Energy-free flow control for FAS –
space-saving control for large impounding heads

The Challenge

Our weath­er pat­terns are chang­ing with localised extreme rain events becom­ing more com­mon and gen­er­at­ing large water vol­umes which must be kept under con­trol to pro­tect indus­try, towns and com­mu­ni­ties. In many places flood atten­u­a­tion struc­tures (FAS) are designed and con­struct­ed for this pur­pose. Cur­rent­ly, such struc­tures are designed for a 1 in 100 year storm event. The con­trol­ling dis­charge sys­tem must be secure to guar­an­tee reli­able oper­a­tion dur­ing intense storm conditions.

A study car­ried out by the Water Author­i­ties found that dur­ing thun­der storms motor-dri­ven pro­tec­tion sys­tems tend to unre­li­able ser­vice. Time-con­sum­ing ‘on-site’ main­te­nance is then required. Such faults mean that an FAS is not always able to ful­fil its task in the time avail­able. How­ev­er, accord­ing to the same study, exter­nal ener­gy-free, low-main­te­nance units are the answer to this problem.

The Way

It makes sense to utilise the avail­able stored water ener­gy in the struc­ture to dri­ve the FAS flow con­trol, thus ren­der­ing elec­tri­cal equip­ment and expen­sive cabling unnec­es­sary. This not just eas­es the main­tain­ing authority’s bud­get – it is also an ener­gy-sav­ing mea­sure, reduc­ing the impact on nature and lend­ing the project an out­stand­ing eco-balance.

The Solution

The design of the inno­v­a­tive Hydro­Maxx Disharge Flow Con­trol is based on the proven effi­cien­cy of the HydroSlide Reg­u­la­tors. Hydro­Maxx is an active flow con­trol unit, mount­ed on the upstream face of an atten­u­a­tion sruc­ture wall. It takes the form of a mov­able plate con­trolled by a spe­cial­ly designed and patent­ed reg­u­la­tor mech­a­nism using a ver­ti­cal­ly mov­ing float whose move­ment keeps the flow con­stant irre­spec­tive of water lev­el. The float oper­ates ver­ti­cal­ly with­in the unit and trans­mits the water lev­el to a robust chain dri­ve which, in turn, acti­vates a sep­a­rate con­trol unit with two counter-rotat­ing con­trol plates. These con­trol plates reg­u­late the dis­charge auto­mat­i­cal­ly rel­a­tive to the impound­ing head – with­out exter­nal energy.

Even dur­ing max­i­mum impound­ing all plates and pro­tec­tive fea­tures can be man­u­al­ly adjust­ed safe­ly from ground lev­el to increase or reduce the dis­charge rate if desired.

The patent­ed Hydro­Maxx Dis­charge Flow Con­trol is housed with­in a high tow­er con­struc­tion, inte­grat­ed into the atten­u­a­tion struc­ture. The design of the inlet chan­nel should incor­po­rate a trash screen to pro­tect the flow con­trol unit from large debris such as tree trunks and boulders.

The Advantages

• con­stant dis­charges ±5%
• exter­nal energy-free
• no pow­er sup­ply costs
• low-main­te­nance
• ver­ti­cal­ly-mov­ing float pro­vid­ing reduced footprint
• space-sav­ing, ver­ti­cal­ly-oper­at­ing shields and plates
• inte­grat­ed bot­tom outlet
• emer­gency bulk­head oper­a­ble from above ground
• on-site adjust­ment of discharge
• max­i­mum hydro­sta­t­ic head. 16 metres