Pressure Measurement · Glossary

What is a Bourdon Tube?

mechanical pressure elementPressure Measurement

A Bourdon tube is a curved tube of oval cross section that straightens as pressure rises, moving the gauge pointer.

Bourdon Tube Explained

Pressure inside the flattened tube tries to make it round, which unwinds the curve. A link and gear movement turns this small motion into pointer rotation.

C shape tubes suit most ranges; spiral and helical tubes give more movement for low pressures and recorders. Bourdon gauges are simple, but sensitive to pulsation and overpressure.

Bourdon Tube: Typical Values

Recommended working range (EN 837-2)	up to ¾ of full scale steady, ⅔ fluctuating
Common accuracy classes	1.0, 1.6, 2.5 (% of span)

Calculators for Bourdon Tube

CalculatorPressure Gauge Range SelectorFree online calculator with formula and worked example.CalculatorPressure Gauge Accuracy CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadPressure Gauge Datasheet Template in Excel with Range CheckFree download in Excel and PDF.Free downloadPressure Gauge Calibration SOP in Word and PDFFree step by step procedure, Word and PDF.

Frequently Asked Questions

What is a Bourdon Tube?

A Bourdon tube is a curved tube of oval cross section that straightens as pressure rises, moving the gauge pointer.

Why fill a gauge with glycerine?

The liquid damps pointer movement from vibration and pulsation and lubricates the movement.

Can a Bourdon gauge measure vacuum?

Yes. Compound and vacuum gauges use the tube curling inwards below atmospheric pressure.

Learn more on the blog

Pressure gauge calibration procedure

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

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More Pressure Measurement Terms

Pressure termFill FluidFill fluid is the incompressible liquid inside a pressure sensor or diaphragm seal that transmits…Pressure termZero Elevation and SuppressionZero elevation and suppression shift a transmitter range to cancel the head of liquid in impulse lines or…Pressure termPiezoresistive Pressure SensorA piezoresistive pressure sensor uses resistors on a diaphragm whose resistance changes with strain as…Pressure termCapacitive Pressure SensorA capacitive pressure sensor measures pressure from the change in capacitance as a diaphragm moves…Pressure termStatic Pressure EffectStatic pressure effect is the change in a DP transmitter reading caused by line pressure acting on both sides.Pressure termManometerA manometer measures pressure from the height difference of a liquid column in a U tube or inclined tube.

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