US Patent 7281440 Particulate sampling system having flow check device

A particulate sampling system is disclosed. The particulate sampling system may include an exhaust sampling unit and a dilution flow assembly to supply dilution air to the exhaust sampling unit. The particulate sampling system may also include a total flow assembly to receive dilution air and exhaust. The particulate sampling system may further include a flow regulation assembly configured to control flow rates in the dilution flow assembly and the total flow assembly. The particulate sampling system may also include a flow check assembly configured to measure the accuracy of the flow regulation assembly.