Grain Flow Through Guarded Horizontal Orifices

Installing guards over unloading sumps in grain bins would reduce injuries caused by accidental contact with screw conveyors used to unload bins. But installing guards would also reduce the rate of grain flow from the bins. This study was undertaken to measure flow of wheat, corn, sorghum, and soybeans through guarded and unguarded 15 cm (6 in.) and 23 cm (9 in.) square, horizontal orifices, and to determine the flow reduction caused by the guards. The ratio of guarded to unguarded volumetric grain flow ranged from 0.34 to 0.69 depending on grain type and orifice size. We tried to predict grain flow through guarded orifices by summing theoretical grain flow through the small openings in the guards. The ratios of measured to predicted grain flow for guarded orifices were 1.07 to 1.32 for wheat, 0.94 to 1.17 for corn, 0.85 to 0.91 for sorghum, and 0.73 to 0.87 for soybeans.