Infrared sensing provides real-time measurements of gases in a mixture

Infrared sensing is a flexible measurement technology based on the unique light-absorbing properties of some gases. It delivers a non-contact, real-time detection of the selected gas’s concentration in a mixture, and is widely used in our analyzer range, including portable analyzers, photometric products and multi-gas analyzers.

Our Infrared (IR) sensors focus an IR light source through a sample cell holding a continuously flowing sample of the gas mixture, and onto a detector after wavelength selection. The property of some gases to absorb unique light wavelengths can be used to detect the concentration of a selected gas in a mixture.

Depending on the intended application, this concept can be applied in two ways:

Single Beam, Single Wavelength (SBSW) delivers fast, stable and accurate real-time measurements with low maintenance requirements. It is used where a small transducer is required – the IR light source is electronically modulated, removing the need for a motor and rotating filters.

Single Beam, Dual Wavelength (SBDW) uses a pair of optical filters mounted on a rotating disc, which pass through a beam of IR light alternately. One filter (the measure filter) is chosen to pass light only at a wavelength that the gas to be measured absorbs, while the other filter (the reference filter) has a light passed through it at a wavelength unaffected by the gas to be measured. The difference in absorbance is measured by the detector and provides a direct output of the gas concentration.

Related and alternative technologies

Infrared technology is often paired with Paramagnetic sensing for dual measurements of oxygen and carbon dioxide, and works alongside Gfx sensing for many industrial applications.

Key applications

Ethylene, chlorine and TDI production

Continuous emissions monitoring

ASU process control

Key benefits

Real-time measurement response

Low maintenance requirements

Ideal for

Real-time, non-contact measurement applications, particularly where contamination might be an issue for other technologies.

Explore the Infrared analyzers we have for your process

Learn more about all our gas analyzer solutions that use this sensor technology.

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4900 Multigas


The 4900 Multigas is a high-performance CEMS analyzer designed for a wide range of multi-gas measurements.

  • Advanced digital multi-gas CEMS analysis
  • Up to four simultaneous gas stream measurements
  • Ultra-stable, accurate, non-depleting sensors
  • Auto-calibration for reduced operational needs
  • Intuitive-use icon-driven colour touchscreen
  • Digital communications for remote access

MiniHD 5200


The MiniHD 5200 portable gas analyzer is a rugged, heavy duty analyzer designed to accurately measure the levels of O2, CO and CO2 within common gas mixtures.

  • For field locations or light industrial applications
  • Measures O2, CO and CO2 in common gas mixtures
  • Portable analyser with a rugged and durable design
  • Uses digital Paramagnetic and Infrared sensing
  • Accurate measurements with no background interference
  • Intuitive, user-friendly interaction and interface

MiniMP 5200


The only truly portable battery-powered gas analyzer with MCERTS and TUV certification, offers single or dual measurement of oxygen (O2) and carbon dioxide (CO2).

  • High-performance oxygen and carbon dioxide analysis
  • Truly portable battery-powered gas analysis
  • Ideal for CEMS, with MCERTS and TUV certification
  • Accurate, long-life operation with minimal calibration
  • Combines Paramagnetic and Infrared technologies
  • Ideal for medical gas verification applications
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MultiExact 4100


A high-performance multi-gas analyzer designed to provide up to four simultaneous gas stream measurements.

SERVOPRO MultiExact 4100
  • Highly adaptable multi-gas analyzer
  • Provides up to four simultaneous measurements
  • Wide range of sensing technology options
  • Versatile solution for industrial and medical gases
  • Built-in support for moisture sensor
  • Optional advanced digital protocols

SpectraExact 2500F

SERVOTOUGH Hazardous Area

Flexible single and multicomponent gas analysis capability for corrosive, toxic and flammable sample streams.

  • Rugged, reliable photometric analysis
  • Designed for continually flammable samples
  • Suitable for hazardous area applications
  • Ideal for diverse gas sample types
  • Uses field-proven non-depleting technologies
  • Certified for gases

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Need more advice? Contact the gas analysis experts today

If you still need guidance to find the best solution for your process, we’re here to help. Our expert team combines applications knowledge with extensive experience and deep understanding of the sensing technologies available. We’ll help you find the solution that meets your unique needs.

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