Water flow sensor: types and it’s applications

A water flow sensor is a device that measures the water flow rate and calculates the water amount flowing inside a tube or a pipe. The unit of measurement is usually in cubic meters or liters per hour.

The accuracy level, cost, applications, advantages, and disadvantages of each water flow sensor type determines the best type of water flow sensor to use. Below are some of the commonly used types of water flow sensors and their applications.

1.Paddlewheel flow sensor

A paddlewheel is a type of water flow sensor which measures the flow rate of water-like fluids through generating a voltage and frequency using a blade and a rotor of the paddlewheel flow sensor, which is always perpendicular to the flow. Embedded magnets enhance all these from the rotating impeller.

     Applications of paddlewheel flow sensor

i)Used in the chemical industry.
ii) Used in the food and beverage industry.
iii) Used in the oil and gas industry.
iv) Used in the treatment of water.
v) Used in the pharmaceutical industry.


i)It provides a high level of accuracy since less force is required to turn the wheel due to a small number of blades.
ii) Paddlewheel flow sensors are cheaper than other water flow sensors.
iii) It has a repeatability form of measurement.
iv) It is smaller in size hence easily portable.
v) A Paddlewheel flow sensor can adjust the flow valves and measure corrosive liquids.


i)Presence of hair may lead to inaccurate results.
ii) Paddlewheel flow sensor is sensitive to new objects
iii) The rotation of the paddlewheel may make it require regular maintenance, which may be costly.
iv) It requires a straight pipe for operation.

2. Ultrasonic flowmeters

Ultrasonic flowmeters use sound waves to measure the liquid velocity flowing in a water pipe. When the fluid is flowing, the Doppler effect makes the frequency of the waves not be identical. When there is no flow, the indication of the frequent wave from the fluid is always similar. Applications of ultrasonic flowmeters i)Ultrasonic flow meters are used as an alternative for electromagnetic and vortex flow meters.
ii) Used in measuring dirty liquids wastewater.
iii) Used to measure the liquids’ velocity and to analyze the flow volume.
iv) Ultrasonic flow meters are suitable where chemicals are compatible. Advantages
i)Helps to conserve energy.
ii) Liquid flow path cannot be blocked.
iii) There are no risks of leakage.
iv) The liquid can flow in two directions.
v) It provides a highly accurate measurement.
vi) It is simple to install and maintain. Disadvantages
i)Ultrasonic flow meter has a complex designation
ii) It is more expensive to purchase than other water flow sensors.
iii) It cannot measure rusted concrete and cement pipes.

3. Positive displacement flow meters

A positive displacement water flow sensor provides a direct measurement of the liquid volume flowing in a pipe. It forms a trapped pocket of fluids between the components rotating in the chamber. The velocity of the rotational rotor is always proportional to the flow rate. Applications of positive displacement flow meters i)Used in the food and beverage industry.
ii) Used in the pharmaceutical industry.
iii) Used in the water and wastewater industry.
iv) Used in the chemical industry.
v) Used in the oil and gas industry.
vi) Used in the power industry.
vi) Used in the metal and mining industry.
vi) Used in the paper and pulp industry. Advantages
i)Positive displacement flow meters require low maintenance.
ii) They are capable of measuring fluids under high pressure and temperature.
iii) They are available in both mechanical and electronic versions
iv) Positive displacement flow sensors provide a high accuracy level. Disadvantages
i)They do not measure liquids or fluids with large particles.
ii) Positive displacement flow sensors can cause pressure drop.
iii) It cannot measure fluids where there are large pockets of air.

4. Magnetic flowmeters

Magnetic flowmeters work in line with Faraday’s law of magnets which states that when a conductive medium travels through a magnetic field, it leads to the voltage generation, which is proportional to the medium, the length of the conductor, and the density of the magnet field. Applications of magnetic water flow sensors.
i)Used in the water and wastewater industry.
ii) Used in food processing industries.
iii) Used in the measurement of powder, slurries, coal, sewage, and other chemicals.
iv) Used in the paper and pulp industry.
v) Used in the chemical industry. Advantages i)Magnetic flowmeters can handle the low liquid flow.
ii) They can measure the flow rate in two directions.
iii) There is nothing that can obstruct the flow used in sewage, mud, and wood pulp.
iii) It has no head loss in pressure.
iv) They cannot be affected by variation in temperature, pressure, density, and viscosity. Disadvantages i)The accuracy level is low.
ii) They can only measure fluids with good electrical conductivity. Conclusion Water flow sensors are vital in many applications. The cost and type of application determine the type of water flow sensor to be used. You should how every water flow sensor operates for you to obtain the most accurate results.

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