Float Level Sensors & Switches

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Float level devices use a buoyant magnetic float and sealed reed switches to detect liquid level. They are simple, rugged and need no power in the wetted path, which makes them a first choice for level switching and basic level reading on water, oil, fuel and chemical tanks. Choose a continuous sensor, a multipoint switch or a cable float switch by what the tank has to do.

Float level sensors and switches

Choosing a float level device

What you need	Choose
A live level reading (4-20 mA) or single to multipoint points on an insertion	Float Level Sensor
Several on/off points in one tank, with a material to match the medium	Multipoint Float Switch
Pump start/stop in an open tank, sump or reservoir	Float Level Switch (cable)

Stirred tanks push floats sideways and the reading wanders; a stilling well holds the float in a calm column.

To compare floats with radar, hydrostatic and the other continuous technologies, read our level transmitter types guide.

Cooling tower basins are one of the most common float applications; see the cooling tower water level control guide for setpoints and makeup sizing.

FAQ

What is a float level sensor?

A float level sensor detects liquid level with a buoyant magnetic float and reed switches. The float rides on the surface along a stem; each reed closes at its height to give a switch point, or a reed-resistor chain gives a continuous 4-20 mA reading.

How does a float switch work?

A magnet in the float closes a sealed reed switch when the float reaches it. One float gives a single point; several floats give several points. The medium density must be above 0.5 g/cm³ for the float to stay buoyant.

Request a quote

Tell us the tank height, the medium and its density and temperature, and whether you need a reading, switch points or pump control, and we configure one unit for the application, not a shelf part.