The Rotary Feeder / Rotary valve / airlock introduces material into the conveying system at highest volumetric efficiency when material flow into the feeder is controlled to permit free venting. The feeder may be used under a head of material when appropriate aeration is provided to create a path for relief of the reverse air flow. In operation, air enters a single inlet and passes into the rotor pocket through two (2) ducts integrally cast in the end plates, assuring complete fluidization and discharge. High efficiency is attained through the combination of gravity and air-sweeping of the fluidized material into the conveying line. This design principle assists greatly in discharging materials which have a tendency of hanging up in the rotor pockets. The rotary feeder permits the use of smaller sized components and related equipment in pressure pneumatic conveying systems resulting in savings in initial equipment cost, installation cost and space requirements.