Abstract: A mini-diluter apparatus and method are provided for preparing dilute samples of exhaust gas for emission testing. The apparatus includes first and second mass flow controllers which respectively control the mixing of exhaust gas and diluent gas samples at a constant ratio. The mixture is fed at a pressure, controlled by a back pressure regulator, to a third mass flow controller. This third controller provides a controlled sample rate (normally proportional to exhaust flow from an engine under test) to a bag sample system, or other sampling system, with excess mixture being exhausted through a pressure regulator to atmosphere. Improved accuracy and reduced calibration complexity are results of the improved apparatus and method.

Abstract: An electrode strip for use in an electrochemical sensor for measuring a compound in a sample is provided, including an electrode support, a reference or counter electrode disposed on the support, a working electrode spaced from the reference or counter electrode on the support, a covering layer defining an enclosed space over the reference and working electrodes and having an aperture for receiving a sample into the enclosed space, and a plurality of mesh layers interposed in the enclosed space between the covering layer and the support, the covering layer having a sample application aperture spaced from said electrodes and said reference electrode spaced from said working electrode at a position remote from and on the opposite side of said working electrode from said aperture.