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Since the ultrasonic waves emitted by ultrasonic level gauges are invisible to the human eye, apart from faults in the level gauge itself, there are several other reasons that can cause abnormal operation at the site. The first reason is that stirring occurs inside the container at the site, resulting in significant fluctuations in the liquid level, which can affect the measurement performed by the ultrasonic level gauge. Fault symptoms: No signal or severe fluctuations in data. Reason: When ultrasonic level gauges mention measuring a certain distance in meters, it refers to a calm water surface. For example, an ultrasonic level gauge with a range of 5 meters means that it can measure distances up to 5 meters in still water; in reality, its effective range is 6 meters from the time it leaves the factory. When there is stirring inside the container, the water surface is not calm, and the reflected signal is reduced to less than half of the normal signal level. Solution: 1. Use an ultrasonic level gauge with a larger range; if the actual measurement range is 5 meters, then an ultrasonic level gauge with a range of 10 meters or 15 meters should be used for measurement. 2. If it is not possible to replace the ultrasonic level gauge, and the liquid in the tank is non-viscous, then a guide tube can still be installed; the probe of the ultrasonic level gauge can be placed inside this guide tube in order to measure the liquid level, as the liquid surface inside the guide tube remains relatively stable. 3. It is recommended to change the two-wire ultrasonic level gauge to a four-wire one. Second: there is foam on the surface of the liquid. Fault symptom: The ultrasonic level gauge is constantly searching, or it displays a “signal loss” status. Reason: Foam absorbs ultrasonic waves significantly, resulting in very weak echo signals. Therefore, when more than 40-50% of the liquid’s surface is covered by foam, the majority of the signals emitted by the ultrasonic level gauge are absorbed, resulting in the level gauge not receiving any reflected signals. This has little to do with the thickness of the foam; it is mainly related to the coverage area of the foam. Solution: 1. Install a wave guide, and place the probe of the ultrasonic level gauge inside this wave guide in order to measure the level; this way, there will be much less foam inside the wave guide. 2. Replace it with a radar level gauge for measurement; the radar level gauge can penetrate foam up to 5 centimeters thick. The third one ； The high temperature in the on-site tanks or containers affects the measurement of ultrasonic level gauges. Fault phenomenon: Measurement is possible when the water surface is close to the probe, but not possible when it is far away. When the water temperature is low, the ultrasonic level gauge functions normally; however, when the water temperature rises, the ultrasonic level gauge can no longer detect the level. Reason: Liquid media generally do not produce steam or mist at temperatures below 30–40°C; however, above this temperature, steam or mist is likely to form. The ultrasonic waves emitted by the ultrasonic level gauge weaken once as they pass through steam during transmission, and they weaken again when reflected back from the liquid surface. As a result, the ultrasonic signal that returns to the probe is very weak, making it impossible to carry out measurement. Moreover, in such an environment, the probe of the ultrasonic level gauge tends to accumulate water droplets, and these droplets prevent the transmission and reception of ultrasonic waves. Solution: 1. The measurement range needs to be increased; since the height of the tank is actually 3 meters, an ultrasonic level gauge with a range of 6 to 9 meters should be selected. It can reduce or minimize the impact of steam or fog on measurements. 2. The probe should be made of polytetrafluoroethylene or PVDF, and designed to have a physical seal; this prevents water droplets from forming on its emitting surface. As for emission surfaces made of other materials, water droplets tend to condense more easily on them. Fourth: There is electromagnetic interference at the site. Fault symptom: The data from the ultrasonic level gauge fluctuates irregularly, or it simply shows no signal. Reason: Industrial sites are equipped with many motors, frequency converters, and welding equipment, all of which can affect the measurement performed by ultrasonic level gauges. Electromagnetic interference will then exceed the echo signal received by the probe. Solution: 1. The ultrasonic level gauge must be properly grounded; by doing so, any interference on the circuit board can be discharged through the ground wire. Moreover, this ground connection must be separate; it cannot share the same ground as other devices. 2. The power supply cannot be the same as that of the frequency converter or motor, nor can it be drawn directly from the power supply of the drive system. 3. The installation location should be far away from frequency converters, frequency-driven motors, and high-power electrical equipment. If it is not possible to keep a distance, a metal instrument box must be installed outside the level gauge to provide isolation and shielding; this instrument box also needs to be grounded. Fifth: Entering the blind zone Fault symptom: Full scale or arbitrary data may appear. Reason: Ultrasonic level gauges all have blind zones; for a range of up to 5 meters, the blind zone is 0.3–0.4 meters. The range within 10 meters is 0.4–0.5 meters. Once it enters the blind zone, the ultrasonic wave will show arbitrary values and cannot function properly. Solution: 1. When installing, the height of the blind zone must be taken into consideration; after installation, the distance between the probe and the water level must be greater than that of the blind zone. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content! http://www.yb1518.com/UploadFiles/2011118121525564.jpg