High-Temperature Sensors

Dusty atmospheres may distort a return signal to the sensor High temperature of materials can change the speed of signals Sloped surfaces like ladders, material build-up, weld seams may cause indirect reflection leading to weak and/or split echoes... 

Abstract An Eddy current method applying a High Temperature Superconductor ( HTS ) DC SQUID sensor operating at Uquid nitrogen temperature (77K) is presented. The method is developed for the detection of surface or surface near defects. We compare the performance of the SQUID system with the performance gained from a commercial Eddy current system, while using identical probes. The experimental data are obtained on defects in gas turbine blades. The advantage of planar conformable probes for the use with the SQUID is discussed. 

Lead sulfide is used in photoconductive cells, infrared detectors, transistors, humidity sensors in rockets, catalysts for removing mercaptans from petroleum distillates, mirror coatings to limit reflectivity, high temperature solid-film lubricants, and in blue lead pigments (82). 

Install high temperature sensors interlocked to shut down reactor... 

The primary protection for high temperature, which could lower the maximum allowable working pressure below the PSV setting, is a high-temperature sensor (TSH), which shuts in the inlet or the source of heat. Back-up protection is provided by leak detection devices. 

High temperature sensors are applicable only to vessels having a... 

Temperature High Temperature Sensor Temperature Safety High 0 ... 

An interlock system (sensors and valves) which isolates offgas flow to die process heater firebox and routes the offgas to atmosphere on detection of low nitrogen flow or high temperature at the detonation flame arrester outlet. 

Figure 4-230 shows the photograph of a Develco high-temperature directional sensor. For all the sensor packages, calibration data taken at 25, 75, 125, 150, 175 and 200°C are provided. Computer modeling coefficients provide sensor accuracy of 0.001 G and 0.1° alignment from 0 to 175°C. From 175 to 200°C the sensor accuracy is 0.003 G and 0.1° alignment. 

Figure 4-230. Photograph of a high-temperature directional sensor with three accelerometers and three magnetometers. (Courtesy Develco [103].j...

The stability of ceramic materials at high temperatures has made them useful as furnace liners and has led to interest in ceramic automobile engines, which could endure overheating. Currently, a typical automobile contains about 35 kg of ceramic materials such as spark plugs, pressure and vibration sensors, brake linings, catalytic converters, and thermal and electrical insulation. Some fuel cells make use of a porous solid electrolyte such as zirconia, Zr02, that contains a small amount of calcium oxide. It is an electronic insulator, and so electrons do not flow through it, but oxide ions do. 

O2, and hydrocarbons, leading to a NH3 selective sensor. Arguments in favor of using a zeolite-based sensor in NH3 detection for automotive apphcations are low cost, high temperature stability, and suitability for use in thick-film technology, of common use in the automotive industry [72]. The sensors were tested on an engine test bank and the authors claim that the sensor itself meets aU the technological and economical demands of the automotive industry [73]. 

The added value, variety of use, and methods to apply zeohte coatings or films in sensor apphcations has been convincingly demonstrated. Although current trends focus on miniaturization of sensors and creating smaUer zeohte crystals and thinner films, to decrease the response time of the sensor [79], often thick-film technology is sufficient to apply zeohte films for this type of application. Some sensor materials cannot withstand the high temperatures necessary for template removal by air calcination. Recent work demonstrated that ozonication yields... 

The coalescence of Au microcrystal in the islet film occurs during thermal annealing, as well as when the metal concentration is increased. It is probably the coalescence that does determine the above-mentioned loss of Au/ZnO-sensor sensitivity during high-temperature heating operations. 

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