An exhaust flow tube system for use with emissions test equipment and associated parts and systems

A network of tubes or conduits for use in an exhaust flow tube system comprises emissions test equipment 4 including a first probe 41a and a second probe 41b. A primary flow tube 21 receives exhaust gases from an engine exhaust pipe 3 and delivers the gases to the first probe. A secondary flow tube 22 delivers exhaust gases from the engine to the second probe. A valve 11, which may be a butterfly valve, controls the flow of gases through the secondary flow tube and is actuated between a first configuration in which the flow of gas through the secondary flow tube is prevented, and a second configuration in which the flow of gas is permitted. The probes may extend into the flow of gas through the tubes and measure the flow rate of gas. The probes may include a pitot tube and associated transducer module or an ultrasonic exhaust flow meter. An emissions measurement system and a test facility may include the network of tubes or conduits.