Figure 11Partial flow dilution system with flow control and total sampling
Raw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the sampling probe SP and the transfer tube TT. The total flow through the tunnel is adjusted with the flow controller FC3 and the sampling pump P of the particulate sampling system (see Figure 16). The dilution air flow is controlled by the flow controller FC2, which may use GEXH, GAIR or GFUELas command signals, for the desired exhaust split. The sample flow into DT is the difference of the total flow dilution air flow. The dilution air flow rate is measured with flow measurement device FM1, the total flow rate with the flow measurement device FM3 of the particulate sampling system (see Figure 14). The dilution ratio is calculated from these two flow rates.