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As one type of industrial flow measurement instrument, electromagnetic flowmeters have certain techniques and considerations regarding their selection. I would like to discuss these with everyone, in the hope of contributing to the proper selection of electromagnetic flowmeters. 1. Application Overview Electromagnetic flowmeters are used in a wide range of applications. Based on the application scenario, they are classified into large-diameter, medium and small-diameter, small-diameter, and micro-diameter types. Large-diameter electromagnetic flowmeters are commonly used in water supply and drainage projects, while medium and small-diameter ones are often used for measuring fluids that are difficult to measure such as those with both solid and liquid components, or in applications with high requirements regarding flow measurement and control. Small-diameter and micro-diameter flowmeters are typically used in industries with strict hygiene requirements such as the pharmaceutical industry, food industry, and bioengineering. 2. Accuracy grade and functions The functions of electromagnetic flowmeters available on the market vary greatly; some simple models are designed only to measure one-way flow, outputting an analog signal that drives subsequent measuring instruments ； The multi-functional meter features the ability to measure two-way flow, range switching, upper and lower flow limit alarms, empty pipe and power loss alarms, small signal rejection, flow display and total volume calculation, automatic verification and fault self-diagnosis, communication with a host computer, and motion configuration. Some models of instruments offer a serial digital communication function with various communication interfaces and dedicated chips (ASICs) to connect to HART protocol systems, PROFIBUS, FF fieldbuses, and others. The performance of general-purpose electromagnetic flowmeters available on the market varies greatly; some have high precision and numerous functions, while others have lower precision and simpler functions. Instruments with high precision have a basic error of (±0.5%～±1%)R, while those with low precision have an error of (±1.5%～±2.5%)FS; the price difference between the two types is 1 to 2 times. Therefore, in applications where high measurement accuracy is not required (for example, in non-trade accounting where control is the only goal and only high reliability and good repeatability are needed), it is not economical to use high-precision instruments. 3. Flow rate, full-scale flow, range, and diameter: The diameter of the instrument selected does not necessarily have to be the same as that of the pipe; it should be determined based on the flow rate. The process industry transports liquids with different viscosities such as water, and the pipe flow velocity is generally the economic flow velocity of 1.5 to 3 m/s. Electromagnetic flowmeters are used in such pipes, and the sensor diameter needs to be the same as that of the pipe. For electromagnetic flowmeters, the liquid flow velocity at full scale can be selected within the range of 1–10 m/s, which is a fairly wide range. In principle, there is no limit on the maximum flow velocity; however, it is generally recommended not to exceed 5 m/s, unless the lining material can withstand the impact of the fluid flow. In some newly constructed systems where the flow rate is low at the beginning of operation or where the flow velocity is low, considering measurement accuracy, the diameter of the instrument should be smaller than that of the pipe, with an adapter pipe used for connection. In practical applications, it rarely exceeds 7 m/s, and values over 10 m/s are even rarer. The lower limit of the flow velocity at full scale is generally 1 m/s, while for some model instruments it is 0.5 m/s. For more information, please visit the company’s official website at http://www.yb1518.com/. Please keep this link when reproducing the content! http://www.yb1518.com/UploadFiles/2012717174126829.jpg