IR Gas Detection

All gas molecules vibrate at a particular frequency. This vibration/rotational frequency causes the molecules to absorb light at very specific wavelengths. Targeted gas measurement can be made by measuring the absorption of infrared light at its corresponding wavelength. NDIR measures this wavelength absorption via a specific optical filter and a very sensitive infrared detector like a thermopile. The challenge is optimizing the filters, detectors, optical path, control electronics, and sampling software to ensure that measurements are accurate and stable over time.

Why Implementation of NDIR Sensors Is Important

  • Personal comfort through efficient energy consumption is the goal for HVAC systems
  • CO2, as a measured gas is the best indicator of human presence, and is an indicator of the immediate air quality – if CO2 climbs above 1,000 ppm people become drowsy leading to reduced performance
  • With CO2 sensors that can also measure dew point and temperature, you have an ideal solution to improving HVAC controls with the proven system of Demand Control Ventilation (DCV)
Average Exposure
CO<sub>2</sub> levels

Graph of CO2 profile in an office building during the course of a day with and without DCV