Abstract: A limp, porous membrane of sheet (i.e., cloth) material for a fluidized outlet is disclosed. The outlet is in communication with a container, such as a hopper within a covered hopper railway car, containing a supply of particulate material for being fluidized and unloaded via the outlet. The outlet comprises an outlet housing, an outlet frame for securing the outlet housing to the hopper, an outlet opening, and outlet walls extending from the frame to the outlet opening. The membrane is secured to the outlet frame and to the outlet opening and is disposed generally on the inside faces of the outlet walls. A manifold is provided for introducing a fluidizing fluid (e.g., air) under pressure between the outlet walls and the membrane such that the fluidizing fluid flows through the membrane thereby to fluidize the lading above the membrane.