How to Correctly Improve the Accuracy and Measurement Principle of Electromagnetic Flowmeter

The measurement principle of the electromagnetic flowmeter is based on Faraday's law of electromagnetic induction. When a conductive liquid moves in a magnetic field to cut magnetic lines of force, an induced potential is generated in the conductor. The induced potential E is: E=KBVD, where: K-----instrument constant B-----magnetic induction intensity V-----measures the average flow velocity in the pipe section D-----measures the inner diameter of the pipe section When measuring flow, the conductive liquid flows through a magnetic field perpendicular to the flow direction at a speed V. The flow of the conductive liquid induces a voltage that is proportional to the average flow velocity. The induced voltage signal is detected by two or more electrodes in direct contact with the liquid, and is sent to the converter through a cable for intelligent processing, and then displayed on the LCD or converted into a standard signal of 4~20mA and 01kHz output.

How Mingyu correctly improves the accuracy of electromagnetic flowmeters: Flow measurement accuracy refers to the accuracy obtained by the flow measurement system, which is different from the accuracy of the flowmeter itself. Only if the flowmeter itself has good performance and high accuracy, it does not necessarily achieve high measurement accuracy. To ensure the accuracy of the flow measurement system, in addition to reasonable selection, correct installation and commissioning, and timely maintenance and care, the application of intelligent technology to properly compensate and correct the errors that may be introduced by the measurement part is also an effective method. For example, compensation for the temperature expansion coefficient of the liquid, compensation for the temperature, pressure and compression coefficient of the gas, compensation for the Reynolds number effect and flow expansion coefficient of the differential pressure flowmeter, compensation for the nonlinearity of the flow coefficient of various flowmeters, compensation for the temperature effect of the volumetric flowmeter and vortex flowmeter, compensation for the velocity distribution of the ultrasonic flowmeter, etc. This compensation and correction is to use a systematic method to deal with the errors inherent in the detection part that cannot be overcome by itself, so as to eliminate or basically eliminate them. Practice has shown that this method is simple, effective and promising.

How to correctly improve the accuracy of electromagnetic flowmeter: In view of the current situation that the measurement accuracy of electromagnetic flowmeter in water injection is generally lower than the theoretical measurement accuracy of flowmeter, according to the principle of electromagnetic flowmeter and the actual application conditions, the factors affecting the measurement accuracy of electromagnetic flowmeter under the on-site working conditions are analyzed one by one, and the weight relationship of each factor is found. It is inferred that the valve opening is too small, the pipe system inhales bubbles, the liquid contains dissolved gas, the reciprocating pump oscillates and the sediment layer covers the electrode as the main reasons; according to the main reasons, countermeasures are formulated and implemented, repeated on-site experiments and effect inspections are carried out, and finally a set of methods to improve the measurement accuracy of electromagnetic flowmeter under on-site working conditions is explored.

How to correctly improve the accuracy of electromagnetic flowmeters: Among the many methods to ensure measurement accuracy, online real-flow calibration occupies an important position. In the past, most of the flowmeters were calibrated using offline methods. Although the flowmeters calibrated using this method have higher accuracy after error correction, the reference conditions of the pipelines during calibration are different from those during actual use, the fluid properties during calibration are different from the fluids actually used, and the environmental conditions during calibration are different from the actual environment of the instrument use site, which causes additional usage errors and reduces the measurement accuracy. The online real-flow calibration method is an effective way to solve this problem. For example, the standard volume pipe connection port is reserved for the oil metering station during the construction phase. After the standard volume pipe is connected, the online real-flow calibration of each flowmeter in the metering station can be achieved through valve switching. Now, the online real-flow calibration method is also required at natural gas distribution stations.