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Look at the electromagnetic flowmeter. Advantages and disadvantages should be memorized.

An electromagnetic flowmeter is an inductive meter that measures the volumetric flow of a conductive medium in a tube according to Faraday's law of electromagnetic induction. Structurally, the electromagnetic flowmeter is composed of a sensor that directly contacts the pipeline medium and an upper signal converter. It has been widely used in industrial technology and management departments such as chemical industry, environmental protection, metallurgy, medicine, papermaking, water supply and drainage.

The main advantages of electromagnetic flowmeter

(1) The output of the electromagnetic flowmeter is only proportional to the average flow velocity of the measured medium, and is independent of the flow state (laminar or turbulent flow) under a symmetric distribution. Therefore, the electromagnetic flowmeter has an extremely wide measuring range, and its range ratio can reach 20:1, and some even reach a range ratio of 100:1.

(2) The scope of industrial electromagnetic flowmeters is extremely wide, ranging from a few millimeters to several meters, and there are existing flow calibration devices with a diameter of 3m in China, which lays a foundation for the application and development of electromagnetic flowmeters.

(3) The sensor of the electromagnetic flowmeter has a simple structure, and there are no movable parts in the measuring tube, and there are no throttling parts that hinder the flow of the fluid. Therefore, when the fluid passes through the flowmeter, it does not cause any additional pressure loss, and is one of the flowmeters with the lowest energy consumption in the flowmeter.

(4) The electromagnetic flowmeter has no mechanical inertia and is sensitive to the reaction. It can measure the instantaneous pulsating flow rate and also measure the flow in both the positive and negative directions.

(5) It can measure the flow rate of dirty medium, corrosive medium and suspended liquid-solid two-phase flow. This is due to the fact that there is no obstructive flow component inside the metering tube. Only the measuring tube lining and the electrode are in contact with the fluid to be measured, and the material can be selected according to the nature of the fluid to be measured. For example, polytrifluoroethylene or polytetrafluoroethylene can be used as a lining to measure corrosive media such as various acids, alkalis, and salts. The use of wear-resistant rubber as the inner liner is particularly suitable for measuring wear with solid particles. Larger slurry, cement slurry and other liquid-solid two-phase flow and various suspended liquids such as fiber liquid and pulp.

(6) Electromagnetic flowmeter is a volume flow measuring instrument. During the measurement process, it is not affected by the temperature, viscosity and density of the measured medium in terms of conductivity (in a certain range). Therefore, the electromagnetic flowmeter can be used to measure the flow rate of other conductive liquids only after being calibrated by water.

Main disadvantages of electromagnetic flowmeter

(1) It cannot be used to measure gases, vapors, and liquids containing a large amount of gas.

(2) Cannot be used to measure liquid media with very low conductivity. For mediums such as petroleum products or organic solvents, the current electromagnetic flowmeter is still powerless.

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