Level Measurement · Glossary

What is a Float Level Switch?

Q: What is a Float Level Switch?

A float level switch uses a buoyant float that rises and falls with the liquid to operate a contact at one level.

Q: How is a float switch tested?

By raising and lowering the actual level, or by lifting the float in a test chamber, and confirming the signal at the control system.

Q: Can float switches be used for pump control?

Yes, often with two floats or a wide angle cable float for start and stop.

point levelLevel Measurement

A float level switch uses a buoyant float that rises and falls with the liquid to operate a contact at one level.

Float Level Switch Explained

The float moves a magnet that operates a reed switch or snap switch through a non magnetic wall, or tilts a cable float. It gives an on or off signal at a set level.

Float switches are simple and need no power, but can stick with sticky or dirty liquids and need regular functional testing.

Float Level Switch Formula

Float works if ρ_float < ρ_liquid

ρ_float	average float density
ρ_liquid	minimum liquid density

Calculators for Float Level Switch

CalculatorFloat Buoyancy CalculatorFree online calculator with formula and worked example.CalculatorSump Pump Cycle Time CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadLevel Switch Testing ProcedureFree step by step procedure, Word and PDF.

Frequently Asked Questions

What is a Float Level Switch?

A float level switch uses a buoyant float that rises and falls with the liquid to operate a contact at one level.

How is a float switch tested?

By raising and lowering the actual level, or by lifting the float in a test chamber, and confirming the signal at the control system.

Can float switches be used for pump control?

Yes, often with two floats or a wide angle cable float for start and stop.

Learn more on the blog

Types of level transmitters

A practical guide on instrumentationblog.in with more detail on float level switch and how it is applied on real plants.

Read Full Article

More Level Measurement Terms

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