How does the response time of the K-type thermocouple be measured?
Understand the response time of K-type thermocouple how to measure?
I believe that everyone in the operation of the use of K-type thermocouple in the process will find K-type thermocouple response time for the entire measurement process is very important, then the K-type thermocouple response time should be how to measure it?
K-type thermocouple measurement of high precision, wide measurement range. Due to the thermocouple directly with the measured object contact, from the middle of the medium.
K-type thermocouple structure is simple, easy to use. Thermocouples are usually composed of two different wires, and are not limited by the size and the beginning, the outer protective sleeve, with very convenient to use.
Measuring the K-type thermocouple thermal response time is actually more complex, different test conditions will produce different measurement results, which is due to the surrounding medium heat transfer rate, high heat transfer rate, the thermal response time is short The
In order to make the thermal response time of the thermocouple comparable, the national standard stipulates that the thermal response time should be carried out on a dedicated water flow test device. The water velocity of the device should be maintained at 0.4 ± 0.05 m / s, the initial temperature is in the range of 5-45 ° C, and the temperature step value is 40-50 ° C. During the test, the temperature of the water should not be greater than ± 1% of the temperature step value. The implanted thermocouple has a depth of 150 mm or a depth of implantation.
In the thermocouple near the room temperature thermoelectric power is very small, the thermal response time is not easy to measure, so the national standard can be used with the specifications of the K-type thermocouple thermocouple assembly to replace its own thermal electrode assembly, and then test.
The test should record the output of the thermocouple to a time T0.5 corresponding to 50% of the temperature step change. If necessary, record the thermal response time T0.1 of 10% and the thermal response time T0.9 of 90% change.
The recorded thermal response time shall be the average of the results of at least three tests of the same test, and the deviation of each measurement result for the mean should be within ± 10%.
In addition, the time required to form a temperature step change should not exceed one tenth of the T0.5 of the thermocouple under test. The response time of the instrument or instrument should not exceed one tenth of the T0.5 of the thermocouple.
