What is the Principle of operation of Electromagnetic Flow Meters?


The working of these meters is based on Faraday’s Second Law of Electromagnetic Induction. It states that, a conductor moving in a magnetic field with the direction of its motion perpendicular to the magnetic field generates an EMF across it and the direction of the EMF is perpendicular to both, the magnetic field and the direction of motion. The generated EMF is proportional to the magnetic flux density, B, the velocity of conductor v and the length of the conductor l. In the flow meter the magnetic field is generated by exciting the coils and the conductor is the liquid itself, under measurement with the length equal to the diameter of pipe.

Thus EMF = B.v.d, where d is the diameter of the inner wall of flow meter.