Abstract: A gas treatment system comprises a variable flow regulator assembly placed in operable and fluid communication with a shell of a gas treatment device. The variable flow regulator assembly comprises two or more conduit portions comprising a first portion and a second portion, wherein the second portion has a coefficient of thermal expansion greater than a first coefficient of thermal expansion of the first portion. The variable flow regulator assembly structurally changes shape to alter the flow maldistribution of an exhaust gas stream into the gas treatment device when light off is achieved.

Abstract: An apparatus for sensing exhaust gas comprising: first and second tubular passages; a solid plug through which the first and second tubular passages pass and to which the tubular passages are sealingly engaged; a sampling chamber mounted to and in flow contact with the first and second tubular passages, wherein the first tubular passage provides gas flow into the sampling chamber and the second tubular passage takes gas flow out of the sampling chamber; and a flow passage having a tubular wall with an opening therein to which the solid plug is sealingly engaged, wherein the first and second tubular passages extend from inside the flow passage, through the plug, to the sampling chamber mounted outside of the flow passage.