What is Magnetic flow meter:
The flow rate of fluids that conduct electricity, such as water or molten metal, can be measured using an electromagnetic flowmeter whose principle of
operation is based on the laws of electromagnetic induction. When a conductor of length L moves at
right angles to a magnetic field of density B at a velocity v, an induced e.m.f. e is generated, given by: e = BLv.
With the electromagnetic flowmeter arrangement is achieved, the fluid is the conductor and the e.m.f. is detected by two electrodes placed across the diameter of the non-magnetic tube.
Rearranging e = BLv by this we get,
velocity, v = e/BL
Thus with B and L known, when e is measured, the velocity of the fluid can be calculated.
Advantages of electromagnetic flowmeters
(i) Unlike other methods, there is nothing directly to impede the fluid flow.
(ii) There is a linear relationship between the fluid flow and the induced e.m.f.
(iii) Flow can be metered in either direction by using a centre-zero measuring instrument.
Applications of electromagnetic flowmeters are found in the measurement of speeds of slurries, pastes and viscous liquids, and they are also widely used in the water production, supply and treatment industry.
