Water flow switch: how does it work?

A water flow switch is a machine that system operators use to detect the water movement in a pipe or a tube. The presence of fire in the flowing water is to protect against fire. Due to this, the water flow switch is known to be a mechanical to electric fire alarm input device since it alerts the fire alarm on the flowing water in the pipe under the sprinkler systems.

The water flow switch works by employing a physical paddle or ultrasonic connection to the channel directly where water and other liquid substances pass through. The flow rate in the transducer is shown by the speed of the moving paddle, where the transmitter takes the measurement information and converts it to a signal reading.

The water flow switch comes in many different types. This article will explain some of the classes with their working principles, benefits and limitations.

Types of water flow switch

1.Inline flow switches

Inline flow switches are a type of water flow switch that works after a permanent installation is an integral part of the whole system. Unlike other water flow switches, they do not use a paddle in sending the signal to the transmitter outside the pipe. Instead, they detect the flow rate internally.

Benefits of inline water flow switch

i)Inline flow switches always condition the liquid flow automatically after the installation.

ii) Inline flow switches only require short straight pipes to work well and provide accurate results.

Limitations of inline water flow switches

i)Inline water flow switches are expensive to purchase and install.

ii) Inline water flow switches require high maintenance costs.

2. Water pump flow switches

Water pump flow switches work by detecting a gravitational movement of the water flow rate in the pipe system. It sends an alarm to the pump, thus lowering or raising the water pressure inside the system.

The flow switches have a designation structure that automatically adjusts the volume and speed of the electric transfer in the water pump connected to the liquid flow system.

Benefits of water pump flow switches

i)Water pump flow switches help in water treatment processes.

ii) They help in the cooling of water equipment.

iii) They regulate the transfer of liquids in the pipes.

iv) Water pump flow switches help in Plumbing activities.

v) They prevent the dryness in water pumps when there is no supply of water.

Limitations of water flow switches

i)Inability of the pump to dry may destroy some parts of the pump.

3. Paddle water flow switches

The working condition of the paddle water flow switches depends on the paddle, also known as the physical probe where the operators hang them on the operating pipe or pump in which the liquid or any other substance is flowing at.

The variation of pressure and speeds of the flowing liquids determines the flow rate in the transmitter, which sends the signal and converts the measurement into a reading section.

Benefits of paddle water flow switches

i)Paddle water flow switches provide reliable and accurate results in flow rate measurements.

ii) Paddle water flow switches create a constant reading session where the measurement is always preserved.

Limitations of paddle water flow switches

i)Paddle water flow switches require regular maintenance, which may be of a high cost.

ii) Paddle switches have moving parts that may be affected by wear and tear during the flow measurement.

iii) Paddle water flow switches are sensitive to new objects and build up in residue, thus limiting the flow rate in some things.

4. Sprinkler’s flow switches

Sprinkler’s flow switches detect when a liquid substance or water travels through a sprinkler pipe, thus increasing the flow rate by showing the triggered sprinkler. The system is the most commonly used in automotive fire sprinklers applications.

The system sends out the signal to the fire department operators to investigate any problem that may lead to the destruction of the water pipe or pump.

Benefits of sprinkler flow switches

i)Sprinkler’s flow switches do not send false signal detection on the flow rate measurement.

ii) The changes in pressure inside the pipe do not affect the signal transfer.

Limitations of sprinkler flow switches

i)The system takes a lot of time to send the signal to the transmitter.

ii) Sprinkler flow switches only send emergency signals after detecting a continuous flow of a liquid after some time

5. Magnetic water flow switches

Magnetic water flow switches usually apply the law of Faraday in electromagnetic induction, which states that the voltage introduced in the following liquid is proportional to the movement speed when water or liquid substance is flowing in the field of magnets.

The volume and movement speed are given by the water traveling through a magnetic field where the electrical sensor provides the reading information that sends a signal action to the transmitter.


Magnetic water flow switches help in the treatment of wastewater.


Magnetic flow switches are only limited to measure the flow rate of conductive materials.


Knowing the various types of water flow switch will help you choose the best for your application. If you are confused about which one to use, you should consult engineers or system operators to help you out.