Flow Meter Working Principle, Mag Meter, Mechanical, Vortex, & Ultrasonic Flow Meter

(Last Updated On: November 3, 2020)

Flow Meter Working Principle:

Flow Meter

flow meter:- There are many types of flow meters available for use in industrial automation depending on the product to be measured whether it’s liquid or gas; some basic principles apply to how the meters work.

How Flow Meter Work Or Mag meter?

Magnetic flow meter:

Flow Meter

The measured liquid must be water-based or conductive, this makes the Mag meter a great choice for wastewater or process water that is considered fouled or dirty.


Mag Meter Or Magnetic Meter Or volumetric meter:

Flow Meter

The Mag meter or volumetric meter that has no moving parts, this is ideal for those areas where you wouldn’t want to be exposed to the measured liquid while working on the meter. The way a Mag meter works is based on a formula called Faraday’s formula.

Firstly again the liquid must be conductive, a voltage is measured that is dependent on the average velocity of liquid Times the strength of the magnetic field times the length of the conductor this is the distance between the electrodes.

Flow Meter

This is all that wonderful science stuff you know like E = MC2 it’s Einstein’s theory of relativity we’ve all heard of or seen the equation many of us don’t know what it means. However the people that do know how to use the equation have used it for both benefit and detriment.

We don’t need to know Faraday’s formula to use a Mag meter necessarily even need to know what that formula is. We just know that whoever invented the Mag meter used the formula to produce a signal voltage that can be measured by your automation process.

Flow Meter

Flow Meter

While Mag meters work based on Faraday’s formula other flow meters work in different ways.



Mechanical Flow Meter:

A mechanical flow meter has some moving internal parts which may not fit with specific applications such as dirty water that carries large particles that may cause damage or obstruct the internal parts.

The mechanical flow meter has a rotational device inside such as a paddle wheel or propeller.

Flow Meter

Liquid flowing through a pipe causes the rotation of the internal paddle which creates a flow rate that is proportional to the rotational speed of the internal paddle.

Flow Meter

The mechanical flow meter is easier for laymen to understand, pedaling a bicycle slowly moves you slowly while pedaling quickly will move you much faster. Direct correlation between how fast the pedals rotate their four wheels and how fast you go down the road no formula needed just pedal faster move faster.

Same principles, the internal paddle the faster it’s rotating, the more flow going through the pipe which in turn sends a graduated signal to your PLC. That’s the simplified version but there are other factors that the manufacturer takes care of for you piping size and water temperature etc all go into a formula that will correlate the rotational speed with a unit measurement such as gallons per minute. Yet still there are other types of flow meters.

Vortex Flow Meter:

Flow Meter

There’s vortex flow meter which measures vortices essentially a sensor tab will Bend and flex from side to side as the vortex passes the bend and flex action will then produce an output frequency that is proportional to volumetric flow.


Ultrasonic flow meter:

Flow Meter

Principle behind these meters is that an ultrasonic signal is transmitted downstream or in the direction of the flow while another signal is transmitted upstream. the Delta or differential time is used to calculate the velocity of the liquid that velocity is then used to calculate the volumetric flow through the pipe.

Flow Meter

As you can see there are many types of flow meters for various applications. You don’t really need to know the formulas and science behind the scenes. But hopefully we have given you some idea of how a flow meter works you.

Flow Meter


Related Article:

Arduino and Magnetic Flow meter based liquid volume measurement.

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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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