Abstract: A fluid flow control device includes a first fluid flow passageway, a fluid inlet into the first passageway, a fluid outlet from the first passageway, a second fluid flow passageway in flow communication with the first passageway, and a fluid flow-through opening in fluid flow communication with the second passageway. The fluid flow control device is controlled to selectively provide, alternatively, a vacuum or a pressure condition at the flow-through opening. A pneumatic transfer system is also disclosed for alternately transferring a batch of particulate material from a storage area to a batching vessel, and for transferring the particulate material from the batching vessel to a remote location. The system includes a single blower having its high pressure side in flow communication with the fluid flow control device for selectively providing both vacuum and pressure conditions in the batching vessel to effect the selected transferring of particulate material into and out of the batching vessel.