UV DOAS Ultraviolet differential optical absorption gas analyzer is an independently self-developed flue gas analyzer product that is suitable for online gas analysis of environmental protection and industrial controlling purposes. Based on the Ultraviolet absorption spectrum and differential optical absorption spectrum principle, it adopts the unique optical technology platform, where it carries out the online analyzer and measurement for the concentration of gases such as SO2, NO, O2, H2S, Cl2, NH3, NO2, CO, and CO2, etc. Under normal conditions, the gas component of SO2, NO, and O2, is measured and other gas components can be extended. one analyzer can simultaneously carry out the measurement for 5 gas components at a maximum.