Understanding The Magnetic Flow Meter Accuracy

A definition of the term magnetic flow meter may suffice before we can proceed. A flow meter can generally be described as an instrument that is used to measure mass, linear, nonlinear or volumetric flow rate of a liquid. A magnetic flow meter therefore, is a volumetric flow meter that does not have moving parts. It is suitable for any dirty liquid that is conductive or waste water applications.
Essentially, a magnetic flow meter should measure the velocity of liquids that are conductive such as caustic, water, slurries and acids in pipes. Conductive liquids are those fluids that can conduct electricity. It is thus not possible to use this technology to measure either gases because of their gaseous state, or hydrocarbons because of their non-conductive nature.Magnetic flow meters will generally also not work with quite a number of non-aqueous solutions or distilled water.
The principle upon which a magnetic flow meter operates is based on Faradays Law that states that the voltage induced across any conductor as it moves through a magnetic field is proportional to that conductors velocity. It is important therefore that certain factors be put into consideration in order for themagnetic flow meter accuracyto be ensured when making any measurements.

In regard to accuracy, the two main flow meters available are the Wafer-style, (highest accuracy is up to +0.5%) and the insertion style that is used mainly for larger sizes of pipes. A variety of things should be considered when one is making a choice of the flow meter to use. Some of the important questions that need to be addressed in the choice of a magnetic flow meter will include;

Consider the maximum and minimum process pressure.
Consider the maximum and minimum rate of flow of the magnetic flow meter.
Consider the maximum and minimum temperature of the process.
Consider the size of the pipe.
Confirm if the pipe will likely always be full.
Confirm if the fluid is compatible chemically with the wet parts of the flow meter.
Consider if an analogue output is required.
Find out if the slurry or the fluid going through the pipe is clean or abrasive.
Confirm if a remote display or an integral display will be required.
Find out if the fluid is either water based or if it is conductive.

The themagnetic flow meter accuracy shall be determined by all these among other important factors.