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Today, this article mainly focuses on knowledge related to electromagnetic flowmeters. First, let’s take a look at the lining of the sensor in electromagnetic flowmeters. One of the basic conditions for the operation of an electromagnetic flowmeter is that the normal current on the inner wall of the measurement tube, except at the electrodes, should be zero. This requires the wall of the measurement tube to be insulated, as this prevents the induced electromotive force from being short-circuited by the metal tube. Therefore, the inner wall of the conductive metal measurement tube and the flange surfaces are lined with insulating materials. Such insulating layers also confer properties such as corrosion resistance and wear resistance. Polytetrafluoroethylene is commonly used as the insulating material; other possible materials include rubber, polyvinyl chloride, polyurethane rubber, and industrial ceramics. The polytetrafluoroethylene used here has very stable chemical properties and is resistant to corrosion by boiling hydrochloric acid, sulfuric acid, aqua regia, and strong alkalis. Next, let’s talk about the measuring electrodes of electromagnetic flowmeters. The electrodes of electromagnetic flowmeters come into direct contact with the liquid being measured; therefore, they must be corrosion-resistant, wear-resistant, leak-proof in structure, and non-magnetic. The material for the three pairs of measurement electrodes is 316L, which is suitable for industrial wastewater as well as weakly corrosive acid, alkali, and salt solutions, and it is also inexpensive. The corrosion resistance of the electrode pair against the measuring medium is the primary factor to consider when selecting materials; metal materials other than 316L can be used, such as molybdenum-containing acid-resistant steel, Hastelloy B and C, titanium, tantalum, platinum-iridium alloys, etc. By using the same material for the ground electrode as that of the measuring electrode, it is possible to connect the conductive liquid to the signal of the converter in a reliable and stable manner as a reference point for the differential flow signal; this results in a polarization potential that is similar or roughly equal to that of the liquid, allowing the instrument to output a stable signal. Magnetic circuit system The function of the magnetic circuit system is to generate a uniform direct current or alternating current magnetic field. DC excitation includes a constant magnetic field generated by a permanent magnet, as well as a constant magnetic field produced by a DC current. The AC excitation used in this article employs a low-frequency sine wave of 5 Hz for excitation. In the measuring tube of a non-full-bore electromagnetic flowmeter sensor, there are two excitation windings located at the top and bottom. The excitation circuit of the converter for such flowmeters generates an excitation current that flows to the excitation coils, thereby creating a working magnetic field. Finally, let’s take a look at the measuring tube of the electromagnetic flowmeter. The measuring tube is located within a magnetic field, at the center of the sensor, through which the fluid flows. It must be able to withstand the working pressure of the fluid medium, as well as provide electrostatic shielding for the measuring electrodes from the excitation coils. Therefore, the material of the measuring tube must be non-magnetic, have high electrical resistance and low thermal conductivity, as well as possess certain mechanical strength. Common materials used include stainless steel, fiberglass, aluminum, and other high-strength materials. The material of the measuring tube here is stainless steel. 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/2012717174126829.jpg