Flood Prevention Using A Level Float Switch

Stainless Steel Vertical Float Switch GIF

Float switches are used across a variety of industries for flood prevention, but it’s important to choose the right level float switch. Depending on the application of the device, the float switch you choose can make a big difference.

A tank that is used for flood prevention.

How Do Float Switches Work?

The ultimate purpose of a float switch is to open or close a circuit as the level of a liquid rises or falls. Think of a float switch like a light switch, opening and closing contacts to control whether or not signal current can pass through.

There are two types of float switches, float switches that are Normally Closed and float switches that are Normally Open. Normally Closed means current is flowing whereas, Normally Open means that it is not. When the level float switch is down, this means it is in its normal state. This is either resting on its cable or float stop.

Normally Closed float switches usually function as high-level switches, meaning that they turn OFF filling pumps when the liquid lifts the float and breaks the circuit. Normally Open float switches typically function as low-level float switches. An example of this would be when a Normally Open float switch turns OFF an emptying pump when the liquid falls below the level of the level float switch.

If a certain liquid level must be maintained, a level float switch is great for automatic pump control and alarms. One of the most common uses of a float switch is for flood prevention.

For instance, if a tank gets too full, it runs the risk of overflowing. However, using a level float switch, a pump can automatically be turned on or off depending on the level of the tank.

But what happens if you choose the wrong type of float switch to work with your liquid level controller? If you are using an automatic pump control to manage liquid level(s), the wrong level float switch could send inaccurate or erroneous signals, turning your pumps on or off at the wrong time. This creates flooding, pump failure, or both. As a result, damage, repair costs, and loss of business are all possible consequences of flooding and we know that you don’t want to have to deal with that pain. We are here to help you determine what type of level float switch is best for your business and flood prevention!

Choosing a Float Switch for Flood Prevention

There are a few factors that you will want to consider when choosing your level float switch. The location, tank size, and liquid temperature all need to be considered when purchasing a device. If your liquid level controller is not made to the specifications that you need, it’s much more likely that your automatic pump control will fail, resulting in flooding.


Not all level float switches are made to withstand high temperatures. If the liquid you are working with is kept at extreme temperatures, you will need to consider this when choosing your float switch. For instance, our Stainless Steel Horizontal Float Switches and Vertical Float Switches are able to operate in temperatures up to 500° Fahrenheit. Make sure that the vertical float switches and horizontal float switches you are using are able to operate under the temperature and conditions of the material for the best flood prevention.

The FS-400 stainless steel vertical float switch.

Built-In Hysteresis

Do you need a controller to add logic to the on/off equation of your horizontal and vertical float switch? If so, this will affect your decision as well. If a pump is controlled by a switch with no logic, and the level has stopped right at the float, any ripple on the surface will cause the float to bounce up and down. This bouncing will turn the automatic pump control on and off, burning out the motor super quickly. However, a control with hysteresis, as offered with the Kari Multi-Level Cable Float Switch, will tell pumps to turn off at one level and turn on only at another level. You don’t want to burn your motor out, effectively stopping the pump from working and resulting in a flood.


When determining which level float switch to purchase, think about how many switch points you will need. Some float switches are made with a single switch point, mainly used for simple alarming applications. These types of traditional float switches are usually the least expensive, but you may need to spend more in order to accommodate your application. You might need a level float switch that instead has four switch points, or even seven.

Take a look at APG’s Kari Multi-Level Cable Float Switch, which provides pump control with hysteresis and alarms.

kari multi-level cable float switch

Or the FLE/FLX for even graduated, point-to-point level monitoring.

The FLE/FLX Stem Mounted Multi-Point Level Switch with point-to-point level monitoring. src=

Whatever the need is, first determine the necessary amount of switch points you need before purchasing a level float switch for flood prevention because each one will offer something unique.


Another factor to consider when purchasing a level float switch to act as a liquid level controller is the location you are working in. If you are working in a hazardous location, you will need a float switch that is certified for that certain location. The CSA defines hazardous locations in classes and divisions for North America and it is important that the float switch you are using has been cleared for the specific hazardous location you are working in.


So, as you can see, there are many factors to consider when purchasing a level float switch. You want to ensure that you are getting the right level float switch for your location, application, and needs. If you don’t take the time to find the right level float switch for you, you run the risk of floods. And we all know floods are damaging and expensive, so it’s best to take all the necessary precautions for flood prevention.

Learn more about the many different types of float switches APG Sensors has available, and find the perfect one for you. If you need help deciding which level float switch would be best, speak with one of our engineers today to figure out which float switch is best for the job you need finished!

If you have any questions about our float switches or any of our other products, contact us today.

Explore Float Switches

Have a Question?

You can contact us directly by clicking the link, connecting with us on social media, or sending us a chat during business hours.