Sluice gate valves are built to regulate or shut off the flow of water or other fluids by raising or lowering a sliding gate inside the valve body. This gate moves vertically and is typically operated manually, although motorized versions are also available for more complex applications. The gate itself is tightly sealed against the valve body, preventing leaks when it is closed. One ... http://mayoworld.com/sluice-gate-valves-67691