Can the electromagnetic flowmeter adjust the flow rate?

　　Electromagnetic flowmeter with its, low loss and other advantages, in industrial production applications. But many users have questions about the function of electromagnetic flowmeter: electromagnetic flowmeter can adjust the flow? This article will provide you with a detailed analysis.

　　First, the working principle of electromagnetic flowmeter

　　To answer this question, first need to understand the working principle of electromagnetic flow meter. Electromagnetic flowmeter based on Faraday's law of electromagnetic induction, that is, conductive fluid in the magnetic field in motion, will produce induced electromotive force. Specifically, when a conductive fluid flows through the measuring tube inside the sensor, an electromotive force is induced on the two electrodes perpendicular to the magnetic field and the direction of the fluid because of the constant magnetic field generated by the excitation coil outside the measuring tube. This electromotive force is proportional to the average flow rate of the fluid, which is directly related to the flow rate. Therefore, by measuring the electric potential, you can calculate the fluid flow.

　　Second, electromagnetic flow meter can not directly adjust the flow

　　From the above principle can be seen, electromagnetic flow meter itself is just a flow measurement instrument, its function is limited to measuring the flow of fluids in the pipeline, and can not directly regulate the flow. Its output is proportional to the flow of electrical signals, the signal needs to be transmitted to the secondary instrumentation or control system, in order to display, record or control.

　　In other words, the electromagnetic flowmeter as “eyes”, can only “see” the size of the flow, and to truly realize the flow regulation, but also need other actuators, such as regulating valves, pumps and so on.

　　Third, how to use electromagnetic flowmeter to achieve flow control

　　Although the electromagnetic flowmeter can not directly adjust the flow, but can be used as the core element of flow measurement, and other equipment to form a closed-loop control system to achieve indirect control of the flow. Specific steps are as follows:

　　The electromagnetic flowmeter is installed in the pipeline that requires flow control, and its output flow signal is transmitted to PLC, DCS and other control systems. Control system according to the pre-set flow target value, and electromagnetic flowmeter measured actual flow value comparison, and according to the size of the deviation calculated the amount of regulation. The control system will send the adjustment signal to the actuator, such as control valves or frequency converter, so as to change the valve opening or pump speed, and finally realize the precise control of the flow.

　　Fourth, electromagnetic flowmeter selection factors to be considered

　　In practice, the choice of suitable electromagnetic flowmeter to ensure the accuracy and stability of flow control is critical. Selection, need to consider the following factors:

　　Fluid properties: including fluid conductivity, viscosity, temperature, pressure and so on. For example, the electromagnetic flow meter is only suitable for measuring the flow of conductive fluids, for oil, gas and other non-conductive fluids can not be used. Piping parameters: including pipe diameter, material, lining material, etc.. Select the electromagnetic flowmeter that matches the pipeline parameters, you can effectively avoid signal interference and measurement errors. Precision requirements: different application scenarios have different requirements for the accuracy of flow measurement. Need to choose the appropriate precision level of electromagnetic flowmeter according to the actual needs. Output signal: electromagnetic flowmeter output signal types include current signal, frequency signal, digital signal and so on. Need to choose the appropriate output signal type according to the interface requirements of the control system. V. Conclusion

　　In summary, the electromagnetic flowmeter itself can not directly regulate the flow, but can be used as a key link in the flow measurement, and other control equipment to form a closed-loop control system, to achieve the control of the flow. In practical application, you need to select the appropriate electromagnetic flowmeter according to the specific conditions, and correctly configure the control system, in order to give full play to its role, to achieve the desired control effect.