Measurement of response time of K-type thermocouple wire

The thermal response time of K-type thermocouple wires is actually quite complex, and different test conditions will produce different measurement results. This is due to the influence of the heat transfer rate of the surrounding medium. If the heat transfer rate is high, the thermal response time will be shorter.
In order to make the thermal response time of thermocouples comparable, the national standard stipulates that the thermal response time should be conducted on a dedicated water flow test device. The water flow velocity of the device should be maintained at 0.4 ± 0.05m/s, with an initial temperature range of 5-45 ℃ and a temperature step value of 40-50 ℃. During the experiment, the temperature change of water should not exceed ± 1% of the temperature step value. The insertion depth of the thermocouple for the subjects is 150mm or the designed insertion depth.
Due to the small thermoelectric potential of thermocouples near room temperature and the difficulty in measuring their thermal response time, national standards stipulate that K-type thermocouple wires of the same specifications can be used to replace their own thermoelectric electrode components, and then tested.
During the experiment, the time T0.5 for the output change of the thermocouple to reach 50% of the temperature step change should be recorded. If necessary, the thermal response time T0.1 for a 10% change and T0.9 for a 90% change can be recorded. The recorded thermal response time should be the average of at least three test results of the same experiment, and the deviation of each measurement result from the average should be within ± 10%. In addition, the time required to form a temperature step change should not exceed one tenth of T0.5 of the tested thermocouple. The response time of recording instruments or meters should not exceed one tenth of T0.5 of the tested thermocouple.