Magnesium Oxide (MgO) thermocouples consists of a thermocouple junction encased in a metal sheath, surrounded by compressed magnesium oxide insulation. The thermocouple junction, also known as the sensing junction, is the point where the two dissimilar metals meet and are usually welded together. Since the sensing junction is sealed from the environment, there is reduced potential for contamination and corrosion. MgO thermocouple sheaths are annealed and can be formed into different shapes and diameters.
Industrial thermocouple usually are constructed by inserting the thermocouple element into a metallic thermowell or ceramic protection tube. Not only does this protect the sensing element from the process, it accommodates easy removal and replacement. Industrial thermocouples can be designed with virtually endless combinations of elements, wells, protection tubes, junction boxes, wiring terminals, and process connections.