Free flow Dam Buster sumps revolutionize another critical area of roof drainage

Free flow Sumps don't require the water level to rise in the box gutter before they operate in the overflow condition.  In fact they operate hydraulically in exactly the same way as the revolutionary Dam Buster rainhead.  

This makes them much easier to design and install than the code specified ‘Sump / high capacity overflow’ to AS/NZS 3500.3-2018. They can also be safely used in lieu of the code specified Sump / side overflow devices.  

If the first chamber of the Dam Buster free flow sump is overwhelmed, or if the first chamber blocks with debris, the water just crests the internal weir and flows into the second chamber where it is safely disposed of via a second down pipe to atmosphere.  An additional overflow to atmosphere can also be fitted to the second chamber if required, therefore providing multiple redundancy.  

Like Dam Buster rainheads, Dam Buster sumps are all ‘pre-designed’ and fully engineered.  Just just like the rainhead too, the appropriate size of the sump device is simply selected from a table based on the design flow rate in litres per second.  You can find the tables in our Product Technical Statement which is available from Technical Downloads

Unlike existing sumps made by all other manufacturers, box gutters discharging to a Dam Buster Sump are designed for genuine ‘free flow’ in accordance with Figure I1 of AS/NZS 3500.3-2018, in both the normal and overflow conditions.  This also means the box gutter can be designed independently of the sump i.e similar to the rainhead.   

Dam Buster free flow sumps come factory made in 100mm size increments to suit all sizes of box gutter between 200mm and 600mm.  They can be easily fitted to virtually any box gutter, whether new or retrofit and are part of the integrated Dam Buster roof drainage system.  

Please Contact Us for more information.

Standard free flow sump installation example

Standard free flow sump installation example
Free Flow sump installation example

Free Flow sump installation example

At this stage all models are crafted in Zincalume, but quality powder coating is available and they can also be made in Colorbond, stainless steel, Colorbond Ultra or any other suitable sheet metal material. 

Potential uses of these amazing devices are limited only by the imagination, but include:

  • They easily replace standard code sumps - Dam Buster sumps are much simpler, perform far better and are also potentially a lot cheaper
  • Multiple sumps can be used along a single box gutter, including over very long distances. Extra redundancy is also built in along the length by cutting down the end wall of the overflow chamber in accordance with the Dam Buster Installation Manual. 
  • They provide extra versatility in roof drainage design.  As an example, they can be installed where a rainhead cannot be used due to the presence of a window or door below; in this case both the normal and overflow downpipes can potentially also be concealed and directed internally away from the sump location.  

NOTE: A Performance Solution is required for installation certification purposes of Dam Buster free flow sump devices; that document should be developed by a suitable expert such as a qualified hydraulic engineer, in accordance with the requirements of the National Construction Code. Documentation to assist the development of a Performance Solution can be found here at Technical Downloads

Sump with additional indicator overflow fitted

Sump with additional indicator overflow fitted

Check Out How the Dam Buster Free Flow Sump Works!


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