Analytical · Glossary

What is an NDIR Gas Analyser?

infrared absorptionAnalytical

An NDIR gas analyser measures gases such as CO₂, CO and methane from how much infrared light they absorb at specific wavelengths.

NDIR Gas Analyser Explained

Non dispersive infrared analysers pass broadband IR through the sample and use filters for the target gas wavelength. Absorption follows the Beer Lambert law.

Water vapour and other gases can interfere, so sample drying and filter selection matter.

NDIR Gas Analyser Formula

I = I₀ × e^{−ε c L}

I₀, I	incident and transmitted intensity
c	gas concentration
L	path length
ε	absorption coefficient

Calculators for NDIR Gas Analyser

Calculatorppm to mg/m3 CalculatorFree online calculator with formula and worked example.CalculatorSpan Gas Dilution CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadGas Detector Datasheet Template in ExcelFree download in Excel and PDF.

Frequently Asked Questions

What is an NDIR Gas Analyser?

An NDIR gas analyser measures gases such as CO₂, CO and methane from how much infrared light they absorb at specific wavelengths.

Can NDIR measure oxygen?

No, oxygen does not absorb IR; paramagnetic or zirconia analysers are used.

Why do IR gas detectors not poison?

The measurement is optical, so contaminants that poison catalytic beads do not affect it.

Learn more on the blog

Instrumentation and control standards

A practical guide on instrumentationblog.in with more detail on NDIR gas analyser and how it is applied on real plants.

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