Abstract: There is provided a fluid sample bag for use in testing automotive exhaust samples and the like. The bag can be sealed and formed of a material which is flexible and impermeable to gases. A fitting is sealingly connected to the bag for filling and evacuating the bag. A spacing element is carried on the fitting and disposed in the interior of the bag, extending substantially throughout the interior of the bag and closely adjacent the perimeter of the bag when the bag is collapsed. The spacing element is a sheet of mesh material or other grid-like array that forms a plurality of passages which provide for fluid flow between the fitting and substantially everywhere within the bag when the bag collapses on the spacing element. The spacing element is polyester, stainless steel or the like, depending on the sample application, so as to be inert with the sample.