| CPC G01N 1/2205 (2013.01) [G01N 1/2252 (2013.01); G01N 1/38 (2013.01); G01N 15/0618 (2013.01); G01N 2001/2255 (2013.01)] | 12 Claims | 

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               1. A sampling system of particulate matter for vehicle emission tests, the system comprising: 
            a probe configured to sample vehicle emissions carrying particulate matter, the probe directing the sampled particulate matter into a channel of a plurality of channels; 
                a filter holder positioned within at least one of the plurality of channels, wherein at least one of the plurality of channels does not include a filter holder; 
                valves arranged and configured to direct the vehicle emissions into a specified channel of the plurality of channels; 
                a sampling pump configured to flow the vehicle emissions through at least one channel of the plurality of channels; and 
                a mass flow meter arranged to receive the vehicle emissions from the plurality of channels; 
                a balloon configured to reduce pulsations in the mass flow meter caused by the sampling pump; 
                a cylinder configured to reduce pulsations in the mass flow meter caused by the sampling pump; and 
                a return arranged to direct the flow to a constant volume sampler. 
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