Havy duty pumps are ideal for fluids containing large solids, shear-sensitive materials or slurries. This unique sanitary pump uses wide-opening flap check valves in place of small-clearance ball check valves, so line-size solids will pass through easily. This AODD pump features top suction and bottom discharge so gravity assists with solids passage. Ball valve pumps resist gravity and instead discharge out of the top, which allows settling solids to remain stuck inside the pump.