Thermocouple connectors hav developed for retaining an original accuracy of the thermocouple by minimizing EMF eror that may arise at the connnection mainly due to ambient and different thermal conductivity of each thermocouple leg the resultant temperature difference between positive and negative leg connections.
Many alternative types of terminal head are available to meet the requirements of various applications. Variations exist in size, material, accommodation, resistance to media, resistance to fire or even explosion and in other parameters.
Installing temperature sensor assemblies into thermowells or directly into the process requires the use of some kind of brass or stainless steel fitting. Fittings include various threaded unions, bayonet caps (and adapters) and flanges.
Thermocouple are widely used for temperature measurements of various gases and liquids. It bare thermoelement wires are exposed directly to detrimental atmospheres and fluid, they are often physically and chemically affected resulting in reducing service life with severe deteriorstion and corrosion.
Sheath materials range from mild and stainless steels to refractory oxides (ceramics, so called) and a variety of exotic materials including rare metals. The choice of sheath must take account of operating temperature, media haracteristics, durability and other considerations including the material relationship to the type of sensor.