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IBS - Flap Valves
A Flap valve is a type of non-return valve that prevents liquid from returning back up a discharge pipe or a culvert. A flow of liquid arriving from the upstream end of the system, will hit the back face of the flap valve door and push it off its’ seating face away from the frame – this allows the flow of liquid to continue. Once the flow of liquid has ceased, the door will swing back and rest against the sealing face on the frame, once again closing the orifice. Any liquid building up against the front face of the door or flap will serve to push the door or flap further against the sealing face on the frame ensuring a water tight seal – at this point no liquid can flow back through the orifice, thus preventing “back-flow”.
Flap valves can be used in many applications and locations, including:
- Flood Control
- Sewer flooding prevention
- Back-flow prevention
- Culvert Isolation
- River Outfalls
- Tidal Outfalls
Flap valves are typically circular, square or rectangular in shape dependent upon the application and consist of a frame (fixed to a surface or pipe flange), a door (or flap) and a hinge and pin arrangement from which the door (or flap) hangs.
Flap valves come in all shapes and sizes and can be made bespoke to specific project requirements, including but not limited to:
- Fish/Eel Friendly applications
- Pumped flow or gravity flow
- Reinforced doors/flaps for larger scale openings
- Reveal fix applications for when surface mounting is not feasible
- Winching arrangements can be added to allow for manually opening the flap valves for ongoing maintenance purposes
Flap valves from IBS are available in the following materials :
- HDPE
- HMPE
- Stainless steel 304 or 316L
- Duplex or super duplex
Generally, flap valves are fixed to concrete headwalls and sit over the outfall orifice, but they can also be installed on the end of an outfall pipe via a flanged connection or alternatively with the reveal of an opening itself if required.
Flap valves normally protect sewage and surface water outfalls from back-flow due to flood and/or tidal applications. Flap valves can also offer odour protection by ensuring the outfalls are always closed when not in use.