Причини за обхващане на винтови термодвойки

Screw thermocouples are usually composed of temperature sensing elements, mounting fixtures, and junction boxes{{0}} They are assembled thermocouples produced in accordance with IEC standards. At the same time, the series and model spectrum of the thermocouples uniformly designed by the Ministry of Machinery and Electronics Industry are adopted. It може директно да измерва повърхностната температура на течност, пара, газообразна среда и твърда в диапазона от 0 градуса до 400 градуса в различни производствени процеси .
Embrittlement is the most common factor in the scrapping of screw thermocouples. The thermocouples are embrittled due to contamination, grain growth, redox reactions, and long-term recrystallization at high temperatures. The thermocouples are used in atomic reactors and are bombarded by neutrons. Some elements in them are transformed into other elements, changing the composition of the thermocouples. For example, the rhodium of the armored platinum-rhodium thermocouple will be transformed into palladium, and a small amount of platinum will first become gold and then mercury, which will change the thermoelectric properties and reduce the thermoelectric potential. Some cheap metal thermocouples, such as iron, nickel-chromium, and nickel-aluminum (silicon), do not undergo obvious neutron radiation transmutation. However, copper undergoes a large change in composition due to transmutation under radiation. Therefore, in the presence of neutron radiation, it is more appropriate to use nickel-chromium-nickel-aluminum thermocouples, and nickel-chromium-silicon-nickel-silicon (N-тип) Термодвойките са по-добри .
По време на процеса на измерване винтовата термодвойка ще причини нестабилност в резултатите от измерването поради условията на измерване и ограниченията на околната среда. Например: замърсяване, окисляване, редукция, физически условия, крехко напукване и облъчване са основните източници на нестабилност в резултатите от измерването на термодвойката.