A penstock or sluice gate is a type of valve for controlling water or sewerage. A Penstock valve is, in essence, a sliding door which can be operated by hand or by means of an actuator. A penstock door raises to open and allow the passage of water and lowers to isolate the flow.
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills.