Ultrasonic Flow Meters Vs. Magnetic Flow Meters

Choosing the right flow meter technology is quite critical for your system and your ability to trust the meter’s values will depend greatly on the application. All the different kinds of meter technologies have their advantages and disadvantages. However, attention must be given to the nuances of your system and whatever flows through it.

For instance, when it comes to water applications, there are so many different kinds of technologies which could do the job. But the decision isn’t so simple. You must answer many questions regarding the types of flow meters which would be perfect for your system. In case of water applications, the ultrasonic and magnetic flow meters are popular today.

Ultrasonic Flow Meter:

Ultrasonic flow meters can detect and measure the flow rates without the invasion of flow stream or usage of moving parts. For their functioning, ultrasonic flow meters could use various operation principles such as the transit-time ultrasonic flow meter and the Doppler ultrasonic flow meter. Following are the pros and cons of an ultrasonic flow meter:


  • Ultrasonic flow meters are available in much lower costs of installation. There would be no need to shut your system down and even your piping would require no alteration.
  • Lesser moving parts mean lesser maintenance required.
  • They can be used with corrosive solutions as well.
  • These flow meters are rather insensitive to variations in viscosity, temperature, density or pressure.
  • They are available in a diverse range of communication protocols, i.e. Transit Time


  • There could be some errors or shifting of flow signals due to unknown internal piping variables.
  • Problems can arise from the pitting, scaling and fouling which might occur eventually in the older piping systems.
  • There may be some air space in the pipe which could affect the accuracy of ultrasonic flow meters.

Magnetic Flow Meters:

Magnetic flow meters are used to measure the flow rates by using Faraday’s Law of Electromagnetic Induction according to which, a magnetic field is produced by running current through a coil signaling the flow tube. After this, the conductive liquid/media creates a voltage while passing through the magnetic field and the flow tube. The electrodes can detect and measure the voltage that is resulted while the fluid passes through the flow tube. With increasing velocities, the voltage also increases and this signal is eventually changed to volumetric flow. Such flow meters are particularly created for systems which move conductive fluids like acids, water, slurries and caustic liquids.


  • Magnetic flow meters have no flow hindrances or moving parts.
  • They are relevant to all flow profiles and don’t need a straight run.
  • They can respond to rapid changes in flow well.
  • They are applicable to liquids that have heavy particulates.
  • They have a life span of 75 years.


  • The air space in the pipes of magnetic flow meters may affect their accuracy.



Before coming up with just the right flow meter, you must consider both types of flow meters, that is, the ultrasonic and the magnetic flow meters along with their pros and cons.

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