First flush diverters

First Flush Diverters divert the sediment that builds up on roofs between rainfalls away from collection tanks.

  • 90mm option for in-line installation on individual downpipes
  • 300mm size for filtering the flow from multiple downpipes
  • Purchase chamber separately to suit requirements
  • Reduces contamination of tank water

 

Why Marley?

15 year guarantee

We stand by our product, and back it for 15 years

Will not rust / corrode

Designed for NZ’s salt-laden coastal air

UV resistant

UV resistant to handle NZ’s harsh summer sun, high UV levels and long, hot days

100% Recyclable

Used spouting and downpipes can be returned to Marley for recycling

Made in NZ

Proudly made in New Zealand for over 40 years

Components

 PRODUCTSCODE

KIT:

First Flush Diverter Kit 90mm

RH8119-5

KIT CONTAINS:

T-Junction

- - - -

80/90mm Adaptor x 2 (NB: Code is for one)

KO591

Ball seat

K0006

Sealing ball

K0014

Fine filter

K0036

Threaded coupling/socket

K0009

O’Ring seal

K0003

Screw end cap

K0012

Washers Red – Set of 4 (1.25 to 2mm aperture)

K0002

Washers Black – Set of 4 (0.25 to 1mm aperture)

K0376

Nut

K0005

Tail

K0004

Pipe bracket x 2

- - - -

Chamber Options:
(Sold Separately)

90mm x 1m Stormline Pipe (Volume 5.7L)

700.90.1

90mm x 3m Stormline Pipe (Volume 5.7L per m)

700.90.3
 PRODUCTSCODE

KIT:

First Flush Diverter Kit 300mm

RH8121-1

KIT INCLUDES:

Chamber end cap x 2 (NB: Code is for one)

K0018

Ball seat

K0006

Sealing ball

K0014

Primary filter

WDAC02

Fine filter

K0036

Threaded coupling/socket

K0009

O’Ring seal

K0003

Screw end cap

K0012

Washers Red – Set of 4 (1.25 to 2mm aperture)

K0002

Washers Black – Set of 4 (0.25 to 1mm aperture)

K0376

Nut

K0005

Tail

K0004

Galvanised post bracket

- - - -

Pipe bracket

- - - -

Chamber Options:
Sold Separately

300mm x 1.5m Chamber (Volume 112L)

FFD.300.1.5

300mm x 2m Chamber (Volume 147L)

FFD.300.2

Resources

Technical Details

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

Wet System
(Roof Area x Pollution Factor) + (Length of wet pipe x pipe cross-section factor) = litres to be diverted

Dry System
Roof Area x Pollution Factor = litres to be diverted

Definitions
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:

CATEGORYDESCRIPTIONPOLLUTION FACTOR
Minimal PollutionOpen field0.5
Average PollutionSome trees & shrubs in neighbourhood but not directly adjacent to collection area1
Substantial PollutionTrees and foliage on and around property. Leaves, debris, bird droppings, various insect matter2

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 SIZEPIPE CROSS SECTION FACTOR
Marley RP65®  65mm round downpipe3.30
Marley RP80®  80mm round downpipe4.40
Marley Stormline® 90mm stormwater pipe5.75
Marley Stormline® 100mm stormwater pipe8.60


Step 2 – Choose the appropriate First Flush Diverter and Chamber length required

PRODUCTLENGTH OF CHAMBERVOLUME IN LITRES
90mm First Flush Diverter1 metre5.7 litres
2 metres11.4 litres
3 metres17.1 litres
300mm First Flush Diverter1.5 metres112 litres
2 metres147 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.

flow control

INSTALLATION

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.

MAINTENANCE

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.

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