Evaluation of an UV-Analyzer for the Simultaneous NO and NO2 Vehicle Emission Measurement

For the measurement of NO and NO₂ the CLD-analyzer (chemiluminescense detector) has been used for more than twenty-five years. The disadvantage of the CLD is that NO can be measured only. To obtain total NO_X (NO+NO₂) the exhaust gas sample has to flow through a catalytic converter, which reduces NO₂ to NO. The converter has a efficiency between 90 and 100%. For precise NO and NO₂ values it is an advantage to analyze NO and NO₂ directly. This paper describes a new UV NO_X-analyzer for the simultaneous measurement of NO and NO₂. Two different configurations, for high and low concentrations, eg. CVS-bag analysis are presented. The performance of the analyzers is documented in comparison to the UV-RAS analyzer with converter for NO_X [1] and the conventional CLD-analyzer. The benefits of the new analyzer compared to analyzers equipped with a converter are given in detailed test results.