Abstract: The invention discloses an oxygen concentration monitor using a Galvanic cell type oxygen sensor. An automatic calibration circuit always calibrates the maximum output of the sensor as the value corresponding to an oxygen concentration of 21%, based on the fact that the oxygen concentration in a fresh air never exceeds 21%.

Abstract: Deterioration detector system for catalyst in use for emission gas purifier, comprising; an emission passageway through which exhaust gas from internal combustion engine, passes by way of catalyst to facilitate the reducing and oxidizing reaction among the toxicant component of hydrocarbon, carbon monoxide and nitrogen oxide; a sensor placed at the emission passageway to position downstream of the catalyst against the exhaust gas flow so as to generate an output in direct proportion to air-fuel ratio in the exhaust gas; an annunciator arranged to activate in response to the output of more than the predetermined level generated from the air- fuel ratio sensor.

Abstract: A catalytic gas detector circuit in which the temperature of a resistance gas sensing element, contained in a bridge circuit, is reduced and therefore stabilized by energizing a transistor to draw off current from the sensing element when the sensing element is exposed to high concentrations of combustible hydrocarbon gases.

Abstract: An improved device for determining the trend of the partial pressure of a gas, such as oxygen or carbon dioxide, which diffuses outwardly through a patient's skin. The device, such as a cutaneous gas monitor, generates over time a series of partial pressure input values that are compared to one another for determining a trend in the partial pressure. This trend is communicated to the operator of the device.

Abstract: An inflammable gas detector for detecting an inflammable gas wherein the inflammable gas detector is of the platinum-alloy wire type which forms part of a resistance bridge network to operate in a condition for maximum sensitivity by preadjusting the voltage at the terminals of the inflammable gas detector in accordance with the desired type of gas to be detected, then utilizing the signals supplied by the detector in the resistance bridge network to bring the cathode of a diode to the threshold limit value and at the same time to render two further diodes conductive to activate a signal or control relay or both.

Abstract: A measuring and evaluating device and method for mine galleries and the like can monitor the various parameters of the atmosphere and normalize the parameters for display and storage in the device. In an emergency the danger-posing operations of the device are shut down although the memory is maintained and, for further safety, a detector which may pose a danger may be inactivated and replaced by a less precise detector for the same parameter but which poses no danger.

Abstract: An oxygen shortage sensor is placed in a space defined above a burner unit exposed to the atmosphere. When an oxygen shortage condition is detected by the oxygen shortage sensor, an alarm is raised from an alarm unit or combustion of the burner unit is stopped by a combustion stopper. In such an apparatus, in order to secure a stable oxygen shortage detection by the oxygen shortage sensor, the oxygen shortage sensor is located in a space above the burner unit and in a casing having an opening formed on the side of the burner unit.

Abstract: Ambiguous measurement results can be obtained in the measurement and indication of high concentrations obtained in air of combustible gases when employing the thermal effect principle. In order to prevent such ambiguities from arising, the measuring range is, in accordance with the invention, limited to the linear part of the characteristic curve of the measuring sensor and displayed digitally.

Abstract: An improved thick film stannic oxide sensor is disclosed whereby the sensitivity of the sensor to CO is enhanced by the addition of a rare earth oxide to the sensor composition and the catalytic reactivity of the sensor, when contacted by a gas containing a reducing constituent, i.e., H.sub.2 or CO, and oxygen, is enhanced by employing RuCl.sub.3 or PtCl.sub.2 as a catalyst.

Abstract: In a catalytic type propane gas or organic gas detector there is provided a heater for the catalyst of the heat pipe type. One end of the heat pipe is in the flame of the standing pilot and the other end is in contact with the catalyst so that the waste heat from the pilot flame is used to maintain the catalyst at an elevated temperature.

Abstract: A gas sensing unit designed to be protected against explosions and serving for the detection of combustible gases in an atmosphere, containing a gas sensor functioning according to the principle of catalytic oxidation or a semiconductor gas sensor. The gas sensing unit contains, within a housing, at least two mutually separated chambers or spaces. The one chambr is a compression-proof space and contains an electronic evaluation circuit for the gas sensor, the other chamber, which is a space structured to be protected against explosions, contains the gas sensor and a balancing element and is separated from the atmosphere by a sintered metal bushing or sleeve. A third explosion-proof chamber or space can be provided in the gas sensing unit for the purpose of connecting the lines or conductors. The gas sensor together with the balancing adapter forms an assembly or unit which can be pluggably arranged in the cover of the chamber containing the electronic system or hardware.

Abstract: In a gas component detector, a first gas component detecting element is formed by a metal oxide having an electric resistance depending on the concentration of gas components and on the temperature of a detected gas. A second gas component detecting element is formed by a metal oxide having the same temperature coefficient of electric resistance as that of the first gas component detecting element and having an electric resistance depending on the concentration of gas components and on the temperature of the detected gas and having a slower detection response time against the concentration of gas components in the detected gas than that of the first gas component detecting element.

Abstract: Apparatus for detecting and signalling the presence of a dangerous gas in an atmosphere comprising means for detecting the gas and means for signalling when the gas content exceeds a predetermined level. Said detecting means and said signalling means are disposed in a common housing and connecting by a double-wire cable to a separate supply.

Abstract: A sensor for the quantitative determination of reduction of a gas in which a thin tungsten oxide film detector element includes means for providing a specificity for the gas to be detected with respect to other gases. If ammonia is to be detected, a platinum catalyst is utilized. If hydrogen sulfide is to be detected, tungsten trioxide is used in the film.

Abstract: A catalytic gas detector is formed as a sandwich and comprises two flat printed film resistance thermometer sensors back-to-back with a layer of thermally insulating material between them. A coating of a suitable catalytic substance covers an exposed flat face of one of the two sensors.

Abstract: An improved gas leakage indicating device of the type in which an electrical warning signal is generated. Electrically conductive material which is chemically reactive with the particular gas to be sensed comprises part of an electric circuit. The electrically conductive material is located proximate connections or seals in the gas vessels so that in the event of a leak the gas chemically reacts with the conductor. The subsequent destruction or degradation of the conductor breaks the electric circuit, thereby generating the appropriate warning signal.

Abstract: A gas or vapor sensing and alarm device in an air purifying respirator for warning the wearer of hazardous levels of gases or vapors penetrating through the respirator cartridge. An exothermic sensor which can be fitted in the cartridge adaptor or facepiece cavity of the respirator monitors the heat evolved during adsorption of the vapor or gas into the sensor's adsorbent and triggers in alarm when the respirator cartridge has reached the end of its service life.