Tolerance is introduced - standard thermocouple wire stability Shanghai dragon instrument electric appliance co. , LTD

The stability of the thermocouple test is: will the thermocouple in the annealing furnace, under the rule of temperature to stop two annealing, take out after annealing for the first time, under the rule of the temperature measurement of the thermoelectric potential for E, and then in the annealing furnace, annealing for the second time according to the above method, comes out, at the same rule to measure the temperature point thermoelectric potential for E. Thermoelectric potential measurement by the following two annealing (the difference between the E beginning - E end) For the stability of the thermocouple, should fit the specification tolerance table of thermocouple wire stability request. Stability is an important index of weighing the thermocouple performance, this paper introduced thermocouple stability concept, analyze the main causes which influence the stability of thermocouple, sharing test the stability of the thermocouple method and detailed request. Thermocouple stability is to point to in a certain temperature, thermocouple thermoelectric properties change with time and different using conditions and attack. Under the condition of the rules, the thermoelectric properties that indicate the poor stability, large change changes little, indicating good stability. The stability of the thermocouple is good or bad will directly affect the precision of the thermocouple measurement, therefore, the stability is an important index of weighing the thermocouple performance. The main factors which influence the stability of thermocouple, the high temperature environment, all kinds of harmful medium tarnish and corrosion of heat electrode; Hot electrode used in high temperature conditions, oxidation and volatilization would attack. Hot electrode under the condition of high temperature for a long time, may attack recrystallization phenomenon, causes thermal embrittlement electrode; Local hot electrodes in neutron radiation conditions, the changes of composition; Thermocouple by external force attack deformation will produce stress change of thermoelectric properties. Verification regulation rules seriously in the production of standard thermocouple to stop stability testing.