The thermocouple is used correctly in the four areas that need attention
Thermocouples are the most accurate and most economical product in the development of measuring sensors, so it has become the most widely used type in the use of temperature measurement components. It measures temperature directly and converts temperature signals into thermoelectromotive force signals , Through the electrical instrument (secondary instrument) into the measured medium temperature.
In order to improve the measurement accuracy, reduce the measurement error and prolong the service life of the thermocouple, the user should not only have the instrument operation skills, but also have the physical, chemical and material knowledge. The author based on years of practice, and see the relevant information, here in a more detailed description of the thermocouple measurement error and its precautions. In the use of thermocouple process, should focus on the following issues:
1, thermocouple degree of division must be used with the temperature measurement and control instruments required by the thermocouple consistent;
2, the installation of the location of the thermocouple should be as far as possible away from the strong electromagnetic field, to avoid high-power power cord, so as not to introduce additional interference signal thermometer; 3, a reasonable choice of thermocouple casing material, diameter, Strength, and to adapt to the measured atmosphere. The outer casing surface should be kept clean, the surface stains will increase the thermal resistance, the measured temperature will be lower than the actual temperature;
3, thermocouple can not work for a long time in the maximum allowable temperature, otherwise it will cause changes in thermocouple material, resulting in increased measurement error. In the measurement of low temperature, in order to reduce the thermal inertia of the thermocouple, can be used under the type or outcrop thermocouple;
4, should always check the electrode and outer casing is intact, if found to reduce the local diameter or casing casing surface corrosion and other phenomena, should stop using, and replace the new thermocouple. After the thermocouple is damaged, the damaged end can be removed, or the measurement end and the reference side of the swap, re-welding, after calibration can continue to use.
