What Is NDIR Technology, and How Does it Work in CO2 Monitors?

Author: Scott Jones
Marketing Content Writer
Date of publication: 11.03.22 Updated: 26.07.23

Carbon dioxide (CO2) Sensor Technology Explained.

NDIR (nondispersive infrared) is a gas concentration measurement method that uses the unique absorption wavelength range of selected gases to determine the presence of a target gas, in this case, CO2. 

The process is relatively simple. Infrared light (or an LED) is sent from one end of a test chamber towards the other end. As the amount of CO2 entering the chamber increases, the amount of Infrared light travelling through the chamber decreases. The sensor measures this decrease in intensity. The higher the intensity of CO2, the higher the CO2 content in the environment. 

The original NDIR technology was pioneered following World War II. The original components were quite large and cumbersome. Today’s solid state monitors utilizing the NDIR process are significantly lighter and more stable. Previous generations of the monitors were more sensitive to vibration and contamination. 

Today’s dual wavelength NDIR units typically have a single detector with reference and gas optical filters . One is used as a reference, to provide stability and reference, while the gas filter provides the actual measurement. 

NDIR sensors have no actual contact with gas. This makes these monitors much more reliable, as they can be tailored to specific gases without the potential for being affected by other gases.

While many gas monitors and detector systems utilize electrochemical technology, NDIR monitors do not actually interact with the target gases – electrochemical units have the potential to interact with multiple gases, reducing their effectiveness. 

The NDIR technology is so accurate, cost-effective and versatile, engineers with the Analox Group use Non-Dispersive Infrared sensing technology in ALL of the company’s extensive range of CO2 monitoring equipment.

Analox has also incorporated Gas Filter Correlation (GFC), a specialized form of GFC/GFX that has been developed to allow highly specialized and select gas properties to be incorporated into the analyzer. In short, the monitor is “programmed” with the specific properties of CO2 and can monitor exclusively for that gas. This helps filter out unwanted gases and provide an even more safe and accurate measurement. 

Analox developers include GFC technology in the company’s widely-respected VENUS product line, and in unique OEM projects where precision and customization are necessary. 

For more details on the entire Analox line of CO2 gas monitoring solutions, contact your local Analox dealer.