Abstract: A method of preparing samples for testing explosive and drug detectors of the type that search for particles in air. A liquid containing the substance of interest is placed on a flexible Teflon® surface and allowed to dry, then the Teflon® surface is rubbed onto an item that is to be tested for the presence of the substance of interest. The particles of the substance of interest are transferred to the item but are readily picked up by an air stream or other sampling device and carried into the detector.

Abstract: A method and an apparatus for producing a gas containing metal particles are described, by which the metal particles can be generated quite easily in a state similar to that in real use. Also, a method and an apparatus for evaluating a particle counter or a particle trapper by using the gas containing metal particles are described, in which the evaluation is performed under the conditions similar to those in real use. The gas containing metal particles is produced by conducting a carrier gas through a hollow metal tube and simultaneously heating the hollow metal tube to produce metal particles by vaporization effect. The pressure and the flow rate of the carrier gas and the heating amount can be controlled to produce metal particles having a required size distribution and a required concentration.

Abstract: A disposable receptacle unit for solutions is described, in particular for solutions used in calibrating sensors for measurement of physiologically relevant parameters. The receptacle is a disposable blister pack for a single use that includes several chambers to hold solutions. Each chamber is connected to a sample channel by an outlet channel sealed by a sealing element. The sensors for measurement of physiological parameters are preferably part of the receptacle unit. To calibrate the sensors, the calibration solutions in the chambers are metered into the sample channel after opening the corresponding sealing elements. After the treatment, the receptacle unit is discarded together with the sensors.

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: The present invention is an improved automated flow through electrode liquid monitoring system. The automated system has a sample inlet to a sample pump, a sample outlet from the sample pump to at least one flow through electrode with a waste port. At least one computer controls the sample pump and records data from the at least one flow through electrode for a liquid sample. The improvement relies upon (a) at least one source of a calibration sample connected to (b) an injection valve connected to said sample outlet and connected to said source, said injection valve further connected to said at least one flow through electrode, wherein said injection valve is controlled by said computer to select between said liquid sample or said calibration sample. Advantages include improved accuracy because of more frequent calibrations, no additional labor for calibration, no need to remove the flow through electrode(s), and minimal interruption of sampling.

Abstract: A vapor sensing device that is sufficiently small and lightweight to be handheld, and also modular so as to allow the device to be conveniently adapted for use in sensing the presence and concentration of a wide variety of specified vapors. The device provides these benefits using a sensor module that incorporates a sample chamber and a plurality of sensors located on a chip releasably carried within or adjacent to the sample chamber. Optionally, the sensor module can be configured to be releasably plugged into a receptacle formed in the device. Vapors are directed to pass through the sample chamber, whereupon the sensors provide a distinct combination of electrical signals in response to each. The sensors of the sensor module can take the form of chemically sensitive resistors having resistances that vary according to the identity and concentration of an adjacent vapor.

Abstract: A method is provided for stabilizing a low-concentration standard reference gas. The stabilizing method includes the steps of treating an inner wall surface of a container with high-purity water for causing the inner wall surface to adsorb the high-purity water, and charging the container with the standard reference gas.

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: 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 convenient apparatus and method for inserting surrogate metal-entraining aerosols into exhaust stacks for the purpose of realistic dynamic testing of an emissions monitor. The aerosols contain elements required to be detected by the monitor. The 14 metals regulated by the EPA as hazardous air pollutants are of particular interest. The method requires less time and fewer skilled technicians than conventional testing methods. In a preferred embodiment of the present invention, a burner (e.g., propane or kerosene) is combined with a combustion chamber, a fan, an air compressor, at least one peristaltic pump, at least one surrogate reservoir, and the necessary ductwork for connection to an exhaust stack. The amount of surrogate aerosol to be introduced to the stack is adjusted at the peristaltic pump. After heating by the burner and subsequent introduction into the hot stack, the surrogate homogeneously mixes with the exhaust stream and is presented to the sensor as a dry gas component of the exhaust stream.

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 calibration standard for calibrating a thermal gradient spectrometer. The calibration standard is a structure having a particular glucose concentration which a thermal gradient spectrometer reads for determining whether the spectrometer is in calibration. The structure of the calibration standard properly mimics the physiology of human tissue. A number of such standards, each containing a different concentration of glucose are provided in kit form with a thermal gradient spectrometer for use in calibrating the spectrometer. The spectrometer is provided with a display and internal circuitry for performing self-calibrating adjustments and a communications port for electronically coupling to a remote computer and database for supplying external calibration commands to said spectrometer.