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Ultrasonic level gauges are widely used in industrial settings, but their measurement accuracy is susceptible to the influence of installation conditions and operating environment factors. Below are the cause analyses and solutions for four common faults: 1. Measurement in the blind zone. Fault symptoms: Full scale indication, arbitrary fluctuating values, or no change in data. Cause analysis: Ultrasonic level gauges have inherent blind zones (typically, the blind zone for a 5-meter range is around 0.3–0.4 meters) ； The blind zone for a 10-meter range is approximately 0.4–0.5 meters). When the liquid level rises and enters the blind zone, the instrument is unable to distinguish the echoes effectively, resulting in signal loss and erratic output. Countermeasures: Preventive installation: When installing, it is necessary to leave a margin for the blind zone, ensuring that the distance between the highest liquid level and the lower edge of the probe is always greater than the blind zone requirement specified by the instrument. Preliminary communication: When selecting a product, it is necessary to provide the supplier with detailed operating conditions (such as range and maximum liquid level) so that the technical staff can determine whether the installation height is appropriate. II. Stirring inside the container causes fluctuations in the liquid level. Fault symptoms: signal loss, severe fluctuations in data, or unstable echoes. Cause analysis: Stirring can cause the liquid surface to become uneven, resulting in undulations or swirls. A fluctuating liquid surface causes diffuse reflection of ultrasonic waves, resulting in a significant reduction in the effective acoustic energy returning to the probe (it can usually drop to less than half the signal strength at a calm surface). Solution: Replace with a gauge of larger range. In fluctuating environments, it is recommended to select a gauge with a range that is 2–3 times greater than the actual required range (for example, a 5-meter range gauge should be replaced with one having a 10-meter or 15-meter range) in order to use higher transmission power to capture the weakened echoes. Installation of a guide tube: For non-viscous liquids, a guide tube (static water pipe) can be installed; the probe is placed on this guide tube to carry out measurements, and the relatively stable liquid level inside the tube enables the acquisition of reliable echoes. Change of signal system: If it was originally a two-wire system, it is recommended to switch to a four-wire ultrasonic level gauge with greater power. III. Foam on the liquid surface: Fault symptom: The instrument keeps searching and displays “signal loss” or interruption of the signal. Cause analysis: Foam has a strong absorption and scattering effect on ultrasonic waves. When the foam coverage area exceeds 40%-50% of the liquid surface, the majority of the emitted sound waves are absorbed, preventing the probe from receiving any meaningful echo signals. Solution: Install a waveguide: A waveguide can significantly reduce foam accumulation at the pipe opening, thereby improving the measurement conditions. Alternative technical solution: It is recommended to replace the ultrasonic level gauge with a radar level gauge. Radar waves (microwaves) have strong penetration capabilities; they can usually penetrate foam layers of up to 5 centimeters in thickness, making them more adaptable. IV. There are electromagnetic interference issues at the site: irregular fluctuations in data, drifting display values, or signal interruptions. Cause analysis: Equipment on site such as frequency converters, high-power motors, and welding machines generate strong electromagnetic interference. These interference signals may be picked up by the probe, or transmitted into the instrument’s circuitry via the power cable, thereby overwhelming the actual echo signals. Handling measures: Reliable grounding: The instrument must be grounded separately (it cannot share a ground terminal with other devices) to discharge any interfering currents on the circuit board. Independent power supply: The power source should be taken separately from the lighting or control circuit, to avoid sharing the same power system as frequency converters or high-power motors. Physical isolation and shielding: Install it as far away as possible from sources of interference such as frequency converters and high-power motors. If it is not possible to stay at a distance, a metal enclosure must be installed around the instrument for electromagnetic shielding, and the enclosure must be properly grounded. Summary recommendation: When dealing with faults in ultrasonic level gauges, it is recommended to follow the principle of \"checking the installation first, and then examining the environment.\" If there is foam, severe fluctuations, or strong interference at the site, and these issues cannot be resolved through conventional installation methods, then a guided wave radar (radar level gauge) should be considered as an alternative solution. Xi’an Dinghua Electronics Co., Ltd., established in 1992 and currently located in Xi’an, Shaanxi Province, is a high-tech enterprise that specializes in the research and development, production, sales, and engineering services of radar level measurement instruments. At present, the company offers a range of products including radar level gauges, external measurement level instruments, fork-type level switches, electro-hydraulic actuators, ultrasonic flow meters, and external temperature sensors. All of these products have withstood numerous complex operational conditions in real-world settings, and they are widely used in industries such as petroleum, chemicals, power generation, coal mining, metallurgy, as well as food and pharmaceuticals. Professional selection guidance, excellent product quality, reasonable prices, fast delivery times, and comprehensive pre-sales, in-sales, and after-sales services…