Magnetic Flow Meters: How They Work & What Is It

An electromagnetic flow meter is a volumetric flow meter that does not have any moving parts. It is ideal for wastewater applications or any dirty liquid which is conductive or water based. Magnetic flow meters are also ideal for applications where low-pressure drop and low maintenance are required.

Magnetic flow meters will generally not work with hydrocarbons, distilled water, and many non-aqueous solutions.

How does a magnetic flow meter work?

Magnetic flow meters use a magnetic field to generate and channel liquid flow through a pipe. A voltage signal is created when a conductive liquid flows through the flowmeter’s magnetic field. The faster the flow of the fluid, the greater the voltage signal generated. Electrode sensors located on the flow tube walls pick up the voltage signal and send it to the electronic transmitter, which processes the signal to determine liquid flow.

What is the operating principle of a magnetic flow meter?

The operation of a magnetic flow meter or mag meter is based upon Faraday's Law, which states that the voltage induced across any conductor as it moves at right angles through a magnetic field is proportional to the velocity of that conductor.

As applied to the design of magnetic flow meters, Faraday’s Law indicates that signal voltage (E) is dependent on the average liquid velocity (V) the magnetic field strength (B) and the length of the conductor (D) (which in this instance is the distance between the electrodes).

Vortex Flow Meter

A vortex flow meter is a flow measurement device best suited for flow measurements where the introduction of moving parts presents problems. They are available in industrial grade, brass or all plastic construction. Sensitivity to variations in the process conditions are low and with no moving parts have relatively low wear compared to other types of flow meters.