float switch

What is a Float Switch and How It Works?

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What is a Float Switch and How It Works?

If you ever wonder what a float switch is and how it works, this article will guide you in detail about it.

A float switch is a device that detects the level of a liquid in a container. It is a mechanical switch placed on the top of the fluid and floats on it. When the liquid goes up and down, it measures the level of the liquid. The float switch is used to control devices like valves and pumps. They are also used in alarms to notify the users. They are very reliable, and you can use them for different purposes. They are also considered to be cost-effective.

How Does a Float Switch Work?

A float switch is a mechanical device that floats over the liquid and determines the level of liquid in a tank or container. When a liquid slowly goes up, the switch shows an upward movement vertically and opposite when the fluid level goes down. These switches have a trigger attached to it. When the liquid starts moving, the trigger activates the circuit by allowing an electric current to pass through the connected device.

Switching Method of a Float Switch

Float switches use a switching method when triggers become active. If the magnet is close to the circuit, then the switch is closed, and the circuit is complete. As a result, an electric current starts to flow.

Similarly, if the magnet moves to the opposite side of the switch, the switch is open, and the circuit is incomplete. As a result, no electric current will flow. The switch has its switching capacity, which means it has a maximum switching voltage and current. Make sure that your switch doesn’t reach its maximum switching limit.

The liquid in the container will control the angle of the switch. The angle of the switch controls the position of the magnet. Magnet’s position inside of the switch determines its movement. The float switches installation has two points one is a fixed point, and the other is the counterweight. The internal mechanical switch will change its position to open and closed depending upon the movement of liquid.

The float switches have applications in tanks where one side of liquid is higher than the other. The switch in the liquid will show the result when the floating body will rise. This causes the magnet to move up or down as the switch opens or close. If the circuit is closed, it will signal the pump to stop pumping water into the tank.

When the liquid level decreases, then the switch goes downward, and the magnet moves away so that the circuit will remain open and no current will flow. The open-circuit gives a signal to the pump to remain on and pump more water into the tank. Similarly, there are many applications of float switches. The above setup also works when one side of the liquid is lower than the other. This depends upon the wiring of the switch.

The function of External Counterweight

Float switches have external counterweights. There is a cable that links the counterweight to the float switch. These counterweights create an angle with the water level. Many cable lengths depend upon the functioning of the switch. You can use both maximum and minimum cable length. The construction of the switch is different for each size of cable. It depends upon the function if you want to start or stop the flow of liquid. The primary function of external counterweights is to make a suitable angle with the level of water.

Wiring in Float Switch

The wiring of the float switch is important for its functioning. Proper signals are required so that switch can work properly. Electric signals are responsible for the opening and closing of the switch. For different switches, the operation of the opening and closing of the switch can be changed. Before using them, always read the instruction manual so that you know about the wiring.

There are two types of Wirings commonly used in a float switch.

  • Normally closed float switch- A normally closed float switch is when the electrical circuit is closed. The circuit is closed in the down position and opens in the up position.
  • Normally open float switch- A normally open float switch is when the electric circuit is open. The circuit is opened in the down position and closes in the up position.

Types OF Float Switches

There are many types of float switches available in the market. You can buy according to your requirement.

1. JPM Series

JPM series switch is a tilt level switch that has a very heavy body. This is free of irregularity and doesn’t have an external counterweight. This series switch rotates around itself when it is dipped in water. This switch is most suitable when there is turbulent water and is also used for wastewater. Typically, the JPM series is used in pairs to enable its functioning of filling and emptying. This switch can enable two modes. One usually is open, and the other is normally closed.

2. KPM Series

The KPM series switch is most common due to its smooth functioning. It is used for clean water. KPM series uses an angle of 45 degrees to close and close the electric circuit. The cable length tells the level of liquid at which the switch will perform its function.

3. MPM Series

The MPM series is a switch that has a double liquid-proof chamber giving the switch its strength. The switch is highly reliable. It has protection on the inside, although it is small in size. Sometimes it is used in sewage water if its size increased. MPM series uses an angle of 45 degrees to close and close the electric circuit. The cable length tells the level of liquid at which the switch will perform its function.

Applications of a Float Switch

Float switches are used to monitor and control the level of a fluid. It has applications in many industrial and residential areas. Float switches are connected to the pump, solenoid, or some valve, etc. Sometimes they are connected to the alarms to notify the user. They are available in various designs and types. Different designs are used for other purposes. Some of the applications are:

  • For water level control, these switches are used by refrigerants and air conditioning.
  • Float switches are used in sewage pits. Those switches are called sump pump float switches. They can detect the rising water level, and a switch is used to level it and initiate a pumping action.
  • The beverage industry also uses them for filling and emptying the tanks containing beverages.
  • Water tank float switches are used in controlling the water level. They control the water level for rainwater, wastewater, and have other sewage applications. The pump acts by on and off switch.
  • To monitor the water level of the washer, they are used by industrial washers.


A float switch is a switch used to monitor a liquid’s level in a tank or container. They are available in markets in different shapes and sizes. Depending upon their Variety, they perform different functions. The two main wiring system used in it usually is open wiring and normally closed wiring.

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