The portable standard gas dilutor instrument has the characteristics of large dilution ratio, high flow control, simple operation, light and portable, etc., which fully meets the requirements of on-site calibration of flue gas analyzer for ultra-low emission monitoring of air pollution sources, and conforms to the national standard HJ57-2017 determination of sulfur dioxide in exhaust gas from stationary pollution sources .The requirements of CO interference test for dilution gas distribution device in "constant potential electrolysis method" and meet the requirements of field and laboratory standard gas configuration.