Penstocks (sluice gates) isolate channel flow via a vertical sliding gate in square, rectangular or round openings from 150×150 mm to DN3000. Cast iron (GG25/GGG40) or stainless steel (SS304/316L) frames with EPDM/NBR/Neoprene or metal seats give bi-directional zero-leakage sealing under head pressure. Wall-mounted, low-friction guide rails, manual handwheel, electric, pneumatic or hydraulic actuation. For water, wastewater, flood control, irrigation, power cooling inlets per AWWA/DIN/BS.