Abstract: A sample chamber for a gas analyzer for use in a duct containing gases to be analyzed is disclosed and includes a flow directing apparatus formed by a pair of spaced members which form a passage therebetween in the form of a converging diverging throat and an outer housing at least partially surrounding the flow directing apparatus. This outer housing has at least a pair of apertures and is movable by a suitable apparatus between one position in which the outer housing apertures are generally aligned with the flow directing passage and another position in which the outer housing apertures are spaced from the passage with non-apertured portions of the outer housing positioned across the ends of that passage.

Abstract: By providing an input/output panel housing which is readily connectible to adjacent housings and which cooperates with up to four removable input/output modules, a completely expandable, modularized input/output panel construction is achieved. Each housing accommodates up to four "plug-in" input/output modules, and is constructed so that the wiring from the equipment being controlled is connected directly to fixed terminals and need not be removed when the input/output modules are removed or replaced. Since each housing is readily connectible to adjacent housings, the input/output panel board construction of this invention is completely flexible and readily expandable to meet any desired operational needs.