What is a Flow Control?
How does a stormwater tank prevent downstream flooding during periods of heavy rainfall? It’s all down to a flow control device that manages the release of water to ensure drainage happens at a rate that protects the local environment. We explain more about flow controls below.
What is a flow control?
A flow control device plays an important role managing the rate of water drainage from a storm water attenuation tank. If an existing system does not feature a flow control chamber some can be retro-fitted to accommodate one. The chamber features a combination of flow controls that will help lower the risk of erosion, flooding and environment damage. Flow controls can be purchased as part of a full system, within a chamber, or as individual units. Their ability to manage stormwater drainage is essential to the success of sustainable drainage systems (SuDS).
What are sustainable drainage systems (SuDS)?
Storm attenuation tanks are classed as SuDs, as they are designed to prevent a build-up of large amounts of surface water from creating a flood. This is done by slowing down the rate of water that is able to enter the drainage network.
SuDs are becoming ever more important to residents right across the UK as flooding is more of an issue due to environmental changes. Increasingly they are also becoming a preferred option for local authorities who are wary of overloading existing drainage systems that may be working at capacity.
How does flow control work?
Flow control is a self-activating device that is able to deliver better hydraulic performance than you’d experience with conventional flow controls like throttle pipes, orifice plates and reduced maintenance requirements.
A flow control system features an intake, a volute and an outlet. Flow is directed into the volute where a vortex is formed. An air-filled core is created by high peripheral velocities, inducing back pressure that is then able to reduce the discharge rate of the flow.
What are the advantages of a flow control?
Some of the most notable advantages of flow control include:
- As mentioned above, flow control offers better hydraulic performances than conventional flow controls like throttle pipes and orifice pipes. This is due to the larger pipe opening, which also lowers the risk of blockages occurring.
- Flow controls are also versatile, with GRAF’s Vortex flow control system ready for use with underground tanks, retention tanks provided by the customer and storage modules, wielded into watertight liners
- Minimal maintenance is required with a flow control due to the self-cleaning effect created by the vortex flow, and once the system is installed it can be left to operate as and when needed. There are a range of different sizes available to suit specific requirements.
What flow control devices are available?
GRAF’s Vortex flow control shaft is able to manage volume flows of up to 65 l/s. To ensure the best results it is recommended for use with either retention systems fitted with Graf EcoBloc ditch elements or retention cisterns.
Three size options are available:
- Large: 820mm (L) x 700mm (W) x 1935mm (H)
- Medium: 795mm (L) x 700mm (W) x 1880mm (H)
- Small 615mm (L) x 475mm (W) x 1135mm (H).