Selection of flow meter for water with high amount of scaling


In one of my applications I wanted to use a clamp-on ultrasonic flow meter (transit time type) but in the pipe I found a lot of scaling. So I need to know which type of flow meter is good to use in this case.

I wanted to use a non-intrusive instrument as it is a running unit and getting a shutdown is difficult. So please suggest which is the best type of flow meter to be used as I feel transit time sensor will not work properly for this particular case.

If at all we have to use intrusive methods only, then please which is the best meter/sensor with minimal tapping to be created because inline full bore instruments installation is not possible in this unit.


1 Like

i understand your concern you have following options left;

Magnetic Flow Meter

Magnetic flow meters measure the speed of a fluid passing through a pipe using a magnetic field to measure the volumetric flow. They are based on the principle of Faraday’s Law of Electromagnetic Induction, according to which liquid generates voltage when it flows through a magnetic field.

The more rapid the fluid flow, the more the voltage generated. The voltage produced is directly proportional to the water movement; the voltage signal is processed into the volumetric flow rate by the electronics.

Since the magnetic flow meters show an intermediate accuracy, they are not suitable for custody transfer applications and cannot be used to measure pure water as there are no ions to measure.

Magnetic Flow Meter

Thermal mass flow Meter


  1. Easy to install
  2. No moving parts
  3. Weather resistant and surge protected
  4. Milliamp output for Totalizer
  5. Digital pulse output for SCADA/PLC/CONTROLLER for Air flow meter
  6. User-configurable scaling, filtering and units of measure
  7. Optional wired and wireless outputs for networking

By-pass scheme




Gas flow meter DP type
Installed with Senior Daniel orifice fittings.
Fb2200 emerson flow computer


I used magnatic flowmeter, so I suggest it.


Hi @mehta2155

Greetings and thank you for your reply. As suggested by you, the idea of using a Insertion type Magnetic flow meter had come to my mind but I am doubtful about if the high scaling property of water effects/influence the sensor.

So can you please let me know does that really effect this type of sensor if so how/what kind of effect does it have.

Thanks & Regards.

Thinking logically scaling is not going to effect emf induced in magnetic flow meter; concerning the basics of magnetic flow meters works on the principal that emf induced is directly proportional to flow of conducting liquid. There are almost no problems with electromagnetic types, but if a thick layer of scaling attaches to the inside of the flow path, eventually the flow meter could become unable to sense the voltage that has been generated and maintenance would be required.
At the end kindly clean pipe to avoid further scaling.

The accuracy and reliability of magnetic flow meters, which play a key role in flow rate measurement, have become increasingly higher thanks to advances that have been made in electronics and the development of lining materials and manufacturing methods. This has led to the establishment of magnetic flow meters’ position across a wide range of applications.

Lining in the context of electromagnetic flow meters refers to applying resin or other alternative materials to the inner walls of a detector’s measurement tube (metal pipe).


Lining is important in order to efficiently detect generated very low electromotive force levels and ensure corrosion and abrasion resistance to the fluids being measured. The material for lining is selected according to the type of fluid to be measured.

Magnetic Flow Meters Lining Materials.pdf (169.6 KB)

source: yokogawa

Thank you for the opinion shared. its really helpful for me.