Dredge valve

The dredge valve is a component of a Cutter Suction Dredge or a Trailing Suction Hopper Dredger that is used control the flow of water and sand in the suction and discharge pipes of one of these types of dredgers.
There are 3 cases when this vertical valve can block or reduce the mixture flow of water and sand by lowering its gate: 
The dredge valve’s gate is hydraulically control and it has raised a lot of challenges because of maintaining it clean. The gate can be blocked by the sand that enter thorough the dredge valve causing a lot of damages. Because of this reason the dredge valve has a lot of water flushing canals in order to keep it clean.
See also.
Gate valve