Gas thermocouple thermal response time is more complex, different test conditions have different measurements, it is because it affected by the heat transfer rate of thermocouple with surrounding medium, heat transfer rate is high, the thermal response time is short. In order to make the thermocouple products comparable thermal response time, national standards: thermal response time should be in the special flow test device. Of flow velocity in the device should be 0.4 + / - 0.05 m/s, the initial temperature in the range of 5-45 ℃, temperature step value of 40-50 ℃. In the process of test, the water temperature should be no greater than temperature step value plus or minus 1%. Subjects in depth of thermocouple designed for 150 mm or in depth (choose smaller values and indicated in the test report).
Because the device is more complex, at present only a few units have the equipment, so the rules permit factories consultation with users in the state standards, can use other test methods, but the data must be given indicate the test conditions.
Because of B type thermocouple near room temperature thermoelectric power is small, thermal response time is not easy to measure, so can use the same specification of national standard of the S type thermocouple electrode component to replace its own hot electrode components, and then tested.
Test should record the change of the thermocouple output to the equivalent of 50% of the time temperature step change T0.5, when necessary to record 90% 10% of the thermal response time T0.1 and changes of T0.9 thermal response time. Recorded by the thermal response time, should be the same test at least three times the average of the test results, each measurement results for the average deviation should be within + / - 10%. In addition, the time needed for forming temperature step change should not be less than one over ten of the is test thermocouple T0.5. The response time of the recording instrument or instrument table should not exceed one hundred percent of the participants thermocouple T0.5.