The difference between thermocouple temperature measurement and infrared temperature measurement

1. Contact temperature measurement method. The thermoelectric metal thermocouple copper-constantane (index No. T) 0-200 °C is the most accurate, high precision, low temperature sensitivity; iron - Constantan (index number J) below 100 °C linear good, there are High sensitivity.

2. Non-contact temperature measurement method. Thermal radiation energy change part of the radiation method by the photo-cell, light-sensitive resistors and other infrared detection components for the thermal components, because they have a certain spectral selectivity, so non-full-spectrum instrument due to the working band can be selected, so you can avoid the intermediate media Absorption peak.

3. Colorimetry. Comparing the ratios of the two light wave radiative energies is fast, close to the real temperature, and less affected by the intermediate medium.

In short, thermocouple temperature measurement method is relatively simple, reliable, and high measurement accuracy; but due to the need for sufficient heat exchange between the temperature measurement element and the measured medium, it takes a certain time to achieve thermal equilibrium, so there is a delay in temperature measurement, and at the same time Due to the limitations of high temperature materials, it cannot be applied to very high temperature measurements. The infrared temperature measurement method measures the temperature by the principle of thermal radiation. The temperature measurement element does not need to be in contact with the measured medium, and has a wide range of temperature measurement, is not limited by the upper limit of the temperature measurement, and does not destroy the temperature field of the measured object. The speed is generally relatively fast; however, due to the influence of external factors such as the emissivity, measurement distance, smoke, dust and moisture of the object, the measurement error is large. Infrared temperature measurement method is affected by the outside world, and cannot measure the internal temperature. In the CSA and UL standards, only thermocouples and resistance methods are specified for temperature rise tests.

The infrared temperature measurement method can quickly provide temperature measurement. With a thermocouple reading a leaky connection point, the infrared thermometer can almost read the temperature of all the connection points. In addition, because the infrared thermometer is solid, lightweight, and safe, it can safely read inaccessible or unreachable target temperatures. You can read the target temperature within the allowable range of the instrument. Infrared temperature measurement can also be carried out in areas that are not safe or where contact temperature measurement is difficult, ie to achieve the purpose of testing and to protect personal safety. It is hoped that in the near future, the standard can include such a temperature measurement method as a standard, allowing it to be used in certain specific equipment and specific occasions.