Abstract: A discharge gate assembly for sealing and controlling the flow of particulate material from a discharge opening in a hopper of the type used on semi-trailers, railroad cars or storage bins is disclosed wherein the discharge gate assembly comprises a frame which is secured over the discharge opening and has a discharge passageway through which particulate material can fall when the hopper is being emptied, a valve means in the discharge passageway to regulate the flow of material through the discharge passageway, a seal between the frame and hopper to prevent contamination from entering the discharge opening and hopper, and a cover means for sealing the lower end of the discharge passageway to prevent entry of any contaminants.