Flow Measurement · Glossary

What is a Pitot Tube?

point velocity probeFlow Measurement

A pitot tube measures fluid velocity at a point from the difference between total (stagnation) and static pressure.

Pitot Tube Explained

The tip facing the flow brings fluid to rest and senses total pressure. Side holes sense static pressure. Their difference is the dynamic pressure, which gives velocity.

A single pitot measures one point, so traverses or averaging pitot tubes are used to find average velocity. They are common for air ducts, stacks and large pipes.

Pitot Tube Formula

v = √(2 Δp ÷ ρ)

v	local velocity (m/s)
Δp	dynamic pressure (Pa)
ρ	density (kg/m³)

Example: Air at 1.2 kg/m³ with 500 Pa dynamic pressure: v = √(1000 ÷ 1.2) ≈ 28.9 m/s.

Calculators for Pitot Tube

CalculatorPitot Tube CalculatorFree online calculator with formula and worked example.CalculatorPitot Traverse CalculatorFree online calculator with formula and worked example.CalculatorAveraging Pitot Tube CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is a Pitot Tube?

A pitot tube measures fluid velocity at a point from the difference between total (stagnation) and static pressure.

What is an averaging pitot tube?

A probe across the full pipe with several holes that average total pressure, giving average velocity with one DP transmitter.

Why are pitot DPs small?

Dynamic pressure is only ½ ρ v², which is low for gases at normal velocities, so sensitive low range transmitters are needed.

Learn more on the blog

Types of flow meters

A practical guide on instrumentationblog.in with more detail on pitot tube and how it is applied on real plants.

Read Full Article

More Flow Measurement Terms

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