How a Floating Switch Works

With a float switch, you have a device that is designed to detect the level of liquid in a tank. There are several different types of float switches and they can be used for various purposes. Commonly, they are used for reading the level of liquid in a tank and providing feedback or they can be set up to engage or disengage a response when the amount of liquid rises or falls to a determined level. Additionally, there are multistage float switches that can provide feedback or perform different functions as the level of liquid rises or falls within the tank.

How does a Floating Switch Work?

Most float switches are the type that just open or close a circuit as the level of liquid in a tank rises or falls. With the more common reed switch, the device will have two electrical contacts sealed in a glass casing. The two leads will be close within the housing, but they will not be touching. The housing with the glass leads will be mounted at a point in the tank to determine the liquid level that triggers the response.

In the liquid, you then have a magnetic float. As the level of the liquid in the tank rises or falls, the float will come closer to the leads. When the float is in range, the leads become magnetized and then come together, completing the circuit. When the liquid level changes in a way that brings the float away from the electrical contacts, they separate and the circuit is broken.

Float Switch Configurations & Functions

Floating switches can be set up in various configurations to allow them to perform different functions. A switch can be made to engage a piece of equipment or a function as the liquid level rises or falls, they can be configured to open a circuit when the float nears, they can be set to close the circuit as the float nears and they can be configured to trigger a response at different tank levels depending on the purpose.

An example would be a float that rises with the liquid to trigger a switch that turns on a pump. When the pump has removed enough of the liquid, it can then disengage the pump. Conversely, a float could be configured to float in liquid that needs to maintain a certain level. As the level drops, the float will eventually come in range of the switch. This could then trigger the opening of a valve to refill the tank to a predetermined level.

These are just a few of the more simple functions that a float switch can perform. Depending on the purpose and the design of the switch, they can be applied to much more complex tasks. Understanding the desired application of the switch will help to determine the right type of float switch that should be used and the configuration.