With the development of science and technology, the degree and difficulty of distinguishing true and false products are constantly increasing. How can we buy suitable and qualified temperature sensor products when we purchase thermocouples? In fact, there are many ways and methods to identify thermocouples, and each method has its own characteristics. When we choose thermocouples, we usually test them on the spot or use a multimeter for testing. Let's take a look at the specific method of using a multimeter for testing.
Multimeter testing: Before using a multimeter for testing, we first observe with the naked eye whether the protective tube is corroded, penetrated, or leaking. Then use a multimeter to measure the continuity. The resistance of the assembled thermocouple is generally not greater than 2 ohms, and the resistance of the network cable is generally not greater than 50 ohms. Generally, if it is greater than 1K, it can be determined that it is broken. Important reminder: 1. The above is only a simple judgment of thermocouples and explosion-proof thermocouples. Long term operation in high temperature environments can easily cause temperature drift. For example, K-type long-term operation above 1000 degrees, E-type long-term operation above 800 degrees, and S-type long-term operation above 1250 degrees will cause drift. Drifting of 2-5 degrees at 1000 degrees is very common. According to relevant technical regulations, it is a mandatory standard measuring instrument for calibration, involving energy conservation and safety production. Generally, it is required to be sent to the flowmeter measurement and testing center for calibration after one year of use.

Measure the resistance value with a multimeter A resistance exceeding 100K is considered faulty Use a multimeter ohmmeter to measure the thermocouple, adjust the resistance, connect both ends, and use a lighter to slightly heat it. If the multimeter pointer significantly increases or decreases, it indicates that it is good. If the pointer does not move, it indicates that it is already broken. You can use a multimeter to measure the voltage at both ends in millivolt range. If there is no voltage, it will malfunction.