Fast sampling devices for dynamic exhaust gas analysis

We report on a fast exhaust gas sampling system, optimized for infrared diode laser gas analysis, but also applicable to other techniques. A system response time of 3 ms and a gas delay time of appr. 20 ms were determined by fast spectroscopic analysis of injected test gas pulses and confirmed by dynamic test bed experiments for NO. Deviations of sample gas temperature and pressure (transient and static) at the optical measurement location behind the sampling line amount to smaller than 5 % from the nominal values of 470 K (190 xC) and 50 mbar. We also describe a low-cost infrared sensor with pulsed carbon dioxide gas injection for the determination of the temporal gas transfer behaviour of fast gas sampling systems.