Design and engineering services
in hydromechanics and hydroelectric
Flap gate
Dam gate designed for upstream level control by overflow.
Flap gates are designed for use in open-channel flows where upstream level control is required. The design includes a bottom hinge and a channel-floor recess that enables the fully opened gate to lie flat on the channel floor.
The premise of the design is that of a moveable weir. Flap gates are operated by hydraulic cylinder, chain or cable hoists.
These gates consist of a gate leaf closing a sluice. The gate leaf rotates partially around a bottom hinge operated by a hoist mechanism. The action of this gate can be likened to a drawbridge hinged across the bottom of a vertical walled channel.
When the gate position is horizontal (fully open), water flows through the channel end of the gate. Water flows over the crest while the channel sides restrict it. Water backs up behind the gate as it rises, and water excess flows over the crest of the gate leaf. The flap gate can be set to any position between 0° and 60° (0° being horizontal or open), therefore acting as upstream water level or water flow control.
Applications:
The gate makes it possible to finely control the upstream water level. When it is equipped with position encoders, it can also control and regulate the values of forwarded flows.
Safety:
Due to its design, the flap gate has a natural tendency to the opening under the action of the water pressure. This characteristic makes of it a perfect safety device, able to let pass the flow even in the lack of external energy. Moreover, its capacity to leave debris of the river pass over and carry on downstream makes it highly reliable.
Type of handling mechanism:
The gate can be operated by one or more hydraulic cylinders, by an electric actuator, directly or via cables or chains. Many alternatives of positioning of the hoist mechanism make it possible to adapt to all the sites.