This kind of valve is generally used in the hydroelectric power plants as a turbine protection to guarantee the emergency shutoff of the pressurized water flow of the penstock. It’s placed immediately before the turbine and works automatically to shut off the water flow in case of any turbine malfunction, lack of power or any specified condition.
The shutter is actuated by hydraulic cylinders moving it from the "ON" to "OFF" position by rotating of 90° on side trunnions. The valve in the open position has a fluid way which is essentially a straight cylinder so has approximately the same head losses as would occur in an equivalent length of pipe. Closure is effected by rotating the shutter 90° degrees, so it stops completely the fluid way.
To guarantee the fast closing in lack of power, suitable counterweights are installed on the shutter arm. Once shutter is closed, the perfect water tightness is guaranteed by Main Operation Seal: a downstream mobile sealing ring that closes against a fix rings seal on the shutter (both made of stainless steel with different grade of hardness). The other mobile ring is a Maintenance Seal: installed in the upstream side of the shutter, is used only in case of maintenance to the Main Operation downstream seal without the necessity to remove the valve form the site. Both of them are operated by the pressure of the water in the penstock trough a dedicated the water control system with piping. Seats NEVER touch the ball during opening or closing.
Manual system to mechanically lock/unlock the seat on the ball is available. As optional the sealing ring can be moved by pressurized oil. All construction phases, from design to testing, are carried out by Vortex Hydra in compliance with the UNI EN ISO 9001 Quality Management System.
Vortex Hydra has manufactured Spherical valves with Nominal Diameter up to 2700 mm.