Valve

A device used to control the flow in a conduit, pipe, or tunnel that permanently obstructs a portion of the waterway. As distinguished from gates, valves are constructed so that the closing member remains in the water passageway for all operating positions. See butterfly valve, fixed cone valve (Howell Bunger valve), Ensign valve, gate valve, hollow-jet valve, needle valve, and tube valve.

A device fitted to a pipeline or orifice in which the closure member is either rotated or moved transversely or longitudinally in the waterway to control or stop flow.

A device fitted to a pipeline or orifice in which the closure member is either rotated or moved in some way as to control or stop flow.

In hydrologic terms, a device fitted to a pipeline or orifice in which the closure member is either rotated or moved in some way as to control or stop flow.