The VNLD series electromagnetic flowmeters are fully intelligent electromagnetic flowmeters developed by our company with advanced technologies from both home and abroad. They are suitable for measuring conductive liquids and volumetric flow rates in closed pipes, such as potable water, wastewater, various acid, alkali, and salt solutions, sludge, slurry, pulp, and liquid materials in the food industry.

Based on Faraday's Law of Electromagnetic Induction, the all-Chinese electromagnetic converter utilizes a high-speed central processing unit, offering rapid computation, high precision, and reliable measurement performance. The converter's circuit design incorporates advanced technology, with an input impedance of up to 10^15 ohms and common-mode rejection ratio exceeding 100dB. It effectively suppresses external interference and 60Hz/50Hz disturbances by over 90dB, enabling the measurement of fluids with lower conductivity. The sensor employs non-uniform magnetic field technology and a special magnetic circuit structure, ensuring stable and reliable magnetic fields while significantly reducing volume and weight, making the flow meter compact.

Operating Principle

The basic measurement principle of the VNLD series electromagnetic flowmeters is based on Faraday's law of electromagnetic induction, which states that when a conductor moves across the magnetic lines of force in a magnetic field, an induced electromotive force (EMF) is produced at its ends. The measuring tube of the flowmeter is made of a short non-magnetic alloy tube lined with insulating material. Two electrodes are inserted through the tube wall along the diameter and fixed on the measuring tube, with their electrode heads nearly flush with the inner surface of the lining. When the excitation coil is energized with a bidirectional square wave pulse, a working magnetic field with a flux density of B is generated perpendicular to the axis of the measuring tube. At this point, if a fluid with a certain electrical conductivity flows through the measuring tube, it will cut through the magnetic lines of force, and an EMF E will be induced. The EMF E is proportional to the flux density B and the product of the inner diameter d of the measuring tube and the average flow velocity v. The EMF E (flow signal) is detected by the electrodes and transmitted to the converter via a cable. The converter amplifies and processes the flow signal, displaying the fluid flow and outputting signals such as pulses and analog currents for flow control and regulation.