeation through a container of a second size, both with the same closure members, and subtracting the permeation measurement contributions respectively made by the closure members.

Abstract: A method for detecting combustible gases or vapors using a combustible gas sensor or pellistors includes the steps of keeping the combustible gas sensor or the pellistor beads inactive until an oxygen sensor indicates a variation from a reference level of oxygen, such variation representing the potential presence of combustible gases or vapors.

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 concentration measuring apparatus is provided which measures the concentration of a given gas using a gas sensor. The gas sensor includes a sensor element producing a gas concentration signal indicative of the concentration of the gas, a heater heating the sensor element, and an insulator disposed between the sensor element and the heater. The apparatus includes a heater control circuit which may provisionally supply electrical power to the heater by applying a Pulse-Width-Modulated signal. The heater control circuit performs a switching operation to supply power to the heater cyclically. The apparatus corrects an error contained in the gas concentration signal arising from a leakage current flowing into the sensor element through the insulator during the switching operation of the heater control circuit.

Abstract: A method and an apparatus for calibrating a dissolved oxygen analyzer are disclosed. In the method, a zero point is first determined and set on the analyzer by filling into the analyzer a saturated aqueous solution of an oxidizer that contains 0 ppb oxygen. A span point is then set on the analyzer by filling a sample solution in the analyzer and flowing a cell current through a Faraday electrode until a 20 ppb oxygen is produced and then setting the point as a span point for completing a two-point calibration process. A slope for calibration can be obtained between the zero point and the span point.

Abstract: A method of speeding startup of a MOS gas sensor having a sensor element for sensing a target gas, and a heater configured to heat the sensor element, and which is responsive to a voltage applied thereto. The heater has an operating temperature which is selectively maintained by applying a first voltage thereto, and the heater further has a maximum recommended temperature which is selectively maintained by applying a second voltage thereto. The maximum recommended temperature is higher than the operating temperature, and the second voltage is higher than the first voltage. The method includes providing a third voltage to the heater which is greater than the second voltage for a predetermined amount of time which is selected to increase the temperature to a level not greater than the maximum recommended temperature in a shorter time period than if the second voltage is applied and maintained. A MOS gas sensor system and a fuel cell system also employ such a method.

Abstract: A device is provided for generating a defined relative humidity in a gas. This device includes a saturator chamber connected by at least one connecting line to a measuring chamber. The relative humidity in the measuring chamber can be adjusted by varying the pressures in the saturator chamber and in the measuring chamber. A valve unit is arranged in the connecting line. The valve unit and the portion of the connecting line located between the valve unit and the saturator chamber are in thermal contact with a heating device.

Abstract: The invention is directed to an arrangement for detecting a gaseous component in a gas flow which reaches a measuring chamber (4) via a sample intake line (3). The arrangement includes a flow throttle (8) in the sample intake line (3) and has a pressure sensor (9) for detecting the pressure at the inflow end of the flow throttle (8). The pressure sensor (9) can also be used to measure the ambient pressure. A flow detector (10) for generating a zero-flow signal is provided at a position along the sample intake line (3).

Abstract: Periodic forced stimulations are asserted on setpoint values for a lambda control and a system response of a lambda control loop is simulated by a model that includes a sensor delay time as the model parameter. Amplitude gains of the model and the system are compared with each other and adapted according to the result of the comparison of the model parameters. If the adaptation value lies above a threshold, a lambda probe is classified as defective.

Abstract: The present invention is directed to a new and improved apparatus and methods for calibrating environmental air monitor. A new calibration kit comprising a gas cylinder containing calibration gas, a preset regulator valve, a flow matching valve and tubing is disclosed which overcomes many of the prior art disadvantages. The flow matching valve compensates for deviation in calibration gas flow conditions and thus eliminating the need of a sampling bag. The flow matching valve modifies the preset regulator valve by compensating loss of pressure or flow going to the sensor in the environmental air or gas monitor. In addition when an abundance of pressure or flow is transmitted to the monitor, the flow matching valve “vents-off” the excess calibration gas. A method for calibrating a gas or air monitor is also disclosed. The method and apparatus permits a laminar flow, over a sensor located in the air monitor, of constant quantity and quality that is critically necessary for calibrating air monitors.

Abstract: Apparatus for testing the operation of a carbon monoxide alarm of the type having a casing and a CO sensor extending therefrom, includes a housing sized and configured to receive the casing and to form a gas chamber in communication with the sensor, a source of CO gas, comprising a flammable substance which generates CO gas when burned, and a holder located within the housing for holding the source while the source is being burned. The CO source generates a concentration of carbon monoxide gas within the chamber which is above a pre-selected threshold for a sufficient period of time to trigger an alarm condition.

Abstract: Apparatus for measuring concentration of oxygen includes a plurality of status displays, identifying concentration status relative to a plurality of thresholds, an alarm for immediate and prominent identification of status relative to a threshold of particular significance, and a quantitative display indicative of an actual concentration. Although measurements are performed and results are indicated relative to a number of thresholds, only a single calibration procedure is required, using only a single calibration gas. The apparatus is calibrated by adjusting a circuit parameter of one of the circuit components to vary a sensed output value to correspond to a narrow range surrounding the known concentration of the calibration gas. Both the circuit parameter and the actually sensed output value are stored. In a monitoring operation, the circuit parameter is retrieved to reset the circuit component to its calibrated setting.

Abstract: In a method for testing a measuring sensor for the determination of an oxygen concentration in a gas mixture, the measuring sensor supplies a detection voltage furnished by a Nernst measuring cell and corresponding to the oxygen concentration. The detection voltage is evaluated by a circuit arrangement and is picked off between a first electrode exposed to the gas mixture and a second electrode exposed to a reference gas. The measuring sensor is heated to operating temperature. The Nernst measuring cell is exposed to a constant test voltage and a gas mixture with a well-defined oxygen concentration and a measuring current of the Nernst measuring cell is evaluated.

Abstract: A gas analyzer comprising a pump unit and autocalibration means, characterized in that the gas analyzer is connected to a storage tank having a calibrated leak and filled with a mixture of n gases having different masses, and wherein the partial leakage flow of each of said n gases which through said calibrated leak is known.

Abstract: The method and system disclosed in the publication relates to an improvement in measurement accuracy of a gas concentration sensor (1) such as capacitive humidity sensor (1), the method comprising the steps of measuring a parameter of the sensor (1), such as its resistance or capacitance, that is sensitive to the gas or its concentration being measured, and simultaneously changing the temperature of the sensor (1) in a cyclic manner. According to the invention, the parameter of the sensor (1) being measured is measured at least essentially continuously, at least N times 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: The present invention is directed to a new and improved apparatus and methods for calibrating environmental air monitor. A new calibration kit comprising a gas cylinder containing calibration gas, a preset regulator valve, a flow matching valve and tubing is disclosed which overcomes many of the prior art disadvantages. The flow matching valve compensates for deviation in calibration gas flow conditions and thus eliminating the need of a sampling bag. The flow matching valve modifies the preset regulator valve by compensating loss of pressure or flow going to the sensor in the environmental air or gas monitor. In addition when an abundance of pressure or flow is transmitted to the monitor, the flow matching valve “vents-off” the excess calibration gas. A method for calibrating a gas or air monitor is also disclosed. The method and apparatus permits a laminar flow, over a sensor located in the air monitor, of constant quantity and quality that is critically necessary for calibrating air monitors.

Abstract: An inspection apparatus for gas detectors is disclosed which comprises an open-feasibly air-tight testing reservoir in which gas detectors to be tested can be positioned, an air-tight dispensing reservoir for mixing the gas to be tested, a vacuum device for making the testing reservoir and the dispensing reservoir in vacuum, a gas supply device for supplying at least a standard gas and a diluting gas to the dispensing reservoir, and a controlling means for controlling the dispensation of the gases to each of the above-described components of the invention. By means of the invention, the executions of the mixing of the gases and the detection of the gas detector are substantially simultaneous and thus the time consumption as well as the amount of required gas are reduced. Moreover, an automatic control is available when the inspection apparatus of the invention is equipped with a computer.

Abstract: An automotive emission control module has an emission control valve containing a main flow passage having a valve member that controls fluid flow through the flow passage. An internal pressure sensing passage communicates pressure at one side of an orifice in the main flow passage to a pressure sensor. The pressure sensor and a fluid pressure regulator valve are integrated with the body of a fluid-pressure-operated actuator that operates the valve member. The module is calibrated and tested in a test stand, and can be re-calibrated after installation in an automotive vehicle.

Abstract: A humidity detector has a sensor with an electrical characteristic that varies as a function of humidity and a transmitter circuit which produces an output signal in response to the capacitance of the sensor. The humidity detector is calibrated by alternately connecting devices in place of the sensor which simulate performance of the sensor at two reference humidity levels. While each device is present, the transmitter circuit is adjusted so that the output signal indicates the respective reference humidity level. Next, the sensor is connected to the transmitter circuit and exposed to a known humidity level. Then the transmitter circuit is adjusted so that the output signal indicates the known humidity level.

Abstract: An improved fuel control in which the transfer function of a wide-range exhaust gas oxygen sensor is automatically and periodically learned or re-learned in the course of vehicle operation. The oxygen sensor is calibrated at two different operating conditions: at a stoichiometric air/fuel ratio, and at a fuel cut-off or free-air ratio. The first operating condition occurs during steady state operation when a switching sensor disposed in the exhaust gas stream downstream of the catalytic converter indicates that the engine is being fueled at the stoichiometric air/fuel ratio. The second operating condition occurs when engine fuel is shut off, either during vehicle deceleration, or when the engine is turned off. Once both calibration points have been determined, the transfer function of the wide range sensor is adjusted to match the stored voltages, and engine fueling is thereafter based on the adjusted transfer function.

Abstract: A method for calibrating a personal air sampler. A desired flow rate is set, the actual rate measured and recorded through a plurality of runs, the results are automatically averaged and compared to the desired flow and the pump is automatically adjusted accordingly. The process may be repeated for a plurality of selected flow rates, and a best-fit curve computed to cover the entire range. Stability is tested by a series of sets of runs to determine erratic behavior, and an overall calibration is conducted by performing such a series of runs at each of several set point flows.

Abstract: A forming method for a calibration curve in an infrared gas analyzer. The forming method minimizes the systematic error that occurs in the infrared gas analyzer improves measuring precision. The forming method modifies a method in which gases having different concentrations are supplied to an infrared gas analyzer. The gas analyzer has the outputs corresponding to the gas concentrations, and samples the gas concentrations as a plurality of points, the number of which is not less than four. A calibration curve is approximated by up to a fourth-order polynomial using a method of least squares based upon the measured values of not less than 4 points thus sampled. In carrying out the above-mentioned polynomial approximation, an inverse number of the square of the divided ratio at each point of the calibration curve is used so as to carry out a weighting operation.

Abstract: A zirconium oxide shell forms a chamber of fixed volume, and a controller monitors voltage across the shell indicative of difference between inside and outside oxygen levels, applying a signal to pump oxygen. Pumping is effected to empty the chamber, to develop an internal reference, for example by comparison to ambient air, for calibration, and thereafter to substantially continuously null the difference, i.e., to track the oxygen level of a sample environment. Integrated pump current yields a measure of the oxygen added to or removed from the chamber. A suitable material for forming the sensor is a mixture of about 91% zirconium oxide and 9% yttrium oxide, which is formed to shape as a paste or slurry and sintered at about 1400° C., and then platinum coated, for example by a CVD process, to form porous electrodes on each surface. The controller may apply a sequence of current pulses, and check the Nernst cell output indicative of &Dgr;P across the wall, until &Dgr;P=0.

Abstract: According to the present invention, there is provided a measuring instrument with a memory or measuring electrodes each having a memory, which does not require setting of a calibration or correction value at each replacement of the electrode, permits automatic recognition of information such as the model name or the manufacture No. of the electrode in the instrument body, and allows free selection of an appropriate electrode for each use. The measuring instrument 1 has an instrument body 20 and a measuring electrode 10 releasably connected to the instrument body 20. Storage means 15 for storing information regarding the measuring electrode 10 in the measuring electrode 10, or in a cable 12 or a connector 13 for connecting the measuring electrode 10 to the instrument body 20.