Characterization of non-dispersive infrared gas detection system for multi gas applications

Abstract

Abstract In this work, we present a low cost multi gas detection system for simultaneous measurement of up to three gases. The main conclusions are based on the investigation of the concentrations of CO2 gas as well as of CH4 gas and of H2O vapor. It was found that the continuous heating of the IR source and the absolute values of thermopile voltages are not suitable parameters for the gas detection because of their high sensitivity to the influence of temperature and/or gas flow parameters. A sine like signal is preferential for our measurement system. The amplitude of the sine is very stable and is proportional only to the concentration of particular gas (according to the optical filter) and is not dependent on the concentration of other gases or on temperature. In this way, the CO2 gas concentration can be measured from 50 ppm to 400000 ppm with the same measurement setup. The lowest detectable concentration of CH4 was about 500 ppm.