Vertical dams Vertical dams, sometimes called rising dams, are devices placed in the side of a flush tank to release the contained water. Schematic of a vertical dam flush device. Typically, vertical dams are 8 to 10 feet wide and 3 to 4 feet high. Usually, tanks associated with vertical dams are poured concrete with the frame for the vertical dam cast in place with the wall of the flush tank. Depending on the width of the gate and the depth of the tank, discharge rates with vertical dams can be as high as 10,000 gallons per minute.
Vertical dams are slightly wedge-shaped so that they seal tightly in the closed position.
Commercially available vertical dams can be configured for manual operation with a hand lever or pneumatic operation using air cylinders. A disadvantage of vertical dams is that they are usually placed at the upper end of the gutter or area being flushed. Although this placement effectively blocks any traffic in or out of the upper end of the gutter, generally, the rubber seal around the edge of the vertical dam requires periodic maintenance or replacement from repeated opening and closing. Trapdoor tanks Usually, trapdoor flush tanks for dairies are used for flushing relatively narrow alleys such as milk parlors or return alleys. These tanks are constructed of steel in a rectangular or box-like configuration.