Electromagnetic flowmeter working principle and characteristics

1. Working principle of electromagnetic flowmeter

The working principle of electromagnetic flowmeter is based on Faraday's law of electromagnetic induction. In the electromagnetic flowmeter, the conductive medium in the measuring tube is equivalent to the conductive metal rod in the Faraday test, and the two electromagnetic coils at the upper and lower ends generate a constant magnetic field. When a conductive medium flows through it, an induced voltage is generated. Two electrodes inside the pipe measure the induced voltage produced. The measuring pipe is electromagnetically isolated from the fluid and measuring electrodes by a non-conductive lining (rubber, Teflon, etc.).

2. Characteristics of electromagnetic flowmeter

(1) The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure and conductivity. The sensor induced voltage signal is consistent with the average flow rate. Linear relationship, so measurement accuracy is high.

(2) There are no flow obstructions in the measuring pipe, so there is no additional pressure loss; there are no moving parts in the measuring pipe, so the sensor has an extremely long life.

(3) Since the induced voltage signal is formed in the entire space filled with magnetic fields and is the average value on the pipe surface, the sensor requires a shorter straight pipe section and a pipe length of 5 times. Diameter

(4) Only the lining and electrodes of the sensor part are in contact with the liquid being measured. As long as the electrode and lining materials are properly selected, they can resist corrosion and wear.