An electromagnetic flow meter, also known as a magmeter, is a type of flow meter used to measure the flow rate of conductive fluids. It operates based on the principle of electromagnetic induction.
The basic construction of an electromagnetic flow meter consists of a flow tube or pipe section made of a non-magnetic material, such as stainless steel or plastic. Inside the flow tube, there are two electrodes mounted diametrically opposite to each other. These electrodes are in contact with the fluid being measured.
When the fluid flows through the flow tube, it acts as a conductor and creates a magnetic field perpendicular to both the fluid flow direction and the electrodes. The electrodes, connected to an external power source, generate a magnetic field within the flow tube perpendicular to the fluid flow and the existing magnetic field.
As per Faraday's law of electromagnetic induction, when a conductive fluid moves through the magnetic field, an electromotive force (EMF) is induced across the electrodes. The magnitude of this induced EMF is proportional to the fluid's velocity and its magnetic field strength.
By measuring the induced EMF, the flow meter can determine the fluid velocity, and subsequently, the volumetric flow rate. The flow meter may also incorporate a signal processor to convert the EMF into a digital or analog output that represents the flow rate.
Electromagnetic flow meters are commonly used in various industries to measure the flow of conductive fluids, such as water, wastewater, slurries, and chemicals. They offer advantages like high accuracy, wide rangeability, low pressure drop, and the ability to measure bi-directional flow. However, it's important to note that electromagnetic flow meters require a conductive fluid for accurate measurements and may not work with non-conductive liquids, such as oils or gases.