Glenfield - Water Engineers to the World

SERIES 857 FREE DISCHARGE VALVE, PN16
The Series 857 Free Discharge Valve provides energy dissipation and flow control at the end or outlet from a pipework system.

Primarily they are used in bottom outlet arrangements from Dams or reservoirs, where it may be necessary to bypass a turbine, provide compensation flow to a river or rapid drawdown of the dam water level or indeed to provide desilting.

The valve is designed for operation under high flow rates and nominal bore flow rates are based on 10-15m/s.

The energy dissipation is effected by discharging a thin cylindrical curtain of water into the atmosphere where it disintegrates and loses most of its energy and falls in droplets on to the suitably sized stilling pond.

The flow enters the valve where it is split by means of the internal guide vanes and discharge is over a fixed conical shaped outlet. The flow is induced by retracting the horizontal Stainless Steel sleeve, which permits the thin high velocity cylindrical jet to be discharged.

The energy break takes place in the atmosphere thus no cavitation is experienced. The sleeve being cylindrical operates in a state of hydraulic balance hence operational forces are minimised.

The valve body barrel and cone is of one piece design and of robust cast construction, thus is much less prone to vibration than welded types.

The valves designed developed and made by us are proven in dams all over the world for more than 60 years.

Features

• Cylindrical sleeve for hydraulic balance
• External mechanism allowing easy maintenance and visible indication
• Fine screw thread for slow speed operation and fine adjustment
• Atmospheric dispersion providing excellent energy dissipation and minimum wear / erosion

BODY
Ductile Iron - BS EN 1563

SLEEVE
Stainless Steel BS EN 10088
Grade 1.4401

COATING (internally and externally)
Epoxy (250 microns) -
WRAS Approved to BS 6920

FLANGES
BS EN 1092-2, PN16