The principle and types of thermocouple temperature measurement _ instrument

Thermocouple is a kind of thermocouple, people often use the application range is very wide, many in the industry are in the application of thermocouple. Thermocouple temperature measurement principle is to put the two different material a conductor or semi-conductor a and b welding together, constitute a closed loop, when the conductor a and b two persistent point temperature difference between 1 and 2, occurs between the electromotive force, and thus form the size of a current in the circuit, this kind of phenomenon called the thermoelectric effect. Thermocouple is in using this effect to work. Thermocouple unique special advantage mainly table now has a smaller thermal capacity and its compact structure closely, big and small, small thermal inertia, the temperature to be measured response quickly, small time constant, with satisfactory mechanical properties, resistance to vibration and shock. Thermocouples are inserted into the casing, casing heat transfer effect of the temperature survey precision. In the experimental process on the temperature measurement should be as likely to use a finer thermowell. Casing installed position also of things to think about problem of thermal conductivity. When measuring the temperature of the pipe should be as possible in the pipe bend, and to in enough depth. If there is no corner can use, is in oblique. Line very carefully part should be bold and then inclined plug, to meet air flow direction in them, and make the temperature sensing element head in core pipe line. Thermowells exposed local should keep warm, prevent heat dissipation. Thermocouple types commonly used thermocouple could be divided into two types: standard thermocouple and non-standard thermocouple. Using standard thermocouple refers to the national standard specifies its thermoelectric potential and the relationship between temperature, permissible error, and a unified standard score table of thermocouple, it has the matched digital display table to choose from. Non-standard thermocouple or on the order of magnitude less than the range using standardized thermocouple, generally no unified indexing table, mainly used for the measurement of some special occasions.