Constant volume sampling technique for pollutant concentration in exhaust gases

摘要

Method determines pollutant concentration, especially in vehicle exhaust gases . A constant volumetric flow rate of exhaust gases and cleaned air are mixed, from which mixture, a device extracts a sample. This is collected into a sample vessel during a measurement phase, before supply to an analytical unit. The air is taken from the surroundings, cleaned and stored in a pressure vessel before mixing with the exhaust gases. Also claimed is the equipment to carry out the process, in which the gases are led through a venturi section to the mixing chamber with a downstream suction unit to secure constant flow. The air (54) cleaning means (6) includes an air collection pressure vessel (50), storing it ahead of the mixing chamber (2).