Particulate sampler and dilution gas flow device arrangement for an exhaust sampling system

Abstract

An exhaust sampling system is provided that includes a sampler having a sample inlet for receiving an exhaust gas sample. The sampler includes a mixer for receiving the exhaust gas sample and a diluent to produce a diluted exhaust gas. The exhaust sampling system includes first and second dilution gas flow devices. The first and second dilution gas flow devices are fluidly connected to one another at a second junction. Any diluent provided by the first and second dilution gas flow devices intermingles with one another prior to reaching the mixer. A diluted sample flow meter is arranged downstream from the mixer for receiving the diluted exhaust gas. In one example, diluent flow from the first and second dilution gas flow devices intermingles before being introduced to the mixer. In another example, diluent flow from the first dilution gas flow device is leaked out of the second dilution gas flow device in a controlled manner to achieve a desired diluent flow into the mixer. The example exhaust sampling system does not require a measurement of the flow of exhaust gas sample into the system. Instead, the flow of the diluted exhaust gas is measured by the diluted sample flow meter. And, the flow of diluent through the first and second dilution flow meters is measured and the net flow through the first and second dilution flow meters is subtracted from the flow of the diluted exhaust gas through the diluted sample flow meter.