Limitations of the use of electromagnetic flowmeters

Limitations of the use of electromagnetic flowmeters Because traditional orifice plates have serious measurement performance defects, in industrial water supply and drainage, urban tap water and heating systems, electromagnetic flowmeters are considered to be an ideal measurement method that can replace orifice plates. The volume is increasing day by day. Electromagnetic flowmeters do have many advantages, such as high measurement accuracy, no pressure loss, and measurement of dirty fluids, which make the use of electromagnetic flowmeters limited. Due to the serious measurement performance defects of traditional orifice plates, it is used in industrial water supply and drainage, In urban tap water and heating systems, electromagnetic flowmeters are considered to be an ideal measurement method that can replace orifice plates, and their use is increasing day by day. Electromagnetic flowmeters do have many advantages, such as high measurement accuracy, no pressure loss, measurement of dirty fluids, and small maintenance workload. However, the shortcomings of electromagnetic flowmeters have not attracted enough attention from people, and are often overshadowed by those advantages that are often mentioned. In fact, after a comprehensive understanding of the advantages and disadvantages of electromagnetic flowmeters and a comparison with related flowmeters, it is not difficult to find that in many cases, ultrasonic flowmeters and internal venturi flowmeters are used. In terms of measurement effect and performance-price ratio, it may be better than using electromagnetic flowmeter, especially when electromagnetic flowmeter has become impossible, inner venturi or ultrasonic flowmeter may be the best choice. Regarding the ultrasonic flowmeter, a large number of documents have reported on it in recent years, so I won't repeat it in this article. The inner venturi tube flowmeter is a new type of differential pressure flow measurement instrument, which overcomes the measurement performance defects of the traditional orifice plate, and can be used to measure various liquids, gases and steam. When used to measure liquids, its measurement accuracy is equivalent to that of electromagnetic flowmeters, but the stability of measurement accuracy and the ability to adapt to working conditions (temperature, pressure) are higher than electromagnetic flowmeters. The highest pressure that the electromagnetic flowmeter can withstand the measured medium is mainly restricted by the pipe wall thickness and the sealing reliability of the electrode part. Because the eddy current in the tube wall will affect the magnetic flux in the tube, the tube wall cannot be made too thick; if the liquid pressure is too large, the sealing of the electrode part will become very difficult. At present, the pressure resistance of most electromagnetic flowmeter manufacturers' products is not more than 4Mpa. The maximum temperature that the electromagnetic flowmeter can withstand the measured medium mainly depends on the material of the lining, such as -40℃～180℃ for polytetrafluoroethylene, and less than 65℃ for neoprene. Polytetrafluoroethylene has higher temperature resistance, but poor wear resistance. It is not suitable for high flow rates, especially liquids containing more solid particles.