GENERATION AND EVALUATION OF TEST GAS-MIXTURES FOR THE GAS-PHASE SULFUR INTERCOMPARISON EXPERIMENT

The automated sulfur gas dilution system (ASGDS) was used during the G as-Phase Sulfur Intercomparison Experiment (GASIE) to generate and ana lyze test gas mixtures containing pptv levels of SO2 in the presence o f various suites of potential measurement interferent gases. These tes t gas mixtures were provided in a 100 standard liters per minute air m atrix manifold, allowing simultaneous sampling by all seven intercompa rison participants. The test gas mixtures were homogeneous within the 90-min test periods of the synthetic air phases of GASIE, allowing rig orous intercomparison of any two or more data points obtained during a given test period. A number of delivered SO2 concentrations were succ essfully replicated throughout the experiment, permitting the collecti on of a sufficient amount of data for statistical evaluation, The SO2 concentrations measured by the ASGDS quality control instrumentation a greed with values obtained by the intercomparison participants but wer e different from the set point values.