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In rather simpler terms, water flow meters are the devices that measure the amount of water flowing through a pipe. With the advancement of technology, there are a number of options to choose from when it comes to choosing from water flow technologies. However, certain things to keep in mind while choosing a water flow meter is to know the maintenance requirements, measurement application and the given budget. Different types of water flow meters have different application benefits, principle of operation and cost of ownership. There are different types of water flow meters and you need to choose the one which is most suitable according to your requirements. Most important thing is need to check whether meter supports online monitoring system through IoT solution. Finding right online monitoring system for water flow meters is pretty easy one. The most famous types of water flow meters are.

  • Ultrasonic Flow Meters
  • Magnetic Flow Meters
  • Mechanical Flow Meters

Now we are going to discuss these in details, so you have a better idea of how these meters work so you can choose according to your requirements.

  • Ultrasonic Flow Meters

It is a type of flow meter which measures the velocity of a fluid with ultrasound, so the volume flow can be calculated. Flow meters use ultrasonic transducers are used by emitting a beam of ultrasound and measuring the velocity along its path. Temperature, viscosity, density are some of the factors that can affect ultrasonic flow meters. Moreover, acoustic properties of a fluid also affect ultrasonic flow meters. Purchase prices can be different but these are usually cost effective and easier to maintain as they don’t use moving parts.

Types of Ultrasonic Flow Meters

Three different types of ultrasonic flow meters are there.

  • Transmission or Contra-propagating Time-Transit Flow Meters
    • In-line (Intrusive or Wetted)
    • Clamp-on (Non-intrusive)
  • Reflection or Doppler Flow Meters
  • Open Channel Flow Meter
  • Time Transit Flow Meters

These flow meters usually measure the difference in the transit time of ultrasonic pulses propagating with and against the flow direction. The time difference is actually the measure for the average velocity of the fluid along the path of the ultrasonic beam. Both the averaged fluid velocity and the speed of sound can be calculated using the absolute transit time.

  • Doppler Shift Flow Meters

Ultrasonic flow meters also use the Doppler Shift which is calculated from the reflection of an ultrasonic beam off sonically reflective materials like solid particles or entrained air bubbles in a flowing fluid or if the fluid is clean, the trubulence of the fluid. It is generally used for gases with sound-reflecting particles, liquids with bubbles and slurries. Blood flow can also be measured using the Doppler Shift flow meters.

  • Open channel flow Meters

The ultrasonic element in the open channel flow metes is usually measuring the height of the water in an open channel. One can determine the flow based on the height by using the geometry of the channel. These meters generally use a temperature sensor as well because the speed of is affected by the temperature in the air.


  • They are low maintenance
  • No moving parts
  • Higher Accuracy
  • Digital and Analog types


  • Can’t be used for heavily contaminated liquids
  • These are significantly expensive than other flow meters
  • Magnetic Flow Meters

A magnetic flow meter is also known as electromagnetic flow meter or a mag meter. It is a transducer that measures fluid flow by using the voltage which induced across the liquid while it is flowing through a magnetic field. The principle of Physics used in the magnetic flow metes is the electromagnetic induction. A magnetic field is created through the metering tube and it results in a potential difference that is directly proportional to the flow velocity perpendicular to the flux lines. These meters generally require a conducting fluid like ionized water and a pipe surface with electrical insulation like a rubber-lined steel tube.


  • Used to measure industrial conductive liquids or slurry
  • Pressure is not lost
  • Large measuring range
  • Measure the influence of other factors as well


  • They have intermediate accuracy
  • They can’t be used in custody transfer applications
  • They can’t work on pure water as they have to use ions for measurements.

Measurement of Flow in Magnetic Flow Meters
Measurement of flow can be calculated by quantifying the bulk fluid movement. It can be measured in many ways but the most commonly used types of measurement in magnetic flow meters are given below.

  • Inferential (Turbine Type)
  • Obstruction Type (Differential Pressure or Variable Area)
  • Positive-displacement Flowmeters as these are the ones which gather fluid in a fixed volume and then the counting is done to the number of times the volume is filled to measure flow.
  • Fluid Dynamic (Vortex Shedding)
  • Anemometer
  • Mass Flowmeter (Coriolis Force)
  • Electromagnetic

All of the methods mentioned above, except for positive-displacement flowmeters, actually work on forces which are produced by the flowing stream because it overcomes a known constriction so the flow is calculated in directly. These types measured the velocity of the fluid over a specific area while tracer methods are used to deduce the flow rate from the change in concentration of a dye or radioisotope for measuring very large flow.

  • Mechanical Flow Meters

These are known to be the most commonly used flow meters as they measure the flow through turbine rotation with a propeller shunt or paddle wheel design. These work by measuring the speed of flowing water running through the pipe and made the turbine to rotate.


These are manual
Easier to use
Economical and cost effective


They may clog up when the water is dirty
Higher Maintenance Cost
Don’t work well with lower flow of water


You can choose the best water flow meter after analyzing your requirements properly. Now, majority of the industry is using the smart water management system and it is recommended to use the IOT based smart technology for conventional water management. Karikala is one of the best IOT based water management systems available in the market.


A well-versed experience in the field of IT with more than 13+ years of expertise in DevOps Consulting, Quality Assurance, Project Management & Outsourcing and predominantly focusing on customer relationships, negotiations, estimations, contact partners, market research and helping small business owners and young entrepreneurs to reach their next level.

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