How does a Water Flow Sensor work?

A water flow sensor plays a very vital role in automatic systems. Many residential and commercial buildings require a huge amount of water supply. Even industrial plants need a lot of water. To promote good water usage in those areas, you need to monitor the water supply and the amount being used by measuring the flow rate.

Want accurate water flow rate measurement? You’ll have to buy an appropriate water flow sensor. Besides using a water flow sensor to measure water flow, the device can be used in DIY coffee machines and automatic water heater control.

 Once you install a water flow sensor in a pipe or water source, it will help to measure the rate of flow through the pipe and tell the total amount that passes through in cubic meters or terms of liters. 

Working principle of a water flow sensor 

Any water flow sensor you will come across is made up of various components which work together to help determine the flow rate. These components include a hall-effect sensor, a water rotor, and a copper body. 

The water must get into the valve through the inlet to measure the flow rate and get out through the outlet. As the water goes through the valve, it makes the rotor rotate. You can observe any change inflow based on the speed of the rotor. The rotating rotor produces pulses, and the flow rate increases or decreases. 

Pulse signals produced by the moving rotor are recorded by the Hall Effect sensor, which helps to determine the flow rate of the liquid being monitored. The rotation of the rotor induces a voltage difference in the conductor. That voltage difference induced is crosswise to the electric current.

So, when the mobile fan is rotated due to the effect of water that flows in, the rotor will rotate, inducing the voltage. It’s that induced voltage that is measured by the Hall Effect sensor. The results are then displayed on the LCD of your water flow sensor.

You may interface your water flow sensor with microcontrollers. But you’ll need a microcontroller board to help in processing. In addition, there will be a hallo-effect sensor and then an LCD. A breadboard connecting wires is also much if you will want to interface your water flow sensor. Once you’ve all those connected, you can place your sensor at the pipe’s opening or the source of the water.

Don’t forget that the water flow sensor has three wires. You’ll use the red wire for connecting with supply voltage. The black wire is applied to connect to the ground while the yellow one collects signals from the hallo-effect sensor. For effective functioning of the water flow sensor, you need a supply voltage of about 5V-18V of DC. 

You’re free to use a water flow sensor on dirty, clean, warm, cold, and even hot waters. Many water flow sensors are available in the market and are of different diameters. Besides, they differ in terms of flow ranges.

Water flow sensor applications

With a water flow sensor, you can measure water flow rate by displacement or velocity. It doesn’t matter whether you are dealing with water or milk in the dairy industry. You can always rely on this device for the most accurate flow rate results.

For monitoring water-like fluids, you can use a paddlewheel flow sensor. It’s a cost-effective solution when it comes to flow metering issues. A paddle wheel flow sensor is also compact and only needs little energy to operate. You can use this type of water flow sensor on an array of fluid types.

If no straight pipe for the inlet, you may use a positive displacement water flow sensor. This device helps measure flow rate by establishing the volume of fluid that passes through the meter per unit of time. As the liquid flows, it moves the rotating components directly, and the speed of rotation is proportional to the fluid flow rate. The positive displacement flow sensor is the best to use when handling very viscous liquids.

When working with wastewater and dirty water that is conductive, choose a magnetic water flow sensor. These sensor devices have a coil meant to induce a magnetic field in the monitored fluid and then apply them for measuring the voltage induced. The results of the induced voltage give the flow rate of the liquid.

What to consider when buying a water flow sensor

Since there are many types of water flow sensors, you’ll have to consider various factors before buying to ensure you get the right device.

  • The type of fluid to be monitored
  • Cost of the water flow sensor
  • Accuracy required
  • Type of the display needed
  • Availability of power
  • Flow range
  • Properties of the fluid to be monitored
  • Signal output required 
  • An acceptable amount of pressure loss 


Get an easy-to-use and cost-effective water flow sensor! It will help to determine the flow rate of the monitored liquid with a high degree of accuracy. But buying any particular water flow sensor ensures you understand how each functions since you’ll find many of them in the market. That way, you can get the most suitable device.





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