Float-controlled Flap Valves
The illustration above details a Float Controlled Flap Valve which is specifically designed for level control as opposed to the control of discharge rates.
The Float Controlled Flap Valve is of particular benefit in preventing "surcharging” in pump storage wells or, for Archimedean Screw Pumps, controlling inflow from subsidiary sources so that the liquid level at the inlet to the screw pumps may be at the height most suitable for maximum efficiency of the pumps. They are also of benefit in Flood
Relief projects, allowing floodwater to be retained behind flood banks or similar structures whereby the valves automatically permit the floodwater to return to the water course as the down stream level falls. This often precludes the necessity of providing electric power to control electric penstocks or the manpower necessary to operate the penstocks manually.