Calibration · Glossary

What is a Deadweight Tester?

primary pressure standardCalibration

A deadweight tester generates a precise pressure by placing known masses on a piston of known area.

Deadweight Tester Explained

When the piston floats freely, the pressure underneath equals the weight of the masses divided by the piston area. It is a primary method for pressure.

Accurate results need corrections for local gravity, air buoyancy, temperature and the height difference to the device under test.

Deadweight Tester Formula

p = m × g_local ÷ A

m	total mass including piston (kg)
g_local	local gravity (m/s²)
A	effective piston area (m²)

Example: 10 kg on a 1 cm² piston with g = 9.80665: p ≈ 980.7 kPa, 9.807 bar.

Calculators for Deadweight Tester

CalculatorDeadweight Tester CalculatorFree online calculator with formula and worked example.CalculatorLocal Gravity CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadPressure Transmitter Calibration SOPFree step by step procedure, Word and PDF.Free downloadPressure Gauge Calibration SOP in Word and PDFFree step by step procedure, Word and PDF.

Frequently Asked Questions

What is a Deadweight Tester?

A deadweight tester generates a precise pressure by placing known masses on a piston of known area.

Why spin the weights?

Rotation reduces friction between piston and cylinder so the piston floats freely.

Why does gravity matter?

Weight depends on local g, which varies by about 0.5 % over the earth.

Learn more on the blog

Pressure gauge calibration procedure

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

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