What Is The Infrared (NDIR) CO2 Sensors And Its Application

What is the Nondispersive infrared (NDIR) CO2 sensors

  NDIR sensors are spectroscopic sensors to detect CO2 in a gaseous environment by its characteristic absorption. The key components are an infrared source, a light tube, an interference (wavelength) filter, and an infrared detector. The gas is pumped or diffuses into the light tube, and the electronics measure the absorption of the characteristic wavelength of light. NDIR sensors are most often used for measuring carbon dioxide. The best of these have sensitivities of 20–50 PPM. Typical NDIR sensors cost in the (US) $100 to $1000 range.

  NDIR CO2 sensors are also used for dissolved CO2 for applications such as beverage carbonation, pharmaceutical fermentation and CO2 sequestration applications. In this case they are mated to an ATR (attenuated total reflection) optic and measure the gas in situ. New developments include using microelectromechanical systems (MEMS) IR sources to bring down the costs of this sensor and to create smaller devices (for example for use in air conditioning applications).

Applications

• Modified atmospheres
• Indoor air quality
• Stowaway detection
• Cellar and gas stores
• Marine vessels
• Greenhouses
• Landfill gas
• Confined spaces
• Aerospace
• Healthcare
• Horticulture
• Transportation
• Cryogenics
• Ventilation management
• Mining
• Rebreathers (SCUBA)
• Decaffeination
• For indoor human occupancy counting
• For HVAC applications, CO2 sensors can be used to monitor the quality of air and the tailored need for fresh air, respectively. Measuring CO2 levels indirectly determines how many people are in a room, and ventilation can be adjusted accordingly.