Abstract: A thermal conductivity detector includes separate sample gas and reference gas chambers. Each chamber has a gas inlet and a gas outlet and a sensor. The chambers are connected by at least one passageway. For example, a passageway can extend from the sample gas chamber to the reference gas chamber adjacent the gas inlets. As a further example, a passageway can be provided adjacent the gas outlets. More specifically, an exhaust passageway extends from the first passageway to the additional passageway and there is an exhaust outlet connected to the additional passageway.

Abstract: A method and apparatus for sensing a flammable vapor are described herein. Initially, a first thermal conductivity of a vapor at a first temperature and a second thermal conductivity of the vapor at a second temperature can be determined. Thereafter, a ratio of the first thermal conductivity signal to that of the second thermal conductivity can be calculated to obtain a primary “vapor” signal. The “vapor” ratio can then be compared to an “air” ratio of air without the vapor at the first temperature and the second temperature to obtain a secondary signal thereof. Such a secondary signal can then be compared to an alarm set-point value to thereby determine whether the vapor comprises a flammable vapor and a risk-reducing action thereof be taken.

Abstract: A thermal conductivity detector with an electrically heatable heating filament (6) that is mounted in the middle of a channel (5) in such a way that a fluid can flow around it. The heating filament is carried on its two ends on two electrically conductive carriers (7, 8) that intersect this channel. In particular to prevent the heating filament from relaxing at operational temperatures, at least one of the two carriers (7, 8) is embodied in such a way that its distance from the other carrier is greater in the region of the middle of the channel than in the region of the wall of the channel (9). As a result, as the temperature rises, the middle areas of the two carriers (7, 8) on which the heating filament (6) is held move away from each other, so that the heating filament (6) is tightened.

Abstract: A focusing device for volatile and semi-volatile organic compounds in the gaseous phase, comprising a support structure, a container for said organic compounds, a cooling element and a heating element for their transfer to the analysis system, characterized in that said cooling element and said heating element are positioned in two separate regions of said support structure and form a single block movable relative to said container.

Abstract: A method and apparatus for determining the effective composition of a mixture of gases including a plurality of hydrocarbon gases, the method comprising selecting one or more effective hydrocarbons to represent the plurality of hydrocarbon gases in the gas mixture, the number of effective hydrocarbons being less than the number of hydrocarbon gases in the gas mixture whose composition is to be determined; measuring a number of characteristics of the gas mixture whose effective composition is to be determined, the number of characteristics to be measured being one less than the total number of components to be determined and determining the effective composition of the mixture of gases from the measurements of the characteristics of the gas mixture, a predetermined parameter dependent upon the characteristic measured and knowing that the sum of the components of the gas mixture equals 100%.

Abstract: A thermal conductivity detector includes separate sample gas and reference gas chambers. Each chamber has a gas inlet and a gas outlet and a sensor. The chambers are connected by at least one passageway. For example, a passageway can extend from the sample gas chamber to the reference gas chamber adjacent the gas inlets. As a further example, a passageway can be provided adjacent the gas outlets. More specifically, an exhaust passageway extends from the first passageway to the additional passageway and there is an exhaust outlet connected to the additional passageway.

Abstract: A micro fluid analyzer having a concentrator and separator. A strip continuous through a channel in the concentrator may provide a hot zone that may move with the flow of fluid through the channel of the concentrator to provide a concentration of heat in the flow. A pump may provide a flow to the fluid through the analyzer. Detectors may be positioned at places where the fluid may flow. A processor or controller may be connected to the strip, separator, pump and detectors. The concentrator, separator, detectors and processor may be integrated on one chip.

Abstract: In a gas chromatograph an injected sample for analysis is led through a separating device to separate components contained in the sample, at the end of which selected components are detected by means of a detector and quantitatively determined by means of the detector signal. A validation and furthermore an improvement in accuracy of the analysis is possible, whereby the sample (3) is non-destructively analysed by a further detector (16), before the separation device (5) and quantitatively determined with the further detector signal (17) delivered by the further detector (16) and the result of the quantitative determination of the sample (3) taken for monitoring the analysis.

Abstract: A gas chromatograph in which the substances of a substance mixture that is to be analyzed are separated in a separation device and are detected in a detector device. An evaluation device (10) provides a result (11) in the form of a quantitative determination of given substances depending on the detector signals. To obtain a relatively rapid analysis result, an additional detector device (13), which generates additional detector signals (16) based on the substances that at this stage have not been completely separated, is located in the path of the separation device (6). A computational unit (18) provides a quantitative determination of at least one part of the given substances as a further result (20), based on the additional detector signals (16). This somewhat imprecise but rapid result can be used for rapid control or regulatory interventions in a process (4).

Abstract: A highly compact measuring gas cell for a device for measuring the concentration of a paramagnetic gas on the basis of the change in the thermal conductivity of the paramagnetic gas, which is brought about by a change in the magnetic field. The measuring gas cell has a bottom plate (1) that carries a measuring element (1.4) for the detection of the thermal conductivity of the measured gas, electric leads, an electric measuring gas cell heater (1.2) and a temperature-dependent electric sensor element (1.3) for the detection of the temperature of the measuring gas cell. A channel plate (2) is cut out for the gas guide in the area of the measuring element (1.4) and around the measuring element (1.4). A cover plate (3), seals the measuring gas cell in the upward direction and has at least two holes for the inlet and outlet of the gas into and out of the gas guide of the channel plate (2).

Abstract: A measuring head for the determination of the concentration of a paramagnetic gas in a gas sample has first and second housing parts (21, 2) made of a steel alloy for accommodating a magnet coil body (4, 5) each. The magnet coil bodies extend concentrically around the central axis of each housing part (21, 2). Metallic bars (31, 3), which are used as magnet poles for the measuring head, are located at spaced locations with a defined air gap in the assembled state of the measuring head. The bars are arranged in the center of the measuring head in the area of the central axis of the housing parts (21, 2). A sample gas cuvette support (6) is provided in the air gap between the housing parts (21, 2) for positioning a sample gas cuvette holder (1). The sample gas cuvette support (6) is provided with a gas inlet and gas outlet (8, 81).

Abstract: A gas sensor for detection of oxidizing and reducing gases, including O2, CO2, CO, and H2, monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

Abstract: The invention is directed to a method of determining gas concentrations in a gas mixture comprising more than one component, in which thermal conductivities of the gas mixture are determined at different temperatures, deriving therefrom the individual gas concentrations. The invention aims to improve upon this method by enabling the accuracy of measurement to be enhanced, the sensitivity to external influences to be diminished, and the constructional expenditure of a measuring apparatus to be reduced.

Abstract: Fluid leak detection through thermal sensing is disclosed. A sensor includes one or more flexible, thermally conductive, fluid isolating layers, and a thermally sensitive detector situated within the flexible, thermally conductive, fluid isolating layers. The detector is responsive to a temperature change resulting from leaking fluid coming in contact with the sensor. The sensor may also including an affixing mechanism, such as glue, on the isolating layers, to affix the sensor to a potential fluid leak source, such as a tank or a piping line. The sensor may further include connectors located at its ends. The detector may be a thermally sensitive resistor, such as platinum or nickel, and the, fluid isolating layers may be capton.

Abstract: A gas sensor for detection of oxidizing and reducing gases, including O2, CO2, CO, and H2, monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

Abstract: A method and apparatus for measuring the calorific value of a gas. The apparatus includes a chamber to which a gas in question, for example natural gas, is supplied through an inlet and leaves through an outlet. The speed of sound SoS at ambient temperature is measured using any suitable method such as electronic control and a calculating device and an ultra-sound emitter and an ultra-sound receiver. The ambient temperatures Ta, is observed by a temperature sensor, and a thermal conductivity sensor measures the thermal conductivity of the gas at two different temperatures above the ambient temperature. One value ThCH, of the thermal conductivity is measured at 70° C. above ambient and the other value ThCL of the thermal conductivity is measured at 50° C. above ambient. The control calculates the calorific value CV of the gas according to the formula: CV=a·ThCH+b·ThCL+C·SoS+d·Ta+e·Ta2 +f, where a, b, c, d, e and f are constants.

Abstract: The object is to improve an apparatus for measuring the concentration of a paramagnetic gas in a gas sample, in such a way a measurement signal with a low noise ratio is obtained. The apparatus proposed according to the invention is characterized by a modulatable magnetic field source 4, 5, 6, 7 with an air gap 3 as a measuring chamber for receiving the gas sample; a modulation source 26 for outputting a modulation signal to the magnetic field source 4, 5, 6, 7; a measuring element 8, disposed inside the air gap 3 and heated to an operating temperature, for outputting a heat flow measurement signal; a filter device 28, 29, for filtering periodic fluctuations out, caused by the modulation of the magnetic field source, from the heat flow measurement signal caused by the modulation of the magnetic field source, the amplitude of the periodic fluctuations, being a measure for the proportion of the gas in the gas sample.

Abstract: A substrate covered with an insulating layer and a catalytic gate electrode 26 disposed on the insulating layer. The catalytic gate electrode 26 has a first end having a first contact pad 30 and a second end having a second contact pad 32. A meander 28 is placed between the first contact and the second contact. A third contact pad 24 is coupled to the underside of the substrate 22. The temperature is measured between the first contact pad 30 and second contact pad 32 while sensor's response to gas concentration is sensed between the gate electrode 26 and the third contact 24.

Abstract: A temperature sensor, in particular for a gas sensor, has at least one printed conductor, where a temperature-dependent change in a resistance of the printed conductor is detected and analyzed. The printed conductor has at least one section made of a solid electrolyte.

Abstract: A control circuit for a thermal conductivity cell employs a constant resistance bridge drive circuit which automatically adjusts to maintain a measurement filament at a constant resistance. A reference filament provides a differential signal representative of the concentration of an analyte. A detection circuit utilizes digital/analog methods to significantly reduce 1/f noise of an amplifier providing at least a seven fold improvement in signal-to-noise ratio. The circuit also includes a bridge nulling method adjusted under microprocessor control to eliminate manual offset adjustments. A reference protection circuit is coupled to the reference filament and prevents the voltage applied to the filaments from overheating the filaments in the event there is a breach in the gas flow path.

Abstract: The present invention relates to a quantitative measuring method of argon impurity contained in high purity oxygen by means of triple point and &ggr;-&bgr; phase transition of oxygen, and also to a cryostat employed in quantitative measuring of argon impurity contained in high purity oxygen.

Abstract: An integrated environment temperature sensor device provides improved temperature sensitivity by using a diode as the sensing element. The integrated sensor device comprises a heater element for creating a fixed quantity of heat energy. The sensor device also comprises an integrated circuit diode which receives the fixed quantity of heat energy from the heater element. The integrated circuit diode has a constant forward bias current applied thereto and a change in environment temperature is reflected in a voltage change across the integrated circuit diode. The integrated circuit diode further comprises an electrically insulating layer positioned substantially between the heater element and the integrated circuit diode for electrically insulating the two from each other.