The electromagnetic flowmeter uses the principle of Faraday’s law of electromagnetic induction, that is, when a conductive object cuts a magnetic wire in a magnetic field, an induced electromotive force is generated in the conductor. Its induced electromotive force E is:
E = KBdV
The flow rate Q is: Q=3600VS
Where: K-meter factor
B-magnetic induction (T)
D-electrode spacing (m)
V-fluid average flow rate (m/s)
S-catheter cross-sectional area m2
When the flow rate is measured, the conductive liquid flows at a flow velocity V through a magnetic field perpendicular to the flow direction, and the flow of the conductive liquid induces a voltage proportional to the average flow velocity, and the induced voltage signal is detected by the electrode in direct contact with the liquid.
For the same flow meter S, B, and d are constant, so the flow rate is proportional to the magnitude of the induced electromotive force E (or flow velocity V).