The principle of non-dispersive infrared gas sensing technology is that the gas absorption of characteristic infrared wavelengths conforms to Lambert-Beer's law. The basic principle is that an infrared light source emits an infrared beam through the sampling gas chamber, and each gas component in the sample gas absorbs a specific frequency infrared rays. By the detector to receive and measure the infrared absorption of the corresponding frequency, combined with the algorithm analysis set in the embedded software, the concentration of the gas component can be measured. The reason why this technique is non-dispersive is that the wavelength passing through the sampling gas cell is not pre-filtered.
Different gases have their own different absorption spectra due to differences in their molecular structure, concentration and energy distribution. If the absorption peaks of different gases overlap, the mutual interference between these gases must be dealt with. In addition, in a specific wavelength range, gas detection will also be interfered by moisture. Therefore, the use of non-dispersive infrared technology for gas measurement needs to solve the problems of cross interference between different gases, high and low temperature effects, humidity effects, and component noise effects. This requires the integration of gas path, circuit, optical path design and software algorithm Cooperate.
Compared with electrochemistry,catalytic combustion, solid electrolyte, semiconductor, and photo acoustic methods, the NDIR detection method has the following advantages:Good selectivity, not susceptible to poisoning and aging due to harmful gases, fast response speed and good stability, low cost, high signal-to-noise ratio, etc.