What is a Magnetic Flow Meter?

Magnetic flow meters, also known as mag flow meters or mag meters, have many advantages, like no moving parts to wear, which makes them very reliable. They are by far one of the most popular flow measurement technologies in the world.

Magnetic flow meters use Faraday's law of electromagnetic induction to determine the velocity of a fluid flowing in a pipe. Magnetic flow meters consist of a non-magnetic flow tube, liner, electrodes and electromagnets to generate a magnetic field. In magnetic flow meters, a magnetic field is generated and directed to the fluid flowing through the tube.

Working principle Magnetic Flow Meter

Working principle Magnetic Flow Meter
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What do magnetic flow meters measure?

Magnetic flow meters only measure conductive liquids and do not work well with media below the required minimum conductivity. Conductive fluids are characterized by their ability to conduct electricity. This is because there are positively and negatively charged ion particles that can move freely. These ions enable conductivity, and the more ions there are, the higher the fluid's conductivity will be. Increasing the temperature of the liquid increases the activity of the ions and also increases the conductivity potential.

Known examples of conductive liquids are acids, alkalis, water-based slurries, salt solutions, hydrochloric acid, vinegar, lemon juice and sodium hydroxide.

Well-known examples of nonconducting fluids are deionized water, ultrapure water, distilled water, boiler feedwater, hydrocarbons, oils, greases and alcohols.

Advantages of using magnetic flow meters

The main advantages of using magnetic meters is that they have an obstacle-free design with no moving parts, which does not impede flow, requires less maintenance and can be used on very large pipelines. Accuracy over a wide flow range can reach ±0.5%.

Magmeters perform excellently in many municipal and processing applications and are the meter of choice for measuring conductive liquids such as water or slurry. Magmeters also have the advantage of being able to measure very low flow rates as well as very high volume flows.

Disadvantages of using magnetic flow meters

Magnetic flow meters are only effective on conductive fluids, and materials such as unmixed hydrocarbons and gases cannot be measured. However, magnetic materials themselves can also pose problems, as hydrodynamic effects can alter the normal flow pattern and disturb the velocity to the point of disrupting operation.

Depending on their size and capacity, magnetic flow meters can be relatively heavy, and those with higher resistance to corrosion and wear can be expensive.

Magnetic Flow Meter
Magnetic Flow Meter
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