GZAUsage of these controlled tight and check butterfly valves provides high reliability. They are mainly used for power station cooling systems and penstock systems of hydroelectric power plants. The GZA may be used as a pipe break safety device, as a turbine inlet emergency shut-down valve for turbine protection, or as a check valve for pump protection.
Operation is via closing weight and hydraulic servo-actuator. This fool proof system is reliable in critical situations – even in complete power failure. The servo-actuator opens the valve disk and acts as a powerful hydraulic damper during closing. To prevent water hammer within the penstock system, adjustable multi-stage damping units can be supplied.
Nominal Diameters: DN 500-4000
Temperature range: from minus 20°С to plus 150°С
Pressure stages: PN 2,5/6/10/16/25/40/64; ANSI 150/300


  •  Controlled emergency shut-down valve with tight shut-off and check valve function;
  •  Hydrodynamically profiled disc;
  •  Double eccentric shaft;
  •  Operation: externally located closing weight and hydraulic servo-actuator.



  •  Low flow loss coefficients;
  •  Maintenance friendly design; 
  •  Tailored design with extensive accessories.



  •  Back-up seal for maintenance;
  •  Multi-rate adjustable interval damping system;
  •  Hydraulic operation;
  •  Electric control systems;
  •  Overspeed detector;
  •  Orifice plates;
  •  Disk locking device;
  •  Vulcanized hard rubber coating;
  •  Butt weld ends.