FREE-VALVE’s Y Type WCB body Pneumatic Flush Tank Bottom Valves(referred to as Tank valve, Y type Angle bottom valve, Bottom drain valve, Y pattern Flush bottom valve etc.) is also known as bottom valve or drain valve,Flush Bottom Valves are special purpose valves used in vessels or tanks to drain out Alumina slurry left in the vessel. These valves are most commonly used for dead space free draining or feeding of tanks.