product , such as grain , is cleansed of particulate , such as dust , as it is being conveyed in the normal receiving , storage , and shipping processes . the particulate is sucked from the product by large volumes of low velocity air . the particulate is sucked from the product at a time that the product is near a port in the side of a discharge transition of the conveyor . it is sucked at the discharge transition because at that point , the grain is in motion and agitated , as well as being near the walls of the conveyor . furthermore , the conveying of product will create a wind or movement of air which airs the sucking of the particlate from the product . the fan causing the suction is placed as near as possible to the conveyor so that the air and particulate , once removed , is moved through the particulate pipes under pressure rather than under suction . also , all of the particulate pipes carrying the particulate and air are at an angle greater than 55 ° to horizontal , the angle of repose for dust in the particulate pipes . the particulate is separated from the air in a large diameter bin which is also used to store the particulate until its removal from the particulate bin .