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Electromagnetic Flowmeter Measurement Principles and Applications - Focus on Microfluidic Control Technology

A measuring instrument for measuring the volume flow of a conductive medium fluid according to Faraday's law of electromagnetic induction. The electromagnetic flowmeter has a coating or lining inside the variator, and can measure the flow rate of various acid and alkali solutions for remote water, sewage, and industrial production, and is free from the temperature and pressure of the medium to be measured during the detection process. The effects of changes in flow conditions, etc., have a certain degree of stability and reliability, a wide measurement range, and a wide range of applications.

Electromagnetic flow meter measurement principle

The electromagnetic flowmeter is a measuring instrument for the volume of the conductive liquid and its measurement is based on Faraday's law of electromagnetic induction. We already know that when the conductor is in the magnetic field for anti-cut magnetic field lines, the conductor itself will generate a certain induced potential. Similarly, when the conductive fluid flows in the vertical direction in the magnetic field and cuts the magnetic induction force line, it also generates an induced potential on the electrodes on both sides of the pipe. According to the right-hand rule, the direction of the induced potential can be judged. According to the following formula, the magnitude of the induced potential can be calculated: Ex=BDv (1)

In the above formula, Ex represents conductor induced potential; B represents magnetic induction; D represents the internal diameter of the measuring pipe; and v represents the average flow rate of the liquid. Since the volume flow qv is equal to the product of the flow velocity v of the fluid and the cross-sectional area (πD)/4 of the pipe, substituting (1) into it, we know that:

Qv=(π D/4B)*Ex (2)

According to the formula (2), when the pipe diameter D and the magnetic induction intensity B are constant, the volumetric flow of the conductive liquid to be measured has a linear relationship with the magnetic induction potential. In this case, one electrode on both sides of the pipe can be introduced with the induced potential Ex. According to the formula (2), the magnitude of the induced potential can be measured, and the volumetric flow of the electro-liquid can be obtained. This is the measurement principle of the electromagnetic flowmeter.

Electromagnetic flowmeter application

Measuring tube

Electromagnetic flowmeters are instruments used to measure the volumetric flow of water used in everyday life and various industrial waters. In consideration of the corrosivity of the liquid being measured, the inside of the measuring tube is generally lined with lining material.

Excitation system

In order to overcome the shortcomings of pulsed DC excitation, high frequency excitation, low frequency excitation and other excitation methods, the measurement is not affected by the flow noise, and some manufacturers have developed dual excitation excitation methods. The electromagnetic flowmeter adopting this method has strong anti-noise capability, and has the advantages of high measurement accuracy and fast response speed.

Detection section

The detection part of the electromagnetic flow meter is mainly composed of electrodes and interference adjustment parts. The use of electromagnetic flowmeters for volume flow measurement of liquids is somewhat corrosive and the electrodes must be in direct contact with the fluid being measured. Therefore, the choice of electrode must have strong corrosion resistance.

Transmitting part

Because the electromagnetic flowmeter's main function is to convert the sensor's signal into a standard signal proportional to the volumetric flow of the measured liquid, the transmitter must have high stability, accurate accuracy, and strong Anti-jamming capability.

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