Level Measurement · Glossary

What is Bubbler Level Measurement?

purge gas back pressureLevel Measurement

Bubbler level measurement pushes a small gas flow out of a dip tube; the back pressure equals the liquid head above the tube end.

Bubbler Level Measurement Explained

Air or nitrogen bubbles slowly out of the bottom of the dip tube. The pressure needed to push it out equals the hydrostatic head, which a transmitter at the top measures.

Only the tube touches the liquid, so bubblers suit corrosive, dirty or radioactive liquids. The purge flow must be small and steady.

Bubbler Level Measurement Formula

h = p_back ÷ (ρ × g)

p_back	gauge back pressure
ρ	liquid density

Example: 19.6 kPa on water gives about 2.0 m above the tube end.

Calculators for Bubbler Level Measurement

CalculatorBubbler Level CalculatorFree online calculator with formula and worked example.CalculatorPressure to Level CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is Bubbler Level Measurement?

Bubbler level measurement pushes a small gas flow out of a dip tube; the back pressure equals the liquid head above the tube end.

Why keep the purge flow low?

Flow causes a pressure drop in the tube that reads as extra level.

What if the dip tube blocks?

Pressure rises to the supply pressure and the level reads full. Some systems use a periodic blow down.

Learn more on the blog

Hydrostatic level measurement

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

Read Full Article

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