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When it comes to flow meters, everyone thinks of electromagnetic flow meters. Indeed, they are a popular and widely used type of flow meter these days. But do people know how electromagnetic flow meters work and what their resistance to interference is like? Next, I will take you all into the “world” of electromagnetic flowmeters; let’s take a look together! An electromagnetic flowmeter is an instrument that utilizes the principle of electromagnetic induction to measure the flow rate of conductive fluids, based on the electromotive force generated when such fluids pass through an external magnetic field. Common knowledge on the use of electromagnetic flowmeters: They are used to measure the flow rate of conductive liquid media. The temperature of the medium should not exceed 120 degrees Celsius, the pressure should not exceed 1.6 MPa; they should not be used under negative pressure conditions. The flow velocity must be at least 0.3 m/s. The medium being measured should not contain many magnetic substances or bubbles. There should be minimal pressure loss in the fluid being measured, with a measurement accuracy of up to 0.5%. The range ratio is 1:20. Their measurement principle is based on Faraday’s law of electromagnetic induction. Classification of electromagnetic flowmeters: Based on the configuration of the output signal connection and the excitation (or power supply) connection, they are classified into four-wire and two-wire types. Classified by the assembly method of the converter and sensor, there are separate-type and integrated-type. Classified by the connection method between the flow sensor and the pipeline, there are flange type, clamping type, sanitary type, and insertion type. Classified by whether the sensor’s electrodes come into contact with the liquid being measured, there are contact type and non-contact type. Classified by the structure of the flow sensor, there are short-tube type and insertion type (insertion-type electromagnetic flowmeter). Classified by application, there are general-purpose types, explosion-proof types, sanitary types, water-intrusion-resistant types, and submersible types for measuring flow in open channels (open-channel flow meters). Features of electromagnetic flowmeters: 1. The measurement is not affected by changes in fluid density, viscosity, temperature, pressure, or conductivity ； 2. There are no components that impede flow inside the measuring tube, resulting in no pressure loss; relatively short straight sections are required. Has a unique adaptability for slurry measurement ； 3. Select the sensor lining and electrode materials appropriately, that is, those with good corrosion and wear resistance ； 4. The converter adopts a novel excitation method, featuring low power consumption, stable zero point, and high precision. The flow ratio can reach 150:1 ； 5. The converter can be integrated with the sensor or used as a separate unit ； 6. The converter is equipped with a 16-bit high-performance microprocessor and a 2x16 LCD display, enabling easy parameter setting and reliable programming ； 7. The flow meter is a two-way measurement system, equipped with three accumulators: total forward flow, total reverse flow, and total difference flow ； It can display forward and reverse flow rates, and offers various outputs: current, pulse, digital communication, HART ； 8. The converter uses surface mount technology (SMT) and features self-check and self-diagnosis functions ； 9. The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, or conductivity. The voltage signal generated by the sensor is linearly related to the average flow velocity, thus ensuring high measurement accuracy. 10. There are no flow-blocking elements inside the pipeline, so there is no additional pressure loss ； There are no moving parts inside the measurement pipeline, so the sensor has an extremely long lifespan. 11. Since the induced voltage signal is generated throughout the space filled with magnetic field and represents an average value over the cross-section of the pipe, the straight pipe section required for the sensor is short, with a length of 5 times the pipe diameter. 12. The converter utilizes the latest and most advanced microcontrollers (MCUs) and surface mount technology (SMT) available internationally, offering reliable performance, high precision, low power consumption, stable zero point, and easy parameter setting. Click on Chinese to display the LCD, which shows cumulative flow rate, instantaneous flow rate, flow velocity, flow percentage, and more. 13. A two-way measurement system that can measure forward flow and reverse flow. Special production processes and high-quality materials are used to ensure that the product’s performance remains stable over an extended period of time. An electromagnetic flowmeter consists of two main components: an electromagnetic flow sensor and an electromagnetic flow converter, and it operates on the principle of Faraday’s law of electromagnetic induction. The main components of a sensor are the measurement tube, electrodes, excitation coil, core and yoke, and housing. The measuring tube of the sensor is a short tube made of a non-magnetic alloy lined with insulating material, with a diameter of D. Two electrodes pass through the wall of the tube in the direction of the tube diameter and are fixed to the measuring tube, with their electrode tips being essentially level with the inner surface of the lining. When the excitation coil is excited by bidirectional square wave pulses, a working magnetic field with a flux density of B is generated in a direction perpendicular to the axis of the measurement tube. At this time, if a fluid with a certain conductivity flows through the measuring tube at an average flow velocity V, it will cut the magnetic field lines, thereby inducing an electromotive force E. The electromotive force E is proportional to the product of the magnetic flux density B, the inner diameter D of the measuring tube, and the average flow velocity V, that is, E∝BVD. The electromotive force E (flow signal) is detected by the electrodes and sent to the converter via a cable. The converter amplifies the flow signal, enabling it to display the flow rate and total volume, and can also output signals such as pulses and analog current. The converter of the LDG type electromagnetic flowmeter is an intelligent instrument with a Chinese LCD display. Due to the diverse classification and characteristics of electromagnetic flowmeters, as well as their wide range of applications, it is essential to choose the appropriate type of electromagnetic flowmeter when making a selection.