Instrument Mesurement Knowledge

What is an Electromagnetic Flowmeter?

Views: 24     Author: Site Editor     Publish Time: 2022-05-09      Origin: Site

What is an Electromagnetic Flowmeter?

A magnetic flow meter (mag meter, electromagnetic flow meter) is a transducer that measures fluid flow by the voltage induced across the liquid by its flow through a magnetic field. 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.


If the magnetic field direction were constant, electrochemical and other effects at the electrodes would make the potential difference difficult to distinguish from the fluid flow induced potential difference. To show this in modern magnetic flowmeters, the magnetic field is constantly reversed, cancelling out the electrochemical potential difference, which does not change direction with the magnetic field. This however prevents the use of permanent magnets for magnetic flowmeters.


Measuring Principle


Faraday's law of induction states that a metal rod moving in a magnetic field induces electrical voltage. This dynamo principle also governs the way electromagnetic flowmeters work.

Measuring Principle

As soon as the electrically charged particles of a fluid cross the artificial magnetic field generated by two field coils, an electric voltage is induced. This voltage, tapped by two measuring electrodes, is directly proportional to the velocity of flow and thus to the flow volume.


The magnetic field is generated by a pulsed direct current with alternating polarity. This ensures a stable zero point and makes the flow measurement insensitive to multiphase or inhomogeneous liquids, as well as low conductivity.


Advantages


  • The measuring principle is virtually independent of pressure, density, temperature and viscosity

  • Even fluids with entrained solids can be metered, e.g. ore slurry or cellulose pulp

  • Wide range of nominal diameters (DN 2 to 3000; 1/12 to 120")

  • Free pipe cross-section: CIP/SIP cleanable, piggable

  • No moving parts, maintenance-free



Applications


There are a number of applications of electromagnetic flowmeters in the Artang range. The Type Aimag S version with a stainless steel sensor can be used in applications with high pressures of up to PN16 and high temperatures of up to 150°C. Furthermore, the Type Aimag C with Alloy C22 electrodes has been designed for applications with aggressive fluids (chemicals) and especially sea water applications.

Electromagnetic Flow Meter

Whereas, Type Aimag A/Aimag D full bore mag flowmeters are designed for water treatment and general purpose applications. Combined with an actuated valve, the complete full bore mag flowmeter Type Aimag H can control high-precision dosing operations and flow measurement in food and beverage or pharmaceutical applications, which is suited to Clean in Place (CIP) applications. 


If you would like any more information about our Electromagnetic Flowmeters please contact us.