Abstract
The new and reliable dilution system has been developed. This dilution system has the following characteristics. One is that flow meters installed in this system, small sonic nozzles, are traceable to the national standard. And another important characteristic is that the whole system including piping is coated using Chromium Rich Passivation surface treatment, which. shows superior characteristics for adsorption and desorption against NO, SO_2 and VOCs. The periods needed to saturate to SPAN and to ZERO were within 5 minutes for NO and SO_2 and 10-20 min for VOCs. The differences between the concentrations calculated from the flow rate ratio of the dilution system and those measured by the analyzer were 1-2 % in NO and SO_2, which is almost the same as the standard uncertainty of the concentration estimated by the dilution system, 1.3-1.8%.
