Nine issues you need to pay attention to when using infrared thermometers
Human infrared thermometers are mainly used to measure the temperature of the human body, while industrial infrared thermometers are, as the name suggests, mainly used in the industrial sector. However, it must be clarified that there is no specific medical or industrial infrared thermometer, because the manufacturing principle of infrared thermometers are the same. There are only high-precision, high-distance coefficient ratio, high-performance infrared thermometer and low-precision, low distance coefficient ratio and low performance of the infrared thermometer. As long as the emissivity of the infrared thermometer is set at 0.95 (human skin emissivity is generally this value, even if there is a difference, the impact is only within 0.2 degrees), is in line with the requirements of human body temperature measurement.
First, the human body infrared thermometer temperature measurement interval is small, 30 - 42.5 degrees, but the display is highly accurate. Industrial infrared thermometer range, such as measuring -50 - 2200 degrees.
Secondly, the human infrared thermometer needs to be close to the human body, 1-15cm or less, industrial infrared thermometer to be greater than 1M, such as measuring the temperature of steel, people can not be too close, some need to be about 10M. Measurement of near and far, the main thermometer issued by the strength of the infrared wave. Human infrared thermometer infrared wave is too strong will be harmful to the human body, but also do not need.
Therefore, we can choose the right thermometer according to the need can be divided into three aspects: performance indicators, such as temperature range, spot size, operating wavelength, measurement accuracy, response time, etc.; environmental and operating conditions, such as ambient temperature, window, display and output, protection accessories, etc.; other choices, such as ease of use, maintenance and calibration of the performance and price, etc., but also on the selection of infrared thermometers Have a certain impact.
3, infrared thermometer should be used hinged copper wire (cross-sectional area of about 50mm2) to form an electrical bypass, in order to protect them from welding current or lightning caused by the hazards. Pyrometer use, must avoid strong thermal radiation, especially unilateral strong thermal radiation.
4, electrical connection preparation (such as pyrometer signal cable, not and strong power line or control line parallel arrangement (for example, do not put the pyrometer signal line and strong power line and control line placed in the same pipe). If they must be placed in parallel, then, the distance between them should be maintained at more than 50CM, and the signal line with a metal pipe sleeve.
5, as far as possible, the use of automatic positioning (reset) role of the structure of the accessories, such as ball bearings, joint bearings, positioning fasteners.
They can prevent some lateral force acting on the pyrometer. To be clear: some lateral forces are not caused by mechanical installation, such as lateral forces caused by thermal expansion, lateral forces caused by wind, and lateral forces caused by vibration of agitators on some container scales, i.e., they are not caused by mechanical installation. Some scales must be connected to some accessories on the scale body (such as container scales feeding pipes, etc.), we should let them in the direction of the thermometer loading spindle as soft as possible, in order to prevent them from "eating" the thermometer's real load together and cause errors.
6, to take lightly put especially by the alloy aluminium elastomer made of small capacity pyrometer, any impact, fall, on its measurement performance may cause great damage. For large-capacity infrared thermometer, in general, it has a large self-weight, so the requirements in the handling, installation, as far as possible, the use of appropriate lifting equipment (such as hand-operated hoists, electric hoists, etc.). Installation of the thermometer base mounting surface should be flat, clean, without any oil film, adhesive film and so on. The mounting base itself should have sufficient strength and rigidity, generally require higher than the strength and stiffness of the pyrometer itself.
7. Although the infrared thermometer has a certain overload capability, overloading of the thermometer should still be prevented during the installation of the weighing system. It should be noted that even short-term overloading may cause damage to the thermometer.
During the installation process, if necessary, you can first replace the thermometer with a spacer of the same height as the thermometer, and then replace the thermometer. During normal operation, the thermometer should generally be equipped with mechanical structural parts for overload protection. If a screw is used to fix the thermometer, a certain tightening torque is required, and the screw should have a certain thread depth. Generally speaking, the fixed screw uses a high-strength screw.
8. No matter what the circumstances, the power lines and control lines should be twisted together at a degree of 50 turns/meter. If the thermometer signal line needs to be extended, a special sealed cable junction box should be used. If this type of junction box is not used and cables are directly connected (soldered terminals), special attention should be paid to sealing and moisture-proofing. After the connection is completed, the insulation resistance should be checked and must meet the standard (2000~5000M). If necessary, The thermometer should be recalibrated. If the signal cable is very long and high measurement accuracy must be ensured, a cable compensation circuit with a relay amplifier should be considered.
9. Horizontal adjustment
Level adjustment has two aspects. One is that the installation surface of the installation base of a single thermometer should be adjusted with a level. On the other hand, the installation surface of the installation base of multiple thermometers should be adjusted to a horizontal plane (with a level) as much as possible, especially for temperature measurement. In weighing systems with more than three instruments, more attention should be paid to this point. The main purpose of doing so is to make the load borne by each thermometer basically the same. The loading direction of each electronic floor scale infrared thermometer is determined, and when we use it, the load must be loaded in this direction. Lateral forces, additional bending moments, and torque forces should be avoided as much as possible.
