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Copyright Valsir-Uneeq 2013
Valsir-Uneeq - 49 Brunton Circle, Foundersview South, Modderfontein - Gauteng - South Africa
Rainplus is a siphonic rainwater drainage system designed to reach maximum drainage performance with the lowest levels of water accumulation on the roof. Valsir Rainplus  fully meets the demands of increasing rainfall levels being registered and guarantees the drainage of rainwater from medium to large size buildings in total safety. The system uses the building height as the driving force to generate high speed flow rates thus maximizing drainage efficiency. Rainplus  allows the entire quantity of rainwater to be directed to any part of the building whatsoever thus enabling the implementation of the most modern rainwater harvesting systems. The harvesting and conservation of water are parameters that are taken into consideration and contribute to obtainment of Green Building marks.
The advantages of this technology are numerous; such as the significant reduction in costs and installation times, as well as an increase in the performance of the entire drainage system. The Rainplus siphonic system is made up of special roof outlets that are designed and tested according to American Standard ASME A112.6.9 and European Standard EN 1253. These outlets are connected to Valsir HDPE pipes and fittings, which are sized in order to work under negative pressures, at high flow rates and with a full bore. This is possible thanks to the special configuration of the Rainplus  roof outlets, which prevent air from entering the pipes when the design rainfall intensity value is reached. In this way, the hydraulic engine of the system is given by the height of the roof in relation to the drainage point and not by the amount of water that has accumulated on the roof.
The advantages of Rainplus
Economical. When compared to conventional systems, Rainplus requires a lesser number of roof  outlets and allows a substantial reduction  in pipe diameters, in the number of  fittings required and the number of  downpipes: this results in savings of up to 80% on vertical pipes and from 20% to  30% across the entire system.
Space saving.  The roof outlets are connected to  single horizontal collector pipes that  are fitted without fall and the  downpipes are positioned anywhere along the building perimeter thus  avoiding interference.
High performance.  When in operation drainage pipes flow at  100% full over the entire system, draining  velocity is therefore greater resulting in  the self cleaning action of the pipework.
Eco sustainability.  The ease in directing the pipes to  storage tanks makes the collection  of rainwater easier for reuse in  irrigation systems, fire ponds and  tanks for non-potable uses in  general.
Time and labour saving.  Construction programmes are accelerated due to reduced installation times and less  groundwork is required due to the  reduced number of embedded pipes.
Increased design flexibility.  Complete control over downpipe  location and absence of embedded  pipes gives increased design flexibility  of the siphonic system.
The Valsir Rainplus system and HDPE are produced with completely recyclable materials which, at the end of their useful life can be recovered. The production processes employed are energy efficient and of reduced impact. Valsir has adopted the Green Building principles in terms of respect for the environment and conservation of resources, pipes and fittings are in fact certified by the prestigious Singapore Green Building.
Conventional Rainwater Drainage Vs. RAINPLUS Siphonic Rainwater Drainage
A conventional drainage system can be designed for large  surface areas but does not cut off air flow into the pipe. For  this reason pipes are sized for filling ratios of 20% or 33%  (depending on national or local standards and regulations)  allowing considerable amounts of air into the pipes of 80% or 67% of the pipe section. In conventional roof drainage, the  outlets are simple funnels installed on the roof covering and  connected to the downpipes which are as high as the  building and the water collectors which require a gradient of  at least 1%, are dimensioned for a maximum filling factor of  70%. When the water collectors are very long and it is not possible to provide the minimum slope necessary due to the limited  space available, the only solution is to increase the size of the pipes with a consequent rise in installation costs.
The Rainplus siphonic drainage system is made up of special outlets that incorporate an anti-vortex plate that prevents air  entering into the pipes. The outlets are connected via short  pipes of relatively small diameters to the horizontal water  collector which is located just under the building roof. The collector pipe, generally installed at the highest possible  position, runs horizontally (no fall angle is required) untill it  reaches connection with the downpipe. The downpipe drops  into the drainage line which is buried in the ground and  conveys the water straight into a collection tank or the  municipal stormwater mains. The absence of air in the system allows it to run 100% full of  water making use of the entire pipe section and vastly  increasing flows that are 10 times faster when compared to  conventional drainage systems.
Drainage Systems