Level Measurement · Glossary

What is a Displacer Level Transmitter?

buoyancy basedLevel Measurement

A displacer level transmitter measures level from the buoyancy force on a heavy cylinder partly submerged in the liquid.

Displacer Level Transmitter Explained

The displacer is heavier than the liquid and does not float. As level rises, buoyancy reduces its apparent weight, which a torque tube or spring measures.

Displacers are proven for level and interface in high pressure vessels, but are density dependent and need a chamber or stilling well in turbulent service.

Displacer Level Transmitter Formula

F_b = ρ × g × A × h_sub

F_b	buoyancy force (N)
A	displacer cross section area (m²)
h_sub	submerged length (m)

Example: Displacer 0.0025 m² area, 0.5 m submerged in water: F_b = 1000 × 9.80665 × 0.0025 × 0.5 ≈ 12.3 N.

Calculators for Displacer Level Transmitter

CalculatorDisplacer Level CalculatorFree online calculator with formula and worked example.CalculatorFloat Buoyancy CalculatorFree online calculator with formula and worked example.CalculatorInterface Level CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadLevel Transmitter Datasheet Template in ExcelFree download in Excel and PDF.

Frequently Asked Questions

What is a Displacer Level Transmitter?

A displacer level transmitter measures level from the buoyancy force on a heavy cylinder partly submerged in the liquid.

Float or displacer?

A float rides on the surface; a displacer stays nearly in place and measures force. Displacers give a continuous signal over their length.

Why does the displacer length matter?

The measuring range equals the displacer length.

Learn more on the blog

Types of level transmitters

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

Read Full Article

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