How to choose the right infrared thermometer

Infrared Thermometer

The current infrared temperature measurement technology has been applied in many fields, such as quality control, monitoring and detection, fault diagnosis, safety and security, energy saving and environmental protection have played a more important role. In recent developments, non-contact infrared thermometer in the technology is becoming more mature, the performance is also constantly improved, functionality is also constantly enhanced. Compared with contact equipment, infrared thermometer response speed and non-contact to extend the life, the use of relatively safe.

There are three main categories of infrared thermometers on the market, portable, scanning, and in-line, with corresponding software derived from the application. And in accordance with different needs also formed a series of products, so in the application of the correct choice must be made to ensure the effect of temperature measurement.

Important indicators affecting the choice of infrared thermometer

1. Measurement range

 In the process of temperature measurement, the temperature extremes have a greater impact on the pyrometer, so the temperature range is the pyrometer must be concerned about the important indicators, and different models or series of products whose temperature range is different, each type of pyrometer in the factory on the calibration of the temperature range. So when choosing a pyrometer must refer to its adaptive range, not too narrow nor too wide. In the selection of the principle of blackbody radiation did not in the short wavelengths of the spectrum caused by the temperature of the radiation exceeded by the emission frequency error caused by the change in radiant energy, so the thermometer should be selected when the short-wave type of the main.

2. Consideration of the specification of measurement objectives

Infrared thermometer from the principle of temperature measurement to distinguish between single-color and two-color thermometer two, two-color thermometer two, two-color for the radiation colorimetric type. Single-color pyrometer in the determination of the target temperature, the area of the target to be measured should be filled with the full field of view of the pyrometer. So in the application should ensure that the target size is greater than half of the field of view, because if the target size is too small, the background of the radiant energy will be included in the range of temperature measurement, which will affect the micrometer readings, thus forming an error. On the contrary, the target size is large enough to make the target is larger than the field of view range, its radiant energy can all be captured by the micrometer, and to meet the measurement needs.

The principle of the two-color pyrometer makes it possible to complete the determination by two independent wavelength bands and to determine the detection value from their ratio. So when the measured target is very small, does not meet the full requirements, the measurement of the road with interference (smoke, dust), weakening the radiant energy will not have an impact on the measurement, according to the test of its energy attenuation to 95% of the time can also meet the measurement of the accuracy requirements. Therefore, the two-color pyrometer for small targets, sports targets can be measured, so for the movement of the target in the field of view can choose a two-color pyrometer.

3. Effect of optical resolution

The optical resolution is mainly determined by the ratio of D to S, i.e. the ratio formed by the distance from the pyrometer to the target and the diameter of the measured spot. If the pyrometer because of environmental interference and must be measured at a distance, and the measurement of the target is very small, you should choose a high optical resolution of the temperature measurement products. At this time, the higher the optical resolution, that is, the greater the ratio of D to S, the higher the cost of its pyrometer.

4. Influence of temperature measurement wavelength

The temperature of the material to be measured by the different reflectivity and surface characteristics will be different, the spectrum and wavelength will determine the measurement accuracy of the pyrometer, for the high reflectivity of the metal material, the reflectivity also exists in high and low. The wavelength for measuring metal materials in the high temperature region is usually infrared, with a wavelength of 0.18~1.0 μm. 1.6 μm, 2.2 μm, 3.9 μm and so on can be selected in different temperature regions. Meanwhile, the measurement and then encountered special materials in a certain wavelength is transparent, infrared light can be penetrated, these materials should choose a special determination of the wavelength, such as glass temperature measurement, it should be appropriate to change the wavelength, and its thickness must be guaranteed to measure. In the measurement of low-temperature region of the material, should choose 8 ~ 14μm wavelength. Such as the measurement of thin-film materials, should be based on the nature of its material wavelength selection, but also should take into account the thickness of the material, so as to determine the type of pyrometer and the range of measurement wavelength.

5. Influence of the temperature measurement environment

The operation of thermometers requires consideration of environmental factors, as environmental conditions have a large impact on them. It should be controlled when it can be adjusted, otherwise it will affect the accuracy of temperature measurement. When the ambient temperature is too high, or in dust, smoke, high temperature gas and other environments, all should choose the thermometer with protective equipment, such as protective sleeve, cooling equipment, or air blowing and other accessories. These accessories can help stabilize the environment during temperature measurement and solve its interference. When determining the choice of accessories, should try to require the realization of standardized services, as a way to reduce the cost of installation and application. If in the presence of smoke, dust or other particles in the environment, affecting the measurement signal should try to choose two-color pyrometer. In the noise, electromagnetic interference, vibration when the conditions can not be approached, or other harsh conditions should be selected light colorimetric pyrometer.

In addition, confined or hazardous materials can be encountered during measurements, and the pyrometer can only measure the material or environment through a window. The material must meet sufficient strength and be able to pass the operating wavelength of the pyrometer. It should also be determined whether the work requires a window for observation, so the appropriate window location and material should be selected to avoid interference in the measurement. In the application of low-temperature measurement, the choice of Ge or Si material as a window, which can not transmit light and the human eye can not be directly observed, the operator needs to be observed through the window on the measurement of the target, at this time should be used that can be transmitted through the infrared light can also be transmitted through the visible light of the material, in order to assist in the measurement.

Conclusions

Infrared thermometer in the application, it must be adapted to the working environment and the scope of determination, in order to correctly select the type of thermometer or auxiliary equipment, this is because the measurement environment, the object, the nature of the material, etc. will affect the infrared temperature measurement effect, the equipment itself to adapt to the range and the principle of measurement also affects the results of the measurements, so it is necessary to comprehensively examine the target before the measurement, and then select the appropriate thermometer.

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