Abstract: A sample of gaseous constituents, to be used in e.g. emissions testing, is collected within an inner bag 86 having a wall 92 that allows limited diffusion of at least one of the gaseous constituents therethrough. A control gas is then collected into an outer bag 82 that defines an auxiliary chamber 94 between the wall and the outside environment. The control gas controls the rate of diffusion of the at least one constituent through the wall and into the outside environment.

Abstract: A sample bag for collecting a sample of gaseous constituents defines a sample chamber with a wall that allows a constituent to diffuse therethrough, and defines an auxiliary chamber on the other side of the wall to receive the diffusing constituent. Advantageously, a control gas may be provided in the auxiliary chamber to control the rate of net diffusion across the wall of the sample chamber. The control gas may be the same as the sample gas.

Abstract: An apparatus adapted for analyzing exhaust emissions by using a small fraction of a continuously-extracted exhaust sample combined with a pollutant-free diluent through a system of critical flow orifices at a predetermined and precisely controlled flow ratio. A small quantity of gas is extracted from the diluted exhaust gas available which is diluted with the contaminant-free air or nitrogen to produce a mixture having a dew point below ambient air temperature and satisfying the flow requirements of the analysis system. The diluted sample may then be analyzed to obtain the total mass of pollutants through identification of the instantaneous exhaust concentration rate and the exhaust mass flow rate or through identification of the concentration of pollutants collected in a sample bag and the total exhaust volume.

Abstract: A gas dividing and blending system including a gas divider for generating a mid-span gas for more than one analyzer at the same time so that the analyzers can run their mid-span checks at the same time. A mid-span gas is generated using the span gases for the analyzers. If desired, a separate diluent gas may also be mixed with the span gases to generate a mid-span gas. Once a mid-span gas is generated, it is then simultaneously delivered to each analyzer which uses the mid-span gas to perform its mid-span gas check at the same time as the other analyzers.

Abstract: An apparatus and method are adapted for analyzing exhaust emissions by using a small fraction of a continuously-extracted exhaust sample combined with a pollutant-free diluent through a system of critical flow orifices at a predetermined and precisely controlled flow ratio. A small quantity of gas is extracted from the diluted exhaust gas available which is diluted with the contaminant-free air or nitrogen to produce a mixture having a dew point below ambient air temperature and satisfying the flow requirements of the analysis system.

Abstract: The present invention is directed to certain modifications to sensor cells to minimize electrolyte dilution or loss and to reduce electrical noise. These objectives are attained by designing and constructing the cell in such a manner as to force the electrolyte to communicate between the anode and cathode by diffusion through a porous plug which is placed adjacent the cathode and in contact with the required porous membrane.

Abstract: The present invention is directed to a means for compensating for pressure changes in sensing devices. To assure accurate measurements with sensing devices immersed in a medium, it is necessary to have external and internal pressures preferably the same or very close. This invention provides pressure compensation through the use of at least one but preferably a plurality of passages communicating the exterior to the interior of the cell. The passage preferably but not necessarily is so designed as to provide an inner portion of the passage with a greater dimension than the remainder. In the greater dimensioned portion of the passage is positioned a substantially non-tensioned membrane so as to provide a separation or barrier between the interior and exterior of the cell.