The measurement principle of electromagnetic flowmeter is based on Faraday's law of electromagnetic induction. The sensor part is composed of coils, electrodes and insulating linings. During measurement, the excitation coil in the sensor is energized to generate a magnetic field. When the conductive fluid passes through the magnetic field, a small induced electromotive force is generated due to the force of cutting the magnetic lines of force. These tiny induced electromotive forces are generated by the electrodes. The induced electromotive force is collected and sent to the converter part of the instrument, where the signal is amplified, corrected, etc., and then converted into corresponding flow data through formulas, and finally displayed on the instrument or output to the host computer system.

Principle diagram

When a conductive fluid flows through a magnetic field perpendicular to the flow direction, the conductive liquid induces an induced voltage E that is proportional to the average flow rate. The induced voltage passes through two direct The electrodes in contact with the fluid are detected, amplified, filtered, and shaped by the converter, and sent to the MCU to complete the display and output control of instantaneous flow and accumulated flow. E=KBVD In the formula: E---Induced voltage? K---Instrument constant B---Magnetic induction intensity V---Measurement of average flow velocity in the pipe surface D---Diameter of the flow meter

Product Structure Diagram

A good electromagnetic flowmeter has high measurement accuracy and stable product performance. At present, the accuracy of electromagnetic flowmeters is generally 0.3 or 0.5, and some small diameter The product can achieve level 0.2. Due to the particularity of its measurement principle, the measurement medium needs to have a certain conductivity (generally greater than 5us/cm), and there are also certain requirements for measuring the starting flow rate (generally greater than 0.5m/s).

TSD electromagnetic flowmeter has many advantages when performing fluid flow, and is currently widely used in various industries.

(1) There are no flow-impeding parts in the measuring tube, no pressure loss, and relatively low requirements for straight pipe sections;

(2) High measurement accuracy, strong stability, and anti-vibration interference ability Strong;

(3) Measurement is not affected by changes in fluid density, viscosity, temperature, pressure and conductivity;

(4) Has a variety of electrodes and lining options, resistant to media Strong corrosion ability.

Of course, the electromagnetic flowmeter also has its unique limitations:

(1) The measurement medium must have a certain conductivity (generally greater than 5us/cm), and the measurement starts at the same time The flow velocity also has certain requirements (generally greater than 0.5m/s)

(2) The temperature of the measurement medium is limited by the lining material, and the measurement effect for high-temperature media is not good.

(3) It cannot measure gas, steam and other media.

(4) When the measuring electrode works for a long time, scaling may occur and needs to be cleaned before measurement.

(5) For highly viscous media and solid-liquid two-phase media Therefore, it is necessary to use high-frequency excitation method, and the low-frequency and low-magnetism accuracy is poor.

(6) Due to the limitations of the sensor structure principle, the cost of large-diameter products is too high, resulting in an increase in product diameter and a linear increase in price.

(7) Due to its principle limitations, the instrument sensor coil needs to be energized to generate a magnetic field. The estimated power consumption is relatively high and is not suitable for battery power supply.

Despite the above-mentioned shortcomings, electromagnetic flowmeters are still widely used in the measurement of most liquid media. Their excellent measurement accuracy and low maintenance costs are deeply loved by customers.

In summary, electromagnetic flowmeters have their own advantages and disadvantages. Users should choose appropriate flowmeter products based on industry and working conditions.