Assessing the pros and cons of non-contact temperature measuring instruments
Non-contact temperature measuring instruments are designed based on the principle of thermal radiation of objects. During measurement, the temperature sensing element is not in direct contact with the object being measured, and is usually used to measure the temperature or surface temperature of high-temperature objects above 1000°C that move, rotate or react quickly.
The advantages are:
(1) Wide temperature measurement range (theoretically there is no upper limit). Suitable for high temperature measurement;
(2) During the temperature measurement process, the temperature field of the measured object is not destroyed and the original temperature field distribution is not affected;
(3) Can measure the temperature of moving objects;
(4) Thermal inertia is small. The response time of the detector is short. The temperature measurement response speed is fast. It is about 2-3s, making it easy to achieve rapid and dynamic temperature measurement. Under some specific conditions, such as nuclear radiation fields, radiation thermometry can make accurate and reliable measurements.
The disadvantages of non-contact temperature measurement instruments are:
(1) It cannot directly measure the true temperature of the measured object. To obtain the true temperature, the emissivity needs to be corrected. The emissivity is a parameter with quite complex influencing factors. This increases the difficulty of processing the measurement results.
(2) Because it is non-contact. The measurement of radiation thermometer is greatly affected by the intermediate medium. The treatment is under industrial site conditions. The surrounding environment is relatively harsh, and the intermediate medium has a greater impact on the measurement results. In this regard, the choice of thermometer wavelength range is very important.
(3) Due to the complex principle of radiation temperature measurement, the thermometer has a complex structure and a high price.
Non-contact temperature measurement instruments mainly include radiation thermometers, fiber optic radiation thermometers, etc. The former is divided into total radiation thermometers, brightness thermometers (optical pyrometer, photoelectric pyrometer) and colorimetric thermometers.
