Abstract: Interference detector and methods for detecting interference in a signal are described. More specifically, in one aspect, a method for detecting interference in a signal is provided. The method comprises determining whether the signal has at least one of a time and a frequency characteristic that is outside a predefined range, and determining that an interference event has been detected if the signal has at least one of such characteristics.

Abstract: Interference detector and methods for detecting interference in a signal are described. More specifically, in one aspect, a method for detecting interference in a signal is provided. The method comprises determining whether the signal has at least one of a time and a frequency characteristic that is outside a predefined range, and determining that an interference event has been detected if the signal has at least one of such characteristics.

Abstract: A fuel cell assembly includes a fuel cell, a fuel cell housing, and a diaphragm. The fuel cell housing includes an endwall and an inlet port extending through said endwall. The inlet port is for admitting a breath sample into the housing. The diaphragm is coupled within the housing such that a cavity is defined between the housing and the diaphragm. The fuel cell is positioned within the cavity and is substantially concentrically aligned with respect to the inlet port.

Abstract: A breath tester housing assembly is provided. The assembly comprises a housing having a base to be gripped by an operator, a display oriented to be in line with an operator's direct line of view while gripping the base, and a mouthpiece interface for interfacing with a removable mouthpiece so that when a subject blows into the mouthpiece, the display is not in the direct line of view of the subject. The assembly further comprises a mouthpiece for engaging to the mouthpiece interface. The mouthpiece comprises a body having a substantially planar surface.

Abstract: Interference detector and methods for detecting interference in a signal are described. More specifically, in one aspect, a method for detecting interference in a signal is provided. The method comprises determining whether the signal has at least one of a time and a frequency characteristic that is outside a predefined range, and determining that an interference event has been detected if the signal has at least one of such characteristics.

Abstract: A fuel cell assembly includes a fuel cell, a fuel cell housing, and a diaphragm. The fuel cell housing includes an endwall and an inlet port extending through said endwall. The inlet port is for admitting a breath sample into the housing. The diaphragm is coupled within the housing such that a cavity is defined between the housing and the diaphragm. The fuel cell is positioned within the cavity and is substantially concentrically aligned with respect to the inlet port.

Abstract: A method and infrared sensing device for determining the concentration of alveolar alcohol in a breath sample exhaled by a subject into an infrared sensing device. The presence of alcohol from the upper respiratory tract of the subject is detected by continuously monitoring alcohol and carbon dioxide, normalizing alcohol values with respect to carbon dioxide, calculating a difference between normalized alcohol concentration and carbon dioxide concentration over time, integrating (summing) the difference, and comparing the integrated difference with a threshold. This technique accurately and consistently detects the presence of mouth alcohol in the sample before the presence of carbon dioxide which originates in deep lung breath.

Abstract: A bottle charged with a gaseous material intended to be discharged through a range of temperatures but not outside that range, has a valve through which the gaseous material is to be directed. The valve has at least a part wholly inside the bottle, which part has a restricted port through it through which the gaseous material passes to issue from the valve, and a thermally responsive member adapted to block the port when the temperature of the interior of the bottle is outside the range. Preferably, the gaseous material is both introduced to the bottle and discharged from the bottle through the same valve, and the valve has a fill port of larger diameter than the restricted port, and an axially moveable actuating element, and the thermally responsive member is carried by the actuating element.

Abstract: A bottle charged with a gaseous material intended to be discharged through a range of temperatures but not outside that range, has a valve through which the gaseous material is to be directed. The valve has at least a part wholly inside the bottle, which part has a restricted port through it through which the gaseous material passes to issue from the valve, and a thermally responsive member adapted to block the port when the temperature of the interior of the bottle is outside the range. Preferably, the gaseous material is both introduced to the bottle and discharged from the bottle through the same valve, and the valve has a fill port of larger diameter than the restricted port, and an axially moveable actuating element, and the thermally responsive member is carried by the actuating element.

Abstract: A system and method for checking the calibration of a breath alcohol measuring instrument by the use of alcohol standards all containing substantially identical concentrations of alcohol and the use of a calculator which generates an expected measured value for the standard based on the known alcohol concentration and current atmospheric pressure.

Abstract: A method and apparatus for measuring the concentration of breath alcohol or other reactants is provided in which a breath sample is introduced to a fuel cell, wherein the number of electrons from the fuel cell resulting from oxidation of the alcohol in the breath rises to a peak and thereafter falls to a substantially steady minimum base to form a curve. The present method is based on the discovery that this curve, regardless of reactant concentration or age of fuel cell, is a log-normal distribution curve.

Abstract: A method and infrared sensing device for determining the concentration of alveolar alcohol in a breath sample exhaled by a subject into an infrared sensing device. The presence of alcohol from the upper respiratory tract of the subject is detected by continuously monitoring alcohol and carbon dioxide, normalizing alcohol values with respect to carbon dioxide, calculating a difference between normalized alcohol concentration and carbon dioxide concentration over time, integrating (summing) the difference, and comparing the integrated difference with a threshold. This technique accurately and consistently detects the presence of mouth alcohol in the sample before the presence of carbon dioxide which originates in deep lung breath.

Abstract: A method of discriminating alcohols different from ethanol in breath samples includes sampling voltages from a fuel cell at a rapid rate to establish a curve rising, upon introduction of a sample containing a known amount of ethanol without interferants, from an initial base line to a peak; determining a peak voltage; establishing an end point; determining the area under the curve from the introduction of the sample to the end point, and determing at least two other areas under the curve between the peak and the end point, a peak area, between the peak and a point on the curve relatively near the peak, and a trail area, between the end point and a point nearer the end point than the peak area; introducing to the fuel cell a breath sample that may contain an interferant in the form of an alcohol different from ethanol, and determining the peak voltage, end point, total area, peak area and trail area using the same criteria as were used in determining those pieces of information in connection with the sample co

Abstract: In a portable breath alcohol detector using a standard tubular mouthpiece, a breath direction and continuity sensor takes the form of a whistle mounted at a predetermined distance from the discharge end of the mouthpiece to leave a gap, open to the ambient atmosphere, between the discharge end and the whistle, the whistle being of sufficient sensitivity to be activated by a breath blown toward the whistle across the gap and the gap being of a size not appreciably to restrict the flow of breath, and permit air being inhaled to pass freely, whereby if the subject stops breathing, or inhales, the whistle stops sounding, and whereby residual alcohol in the whistle will not be drawn back into the mouthpiece when the subject inhales.