Electro-magnetic flow meter | Electro-magnetic flow sensor

This page covers electro-magnetic flow meter basics and advantages based on magnetic flow sensor. It mentions working operation of electro-magnetic flow meter.

The flow meters are used in wide variety of applications. They are used as process control system in waste water treatment plants. They are also used in various industrial control processes such as food & beverage, chemical/pharma, pulse & paper etc.

Working operation of electro-magnetic flow meter

electro-magnetic flow meter

The figure-1 depicts simple magnetic flow meter with its principle of operation. It is based on faraday's law of electro-magnetic induction.

The faraday's law states that when conductive fluid flows through magnetic field of sensor, EMF (Electromotive force) is generated. The EMF between pair of electrodes is proportional to volume flow of liquid. Moreover EMF is perpendicular to the flow direction as well as to the direction of magnetic field. The amplitude of EMF can be expressed as follows.

E = K*B*D*v
E = Induced electric potential
K = Constant
B = Magnetic Flux density
D = Inner diameter of measuring tube
v = average velocity of fluid in axial direction of cross section of the electrodes

Advantages of electro-magnetic flow meter

Following are the advantages of electro-magnetic flow meter:
• Electromagnetic sensors are placed in line in the diameter of pipe. Hence they will not obstruct the flow of medium.
• As sensors are not immersed in the liquid, there are no moving parts and hence no tear or wear concerns.
• As electro-magnetic flow measurement method depends only on flow of volume; it does not have any effect in the measurement due to changes in temperature, density, pressure and viscosity.
• Due to above reason, electro-magnetic flow meter can be used for any type of conductive fluid measurement once it is calibrated with the water. Moreover it does not require any additional amount of correction.


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