Flow Measurement · Glossary

What is a Vortex Flow Meter?

liquid, gas and steam velocityFlow Measurement

A vortex flow meter counts the vortices shed from a bluff body; their frequency is proportional to flow velocity.

Vortex Flow Meter Explained

A bar across the pipe sheds vortices alternately from each side, like a flag waving in wind. A sensor counts them. The ratio of frequency to velocity is set by the Strouhal number, which is nearly constant over a wide Reynolds number range.

Vortex meters suit steam, gas and clean liquids. They need a minimum Reynolds number and velocity, and are sensitive to pipe vibration and upstream disturbances.

Vortex Flow Meter Formula

f = St × v ÷ d

f	shedding frequency (Hz)
St	Strouhal number, about 0.2
v	velocity (m/s)
d	bluff body width (m)

Example: St = 0.2, v = 3 m/s, d = 0.02 m: f = 30 Hz.

Calculators for Vortex Flow Meter

CalculatorVortex Flow Meter CalculatorFree online calculator with formula and worked example.CalculatorReynolds Number CalculatorFree online calculator with formula and worked example.CalculatorK Factor CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is a Vortex Flow Meter?

A vortex flow meter counts the vortices shed from a bluff body; their frequency is proportional to flow velocity.

Why is vortex popular for steam?

No moving parts, high temperature ratings and direct volumetric measurement; with pressure and temperature it gives steam mass flow.

Why does pipe vibration affect it?

The sensor detects small pressure or force pulses, and vibration near the shedding frequency can be counted as false flow.

Learn more on the blog

Types of flow meters

A practical guide on instrumentationblog.in with more detail on vortex flow meter and how it is applied on real plants.

Read Full Article

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