Sulfur Dioxide analyzing instrument is based on the principle of absorbing ultra-violet. Ultra-violet would absorb ultra-violet with wavelength of 220 to 240 nm. After SO2 particles absorb ultra-violet, fluorescence with wavelength of 300 to 400 nm will be produced, and the total amount of produced fluorescence is directly proportional to the amount of SO2. Therefore, we can use this attribute to analyze the concentration of SO2 in the air.
The sample gas within of the atmosphere is sampled using a vacuum pump and input into the system. The sample gas usually includes hydrocarbon, which would interfere with the concentration analysis of SO2. The hydrocarbon must be removed from the sample through removal equipment, and then the sample gas can be sent into the reaction cell for analysis. Ultra-violet will go through a lens plated with zinc, which can separate out the ultra-violet with wavelength of 214 nm and gather it in the reaction cell to react with SO2. The fluorescence produced after the reaction will be gathered at the photoelectric multiplier and eventually transferred into electronic signals. The processing system can then compute the concentration of SO2 within the air.