Material: uPVC (unplasticised PVC)
Certified for use with potable water? Yes (certified to AS/NZS 4020)
Compatible Downpipe Systems: 90mm/ 100mm Stormline® stormwater pipe. Adaptors available for use with RP80® 80mm and RP65® 65mm downpipe.
GUIDE TO CALCULATING THE SIZE OF DIVERTER REQUIRED
Step 1 – Calculate the amount of polluted water to be diverted
(Roof Area x Pollution Factor) + (Length of wet pipe x pipe cross-section factor) = litres to be diverted
Roof Area x Pollution Factor = litres to be diverted
Roof Area = length x width in m2 of actual roof area draining into the water tank system.
NB. This is not the floor area of a house. Need to calculate the area of each roof section draining into the water tank and then add them together to get the total roof area
Pollution Factor = the level of water pollution likely in the particular environment.
This differs depending on the surrounding environment i.e. flora and fauna. There are three approximate pollution factors that can be applied:
|Minimal Pollution||Open field||0.5|
|Average Pollution||Some trees & shrubs in neighbourhood but not directly adjacent to collection area||1|
|Substantial Pollution||Trees and foliage on and around property. Leaves, debris, bird droppings, various insect matter||2|
Length of Wet Pipe = in a wet system water is held in the pipes and will grow stagnant over time. Therefore this water also needs to be flushed before it enters the tank and so the volume contained in the pipes needs to be allowed for in the calculations.
Pipe cross-section factor = as per above the volume of water in the pipes of a wet system needs to be allowed for in the calculations. To calculate this for different diameter pipes, the Length of Wet Pipe is multiplied by the Pipe Cross Section factor.
|PIPE SIZE||PIPE CROSS SECTION FACTOR|
|Marley RP65® 65mm round downpipe||3.30|
|Marley RP80® 80mm round downpipe||4.40|
|Marley Stormline® 90mm stormwater pipe||5.75|
|Marley Stormline® 100mm stormwater pipe||8.60|
Step 2 – Choose the appropriate First Flush Diverter and Chamber length required
|PRODUCT||LENGTH OF CHAMBER||VOLUME IN LITRES|
|90mm First Flush Diverter||1 metre||5.7 litres|
|2 metres||11.4 litres|
|3 metres||17.1 litres|
|300mm First Flush Diverter||1.5 metres||112 litres|
|2 metres||147 litres|
NB. The 90mm First Flush Diverter is usually installed on each downpipe that feeds into a tank whereas the 300mm First Flush Diverter has a much larger capacity and can handle feeds from either single or multiple downpipes.
Slow Release Valve
The slow release valve ensures the first flush chamber empties itself after rain and resets automatically.
The slow release valve is a simple automatic system that does not rely on mechanical parts or manual intervention. As the water level rises in the diverter chamber, the ball floats, and once the chamber is full, the ball rests on a seat inside the diverter. The Ball prevents diverted water from escaping back into the main flow.
The Slow Release valve begins draining water the moment water enters the diverter chamber and is continuous.
Negative pressure created by the continuous release prevents contaminated water from escaping between the ball and seat for the duration of the rain event.
The optimum drain rate is between 4 and 15 litres per hour.
The Downpipe First Flush Diverter is supplied with eight Flow Control Washers. Each of the eight washers incorporate different sized drain holes ranging from 0.25mm to 2.0mm. Washers are exchanged to achieve optimum flow from the chamber.
Optimum flow is defined as, the slowest reliable flow. As a guide, small drain hole washers are installed in low pollutions environments; larger drain hole washers are exchanged in higher pollution environments to prevent blockages between maintenance.
The following table details flow rates under controlled conditions; clean water. The flow rate for each washer will vary in environments with increased pollution.
The Marley First Flush Diverter system includes technical elements, to ensure optimal performance Marley recommends you use a trade professional for installation.
For further information please consult the Marley Rain Harvesting Systems brochure.
To ensure continuing function, unscrew the cap on a regular basis to allow debris to fall out. Hose or wash the filter if needed and check and clean the flow control valve.