Vasthi online monitoring stack gas analyzer (OMGA-2000 DOAS) is an one-site installation stack gas analyzer which is developed after years reaching and design on online gas analysis instruments. It can monitor gas parameters, including concentration of SO2, NOx, O2, dust, humidity, temperature, pressure, flow and etc. Vasthi online monitoring stack gas analyzer is mainly applied to tail gas emission monitoring process analysis in many fields including coal-fired power plant, waster-to-energy plant, cement factory, glass factory, lime factory, ceramics factory, sinter, coke oven, DeSOx process and DeNOx process.