The main criteria for selecting a thermometer
The use of the thermometer is mainly determined by the measurement range. Whether it is the measurement voltage or the initial value of the measurement area, it should be in line with the requirements of the measurement work. The larger the measurement voltage is, the smaller the resolution is, so the accuracy is higher. Especially when the initial value of the measurement temperature is low, the accuracy will be doubled if a large measurement voltage is selected, so it is recommended to select the smallest possible measurement voltage.
The initial value of the measurement area determines the sensitivity of the spectrum, as well as the type of the detector. The measurement error is due to the wrong adjustment of the emissivity. The short-wave sensor is obviously smaller than the long-wave sensor, so the hot film sensor ( 8～14μm) at 800℃, the measurement error caused by the wrong adjustment of the emissivity will be five times larger than that of the germanium-photodiode sensor (1,1～1,6μm). The permissible measuring range of the germanium photodiode sensor is from about 250° C.
For example, in the ceramic industry or in the combustion process of power plants, the measurement range is usually from 0 to 1300 °C. In order to avoid large errors, a thermometer with a short-wave detector should be selected. Although its highest temperature measurement ranges from 250 to 1300°C
Another criterion for selecting a suitable pyrometer is the spacing ratio. This refers to the proportional relationship between the measurement distance and the diameter of the measurement point. If the measured object is small and the measurement distance is large, or the so-called "hot spot" is on a large area, a large spacing ratio is required. On the contrary, if the measuring point has a large area, since the sensor has a stable output signal for the measuring point, it is recommended to use a small spacing ratio.
Another thing to be sure is whether the thermometer is equipped with a sight device, because the sight device will increase the cost by 50%. The key here is a price. When measuring objects in a large area, it is usually not necessary to assemble the sight. It is replaced by an external sight, which will be used for correction of the thermometer when it is installed, so that there is a price advantage, and only one sight is needed for many measurement locations.
For small measurement objects or distant measurement distances, it is necessary to be able to aim at any time. In a light-transmitting mirror with a scale on the dashboard, people can see the actual size of the measurement point. The cheapest one is to point the point with a laser, but it can only measure point by point. When measuring closed furnaces and similar types, it is necessary A ** window. Therefore, it is necessary to decide whether the thermometer is needed, and what functions do South Africa want? Such as leveling functions, special value storage, boundary contact or computer interface, for adapting the pyrometer to the measured surface, the possibility of emissivity adjustment is necessary, other functions can be adjusted inexpensively by connecting the recorder, device or program-controlled machine to achieve. In addition, for some applications, the appearance structure is also a decisive factor. At a higher ambient temperature, the thermometer only has an optical part with a lens, and is connected to the electrical part by a light-conducting cable. It is placed away from high-temperature areas. The advantage is that, Cooling devices can be saved.
