How to maintain and inspect electromagnetic flowmeters

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Application: An electromagnetic flowmeter consists of a sensor and a converter. It operates based on Faraday’s law of electromagnetic induction, and is used to measure the volumetric flow rate of conductive liquids with a conductivity greater than 5 uS/cm; it is an inductive instrument for measuring the volumetric flow rate of conductive media. In addition to measuring the volumetric flow rate of ordinary conductive liquids, it can also be used to measure the volumetric flow rate of highly corrosive liquids such as strong acids and strong bases, as well as uniform liquid-solid two-phase suspensions like sludge, pulp, and paper pulp. It is widely used in industries such as petroleum, chemicals, metallurgy, light textiles, papermaking, food processing, pharmaceuticals, and environmental protection, as well as in areas like municipal management, water conservancy construction, and river dredging, for flow measurement. I. Zero-point inspection and adjustment for the maintenance of electromagnetic flowmeters: Before putting an electromagnetic flowmeter into operation, it is necessary to adjust the zero point while the electromagnetic flow sensor is filled with liquid and at rest, after powering it on. After coming online, it is also necessary to shut off the flow periodically under the operating conditions to conduct zero-point checks ； Especially for precipitated or easily contaminated electrodes, as well as non-cleaning fluids containing solids, more inspections should be carried out during the initial operation phase in order to gain experience and determine an appropriate inspection schedule. Electromagnetic flowmeters with AC excitation are more prone to zero drift compared to those with rectangular wave excitation; therefore, extra attention should be paid to their inspection and adjustment. II. Regular inspection of the electrical properties of the sensor as part of electromagnetic flowmeter maintenance: Measure the resistance between the electrodes briefly: Disconnect the signal connection between the sensor and the converter, ensure that the sensor is filled with liquid, and use a multimeter to measure the resistance values between the two electrodes and the ground terminal. Check whether these values fall within the range specified by the manufacturer, and ensure that the two measured values are roughly equal ； Record the resistance value obtained during the first measurement; this value is useful for later determining the cause of sensor failures (such as whether the deposit layer is conductive or insulating).