A magnetic flow meter (mag meter, electromagnetic flowmeter) is a transducer that measures fluid flow by the voltage induced across the liquid by its flow through a magnetic field.
Magnetic Flow Meter
Image Courtesy: Yokogawa
A magnetic field is applied to the metering tube, which results in a potential difference proportional to the flow velocity perpendicular to the flux lines. The physical principle at work is electromagnetic induction.
The magnetic flow meter requires a conducting fluid, for example, water that contains ions, and an electrical insulating pipe surface, for example, a rubber-lined steel tube.
Principle of Operation
Simply, Magnetic Flow Meters work on Faraday’s Law of Electro-Magnetic Induction.
The Two Blue dots in the animation indicate electrodes. The Copper coils (red blocks – magnets) on top & bottom of the instrument are electro-magnets used to generate a magnetic field.
When there is no fluid flow then the induced voltage between electrodes is Zero.
When a fluid flows through the magnetic field, the two electrodes pick up the voltage and it is proportional to fluid flow rate.
That’s it. Very Simple.
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