Abstract: A pneumatic conveying system for particulate material. An upper vessel includes an inlet for the material. An intermediate housing is open to and located under the inlet. A primary check valve is located in the intermediate housing and will receive the material from the inlet. A lower housing is located beneath the intermediate housing. The lower housing includes a secondary check valve therein which receives the material from the primary check valve. A material exit is located below the secondary check valve. Each of the check valves includes an opening through which the material may flow. This opening is oblique to vertical, and a movable closure member is connected to alternatively open or seal the opening. Pressurized air is supplied to the check valves in an alternating manner.