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I. Overview The insert-type electromagnetic flowmeter is a device for measuring conductive liquids, based on Faraday’s law of electromagnetic induction. Due to its simple structure, light weight, easy installation, and low maintenance requirements, this type of instrument is used in petrochemical plants to measure the volumetric flow rate of non-corrosive (water supply and drainage) conductive liquids in closed pipelines. II. Working Principle, Characteristics, and Applications of Insertion-Type Electromagnetic Flow Meters (1) Measurement Principle The insertion-type electromagnetic flow meter is a device designed to measure conductive liquids, based on Faraday’s law of electromagnetic induction. The flow meter measuring tube has a housing made of insulating material; inside this housing are coils, an iron core, and a yoke, and two electrodes are located on the end faces of the housing. When the excitation coil is driven by bidirectional square wave pulses, a working magnetic field with a magnetic flux density of B is generated. When a fluid with a certain conductivity flows through the measuring tube at an average flow velocity V, it cuts the magnetic field lines, inducing an electromotive force E. The electromotive force E is proportional to the product of the magnetic flux density B and the average flow velocity V: E=KVB, where K is a structural coefficient. The electromotive force E (flow signal) is detected by the electrodes and sent to the converter via a cable. (II) Structural Features The insert-type electromagnetic flowmeter consists of two main parts: the sensor and the converter ； Converters and sensors can be configured as separate or integrated units. (III) The application range of the insert-type electromagnetic flowmeter is the same as that of a conventional electromagnetic flowmeter. (IV) Main technical features and applications of insert-type electromagnetic flowmeters 1. High accuracy. The measurement results are independent of changes in physical parameters such as flow velocity distribution, fluid pressure, viscosity, temperature, density, and conductivity. 2. Suitable for use on metal pipes with nominal diameters DN100-DN1800. 3. Wide range ratio. The range ratio can be as wide as 100:1. 4. It is resistant to corrosion and wear. In the sensor section, only the lining and electrodes come into contact with the liquid being measured; it is sufficient to select the electrode and lining materials appropriately. 5. The converter is equipped with a 16-bit high-performance microprocessor, features a 3-row 128*64 LCD matrix for displaying Chinese characters, offers convenient parameter setting, and ensures reliable programming. 6. The requirement for straight pipes is low: 5D in front and 3D at the back (D is the nominal diameter of the pipe). III. Installation of Insertion-Type Electromagnetic Flow Meters (1) Installation of the Separate Converter The separate converter should be installed as close as possible to the sensor; it can be mounted on a wall or a pillar. For outdoor installation, it should be placed inside an instrument box to avoid prolonged exposure to direct sunlight and rain. (II) Installation of the sensor (or integrated unit). For sensors (or integrated units) installed on pipes, an opening must be made in the pipe and a connection base (or pipe fitting) welded to it, after which the sensor (or integrated unit) is fixed to the connection base (or pipe fitting). 1. Technical requirements for installation on pipelines: (1) Choose a location with minimal vibration and avoid direct sunlight. (2) To ensure that the sensor always measures a fluid-filled conduit, the sensor can be installed at the lowest point of the U-shaped pipe. (3) If installed vertically or at an angle, the fluid should flow from bottom to top. (4) The fluid under test must fill the pipeline. (5) The sensor can be installed horizontally or vertically, as long as the geometric line connecting the two electrodes is perpendicular to the pipeline axis. (6) To further reduce the impact of entrained bubbles on measurements, the instrument can be installed away from the highest point of the pipeline. (7) A location that facilitates instrument wiring and reading should be selected. 2. The separate-type sensor (or integrated type) is installed on the user’s pipeline using a flanged ball valve. (1) Drain the liquid from the pipeline at the selected location. (2) Use oxy-acetylene cutting to create a circular hole with a diameter of Ф40-Ф50 at the selected location in the pipe, ensuring that the perimeter of the hole is as smooth as possible. (3) Remove the connection seat from the lower end of the ball valve and place it at the opening. (4) Install the sensor (or integrated unit) on the connection seat, add washers between the flange of the connection seat and the flange of the ball valve, and ensure that the flow direction indicator arrow points in the direction considered correct by the user. IV. Problems encountered in the use of plug-in electromagnetic flowmeters (1) Due to an inappropriate installation location of the flow sensor, the liquid inside the measurement tube is not completely filled, resulting in an “excitation” alarm. (II) The straight pipe section before the flow meter should be ≥ 5D, and the straight pipe section after the flow meter should be ≥ 3D (D is the nominal diameter of the pipeline). (III) When the liquid contains powder or particles, it causes the deposition of contaminants, leading to wear of the lining. (IV) Oscillations may occur if the liquid conductivity approaches the lower limit value. (5) The resistance of the sensor excitation coil (between EXT+ and EXT-) should be less than 60Ω. V. Conclusion The insert-type electromagnetic flowmeter boasts numerous advantages, including simple installation, wide applicability, excellent measurement performance, and ease of retrofitting existing devices. It is widely used for measuring the flow rates of various water-based fluids (fresh water, circulating water, wastewater, etc.), where the flow rates can vary significantly, and it plays an effective role in ensuring fluid balance and accurate measurement in such systems. Therefore, understanding its working principle, structure, characteristics, and solutions will help us use and maintain it more effectively. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content! http://www.yb1518.com/UploadFiles/201412269333291.jpg