Butterfly valves

Butterfly valves are equipped with either a lens type or a lattice door (through-flow) type. These door types were optimized in model tests to achieve a minimum flow head loss coefficient. This type of valve is mainly used as safety valve, turbine inlet valve, and pump valve for low to medium design pressures.

They are operated by oil hydraulic systems for opening and closing, or by closing weight and hydraulic pressure for opening. For turbine inlet valves, oil pressure can also be taken from the governor hydraulic oil system. The sealing system is of flexible, adjustable rubber/metal type to reduce leakage to a minimum.

The lattice door type valves may also be equipped with a maintenance seal. The hydraulic and electric/electronic control system is part of the delivery. Auxiliary equipment such as bypass, air and vacuum valve, pipe rupture device, and connecting pipes are usually within the scope of supply. Water flow through the valve is possible in both directions.