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An electromagnetic flowmeter is a flowmeter that measures flow based on Faraday’s law of electromagnetic induction. The advantages of electromagnetic flowmeters are extremely low pressure loss and a wide measurable flow range. It has a wide range of applicable industrial pipe diameters, up to 3m at maximum. The output signal is linear with respect to the flow rate being measured, ensuring high accuracy. It can measure the flow rate of fluids such as acids, bases, salt solutions, water, sewage, corrosive liquids, as well as sludge, pulp, and paper pulp, with a conductivity of ≥5μs/cm. Electromagnetic flowmeters are divided into integrated and split types. Below is a detailed explanation of the reasons why split-type electromagnetic flowmeters are prone to damage. After initial calibration and normal operation for a period of time, various issues can arise during operation; common causes of these problems include deposits on the inner wall of the flow sensor, lightning strikes, and changes in operating conditions. 1. Changes in conditions and circumstances The main reasons are the same as those related to disturbances during the debugging phase; the only difference is that the source of disturbance does not appear during debugging but emerges during operation. For example, in the case of an electromagnetic flowmeter with suboptimal grounding protection, it operates normally during the calibration phase since there are no external disturbances from the factory. However, during operation new sources of disturbance arise – such as piping work near the measurement point or welding operations at a distance – which disrupt the normal operation of the instrument and cause significant fluctuations in the output signal. 2. Inner wall deposit layer Since electromagnetic flowmeters are used in situations where there are suspended solids or contaminants far more often than other flowmeters, the probability of the formation of an inner wall deposit layer and resulting interference is relatively high. If the conductivity of the coating layer is similar to that of the liquid, the instrument can still output signals properly, though the smoothness of the transition area creates a hidden obstacle that leads to measurement errors. In the case of a coating layer with high conductivity, the electromotive force between the electrodes will be short-circuited; whereas if it is an insulating coating layer, the surfaces of the electrodes become insulated, thereby breaking the measurement circuit. The latter two symptoms will prevent the instrument from functioning. 3. Lightning strike: Lightning strikes cause instantaneous high voltages and surge currents in the wiring, which can damage instruments when they come into contact with such currents. There are three pathways through which lightning can damage instruments: the power supply cable, the flow signal line between the sensor and the converter, and the excitation wire. However, from the analysis of component damage caused by lightning interference, it can be seen that the high voltages and surge currents that cause this interference mostly originate from the power supply lines in the control room, with the other two pathways being less common. It was also learned from the site where lightning-induced disturbances occurred that not only were the electromagnetic flowmeters affected, but other instruments in the control room also frequently experienced lightning-induced disturbances at the same time. Therefore, it is important to understand the significance of implementing lightning protection measures for the power cables of control room instruments when using units. Several existing project teams are already working on and exploring ways to address this issue. As a highly precise instrument, a flow meter requires strict adherence to its specifications not only during manufacturing and use, but also requires special attention during maintenance in order to prevent it from reaching the end of its useful life prematurely.