Agitators (anti-bridging devices) are usually high maintenance items that often lose parts into the product stream and damage equipment. When they fail, it is extremely difficult to discharge a bin as they cause bridging. Bins of less than 25-ton capacity are available with a 70-degree hopper bottom. Off-center hoppers (hoppered to one corner in rectangular bins or to the side in round bins) also will help to control bridging. The best mechanical anti-bridge device, either commercial or homemade, consists of rotating vertical pipe with hanging chains. Vibrating devices have not proven to be effective in preventing bridging. Complete rations have somewhat better flow characteristics than soybean meal, but they should be held in 60-degree hoppers. With regular use and proper bin and unloading conveyor design, soybean meal and other nonfree flowing materials should flow out of the bin. If occasional bridging does occur, use a rubber mallet to bump the bin hopper.
Credit: Kim Koch, North Dakota State University