B type thermocouple is a kind of common measuring instruments, the scope of application is very extensive. At the time of thermocouple temperature measurement in fact, there are two conditions are necessary, for the thermocouple temperature measurement is very important. B type thermocouple is a temperature sensing element, is a kind of an instrument, thermocouple temperature measurement directly. By platinum and rhodium two different components of conductor material closed loop, because material is different, different electron diffusion of electron density, stable equilibrium is produced after electric potential. When temperature gradient is at both ends, the loop will be current, produce thermoelectric emfs, the bigger the temperature difference, the greater the current will be. To know the temperature after the measured thermoelectric emfs. Thermocouple in practice is a kind of energy converter, convert heat energy into electricity. B type thermocouple wide technical advantage of thermocouple temperature measurement range, stable performance compare; High measurement accuracy, thermocouple direct contact with the object being measured, not affected by the intermediate medium; Thermal response time is fast, flexible thermocouple response to temperature changes; Wide measurement range, the thermocouple 40 ℃ ~ + 1600 ℃ can be continuous temperature measurement; Thermocouple performance is stable, good mechanical strength.