A gas detector includes metal-oxide semiconductor gas sensors and their driving circuit. The gas detector stores the ratio of initial gas sensor resistance in air and that in an atmosphere including Freon gas, for the gas sensors. The gas detector learns sensor resistance in air for a gas sensor in use and detects Freon gas by comparing the sensor resistance of the gas sensor in use with the learned resistance in air divided by the ratio. When the first gas sensor has been used for a predetermined period, both the first gas sensor and a second gas sensor are used for a learning period to continue detection of Freon by the first gas sensor and to learn the resistance in air of the second gas sensor. After completion of the learning period, Freon is detected by the second gas sensor.

An oxy-pyrohydrolysis article including a pyrotube and a sample insert are described. The sample insert includes a sample insert tube and a corrosion-resistant protective tube. Methods of conducting oxy-pyrohydrolysis using such articles, including their use for measuring total halogen (e.g., total fluorine) content are also described.

The present invention discloses a method and system for conducting high temperature corrosion tests on metallic alloys without the need for extensive laboratory equipment and attendant safety measures through the use of a two-compartment ampoule where a vestibule connects these two compartments. A pre-selected mixture of salts is placed in one compartment in order to generate a specific partial pressure of halogen gas; and a metallic alloy is placed in the other compartment. The ampoule is then heated to a pre-determined temperature and held at this temperature for a pre-determined time period. A halogen gas of a specific partial pressure is thereby generated from the mixture of salts which comes into contact with the metallic alloy. Because the ampoule creates a sealed environment, the metallic alloy is under constant halogenation during the pre-determined time period. The metallic alloy is removed for examination when the pre-determined time period expires.

An electrochemical chlorine gas sensor is disclosed with a working electrode, a counter electrode, and a reference electrode. The working electrode may be coated with a nanoporous gold layer, a first solution comprising an ionic liquid, and a second solution that may be selected from a Nation solution, a chitosan solution, an agar solution, or combinations thereof. The reference and counter electrodes may be further coated with the ionic liquid.

In one aspect of the present disclosure, there is provided a sensor device for sensing a fluorine-based gas, the device comprising: a substrate; and a sensing layer on the substrate, wherein the sensing layer includes hydrogenated titanium dioxide nano-particles, wherein when the sensing layer reacts with the fluorine-based gas, the sending layer has a color change.

An electrochemical chlorine gas sensor is disclosed with a working electrode, a counter electrode, and a reference electrode. The working electrode may be coated with a nanoporous gold layer, a first solution comprising an ionic liquid, and a second solution that may be selected from a Nafion solution, a chitosan solution, an agar solution, or combinations thereof. The reference and counter electrodes may be further coated with the ionic liquid.

Oxy-pyrohydrolysis articles, systems and methods for total halogen, in particular fluorine analysis are provided. A sample containing halogen elements is provided into a pyrotube for combustion. A combustion-enhancing bed including ceramic fibers or fabrics is disposed inside the pyrotube to enhance the combustion and protect the pyrotube from damage by corrosive gases.

An apparatus includes: a gas maintenance system having a gas supply system fluidly connected to one or more gas discharge chambers; a detection apparatus fluidly connected to each gas discharge chamber; and a control system connected to the gas maintenance system and the detection apparatus. The detection apparatus includes: a vessel defining a reaction cavity that houses a metal oxide and is fluidly connected to the gas discharge chamber for receiving mixed gas including fluorine from the gas discharge chamber in the reaction cavity, the vessel enabling a reaction between the fluorine of the received mixed gas and the metal oxide to form a new gas mixture including oxygen; and an oxygen sensor fluidly connected to the new gas mixture to sense an amount of oxygen within the new gas mixture. The control system is configured to estimate a concentration of fluorine in the received mixed gas.

A gas sensor for sensing a target gas, the gas sensor comprising first and second electrodes; a support layer between the first and second electrodes; and a reagent on the support layer for binding the target gas, wherein the first and second electrodes are in electrical contact with the support layer and the reagent.

A method for measuring the concentration of fluorine gas, which includes irradiating a halogen fluoride-containing gas with ultraviolet light in which the ratio (W.sub.X/W.sub.F) of the maximum value (W.sub.X) of ultraviolet light intensity in the wavelength region of less than 250 nm with respect to the ultraviolet light intensity (W.sub.F) at a wavelength of 285 nm is 1/10 or less, and measuring the absorbance at a wavelength of 285 nm to obtain the concentration of fluorine gas contained in the halogen fluoride-containing gas.