Measurement Method of Gas Thermocouple

The thermal response time of the gas thermocouple is more complicated. Different experimental conditions have different measurement results because it is affected by the heat exchange rate of the thermocouple and the surrounding medium, and the heat response time is short. In order to make the thermal response time of the thermocouple product, national standards: The thermal response time should be carried out on a special water flow test device. The water flow rate of the device should be maintained by 0.4 ± 0.05 m / s, and the initial temperature is in the range of 5-45 ° C, and the temperature elongation is 40-50 ° C. During the test, the temperature change of water should not be more than ± 1% of the temperature elongation. The depth depth of the trial thermocouple is 150 mm or the designed depth (select a smaller value and indicate in the test report).
Since this device is more complicated, only a few units have such a device, so the national standard provides that the manufacturer is allowed to negotiate with users, and other test methods can be used, but the data must be indicated.
Since the thermocouples in the T-type thermocouple are small near room temperature, the thermal response time is not easy to measure, so the national standard may replace its own thermoelectric electrode assembly using the thermocode assembly of the S-type thermocouple of the same specification, and then test.

When the test, the output of the thermocouple should be recorded to the time T0.5 corresponding to the temperature step by 50%, if necessary, can record 10% thermal response time T0.1 and the temperature of 90% of the thermal response time T0.9. The thermal response time recorded should be the average value of at least three test results. Each measurement result should be within ± 10% of the deviation of the average. In addition, the time required to form a temperature step change should not exceed one tenth of T0.5 of the tested thermocouple. Recording the response time of the instrument or instrument should not exceed one tenth of T0.5 of the trial thermocouple.