Abstract: A pneumatically actuated hopper is provided comprising a substantially straight-walled, vertical, cylindrical main tubular body portion provided with an outwardly flared upper portion having an inverted frusto-conical configuration, a top cover having an inlet connectable with a source of vacuum, a filter screen beneath said inlet and separated therefrom by supporting means, a materials inlet beneath said filter screen leading into said hopper near the junction of said tubular body and said flared top portion, a baffle extending from said inlet within said hopper to direct materials downwardly into said tubular body, and a closure valve extending across the entire diameter of the lower discharge end of said tubular body and operable upon demand to open and expose the said entire discharge end to discharge of the material contained in said hopper.