Glenfield - Water Engineers to the World

SERIES 856 SUBMERGED DISCHARGE VALVE, PN16
The Series 856 (Fig 1600) Submerged Discharge Valve provides flow control and energy dissipation at the outlet of dams and reservoirs and in view of their design can also be used for inlet control.

In operation they discharge into a collection sump from where the water can be conducted to river, treatment works or other storage facility.

Water is supplied horizontally via an upstream pipework system and enters the valve horizontally where the valve bend turns the flow through 90 degrees vertically downwards. At the bottom of the valve the flow is agian turned through 90 degrees and is discharged horizontally and radially through specially shaped aperures into ample sized stilling sump.

The energy being released underwater enables quiet minimum vibration operation.

The key parameters relating to this arrangement ie valve and sump include an inlet velocity maximum of 6m/s and a downpipe rate of not more than 12m/s.

Sump details and water depth are also important. The sump sides are based on S =1.8 x Q1/2 where Q is in cusecs. The minimum side length should be taken as 2.5m in view of the jet exit velocity. The water depth calculation ensures cavitation free operation.

Although not always necessary it is good practice to line the sump sides with SS plate to the height of the valve openings.

Corner filets should be included in the sump design this giving a smoth free surface.

The val should be installed with its base at least 50mm above the sump floor.

Features

• Cylindrical sleeve for hydraulic balance
• Fine screw thread for slow speed operation and fine adjustment
• External mechanism allowing easy maintenance and visible indication
• Shaped multiports giving wide control range and near linear characteristic
• Stilling sump providing submerged discharge with safe, quiet energy dissipation

BODY
Ductile Iron - BS EN 1563

PORTED BODY
Gunmetal - BS EN 1982:1999 CC491K

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