Abstract: A stationary or portable conveying system for conveying particulate dry products is disclosed. The conveying apparatus is 100% air operated, with few moving parts, and requires no electric controls, no rotary valves and no timers. The apparatus disclosed includes a storage vessel provided with product intake and discharge openings. The valving associated with the storage vessel automatically operates alternately to admit product to the storage vessel during an intake cycle and, when the storage vessel is full, to automatically shift to a discharge cycle to unload the product from the storage vessel. A valve mounted to the vessel near the top detects the level of product in the vessel. The valve includes a generally cylindrical body having a central bore communicating with a plurality of ports. A longitudinally displaceable valve stem is mounted in the bore and is spring biased to project beyond one end of the valve body.