NDIR gas sensors respond very well to most small molecule gases and are highly selective. With a suitable narrow band optical filter, it is possible to measure only the gas of interest. In contrast, other technologies like electrochemical sensors can have high cross sensitivity and might react also to other gases. Therefore, applying NDIR detection can result in high accuracy cost effective measurements.
For leak detection, small concentrations may be of interest and gas detection limits have to be taken into consideration. Due to the fact that thermopiles do not provide the highest detectivity, their detection limits are higher than some other technologies, but they provide the advantage of very affordable prices. The detection limit for a thermopile NDIR CO2 sensor is in the range of 9 ppm, while other technologies can achieve 4 ppm or less.