Gate Valve [1]

A valve used to restrict or stop the flow of liquids through a pipe in applications where petroleum [2] products are moved in bulk quantities; at a bulk plant [3] or terminal [4].

A gate valve, in a sense, performs like a gate inside a pipe, allowing product to flow when it is open, stopping the flow when it is closed. 

The blockage is provided by a flat plate that is moved into the closed position by operation of the handle. Gate valves may be operated either manually or through use of power controls.