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Faults during the calibration period of instruments generally occur during the installation and calibration phase; once resolved, they will not reappear under the same conditions in the future. Common faults during the commissioning period are usually caused by improper installation, environmental interference, and the effects of fluid properties. Faults caused by incorrect installation of electromagnetic flowmeters are common; for example, installing the sensor at the highest point of a pipeline where gases tend to accumulate ； Or installed on a vertical pipe from top to bottom, evacuation may occur ； Or there is no back pressure behind the sensor, and the fluid flows directly into the atmosphere, resulting in a non-full condition within the measurement tube. Sometimes, the presence of uniformly distributed tiny bubbles in the liquid being measured does not affect the normal operation of the electromagnetic flowmeter. However, as the bubbles grow larger, fluctuations occur in the instrument’s output signal. When the bubbles are large enough to cover the entire electrode surface, their passage over the electrodes can cause an instantaneous interruption in the electrode circuit, resulting in even greater fluctuations in the output signal. When an electromagnetic flowmeter driven by a low-frequency square wave is used to measure slurries with too high a solid content, slurry noise is also generated, causing fluctuations in the output signal. When measuring a mixed medium, if flow sensing is performed before the mixture has been homogenized, it will also cause fluctuations in the output signal. An inappropriate selection of electrode materials and the medium to be measured can also affect accurate measurements due to chemical reactions or polarization effects. The electrode material should be selected appropriately based on the instrument or relevant manuals.