SUPADIVERTA - syphonic rainwater diverter

GARDENS

INLINE FILTERS

Varying manufacturers inline filters are similar in performance but AQUATREK recommends the HOLMAN product for the following reasons:-

• The internal filter cartridge is made from a tough but flexible white plastic that clearly shows any trapped sediment. Many other filters are black and have proven difficult to judge where cleaning is best concentrated.
• The HOLMAN filter is available in three end sizes, 13mm, 19mm and 25mm. Both ends are removable and size interchangeable, allowing the filter to join different size hoses. The convenience and advantage of clever design is obvious.

Most filter cartridges have mesh aperture sizes ranging from 80mm to 175mm. Manufacturers unfortunately rarely indicate the filter mesh size. A choice and indication of size would be an advantage to consumers.

While suitable for use with mains water, INLINE FILTERS ARE NOT SUITABLE FOR USE WITH RAINWATER HARVESTING SYSTEMS as the internal filter cartridge presents a physical barrier which reduces velocity and the more contaminants it traps, the more restricted it becomes.

LOW COST DIY FILTER

It is easy to make a simple inline filter that can extract about 60% of the remaining finer debris passing from the Supadiverta to a tank. It is also good for gardeners feeding to gravity fed drip hoses.

As per the example if using horizontal 40mm PVC pipe; buy…

• One 40mm Tee.
• One 40mm Elbow.
• One 40mm X 20mm reducing bush.

Join the Tee and Elbow with a short length of 40mm PVC pipe.
Push the reducing bush into the elbow.
Fit the Tee and Elbow (with the Elbow at the bottom) between the 40mm PVC horizontal pipe. Fit the Tee as far as possible downstream from other Elbows, Tees or pipe size changes to avoid turbulent flow.
Connect the required length of 20mm PVC pipe into the reducing bush.

The 20mm PVC pipe could then be either connected to a 25mm polypipe fitted with an inline tap or the 20mm PVC pipe could be fitted with 45 degree elbows and brought to the surface. A PVC ball valve fitted to the end would then allow manual draining.

OF INTEREST:
Water flowing through a pipe travels faster through the core and slower on the outside extremity due to wall friction loss and the resultant separation zones or streamlines is known as laminar flow.
About 90% of the debris travels slowly along the bed load provided the flow is laminar and not turbulent. The inverted Tee will capture much of this bed load.
A raised bottom projection causes the flow to speed up to pass over the obstacle. This results in an eddy (vortex) circulating on the lee side and becoming a bed load trap by holding low inertia particles in eddy suspension and is why underwater obstacles, large rocks for example, cause downstream deposits of thick mud where an eddy has formed. Gold prospectors know these areas well!
By forming a small narrow ledge across the bottom of the upstream pipe, the efficiency of the sediment trap can be improved. This type of filter is known as an Induced Vortex Sediment Separation filter.
The distance from the obstruction to where the vortex forms is governed by the size and height of the obstruction and the flow velocity. If making an obstacle to induce eddy suspension in a pipe with variable flow rates, the obstacle must be small otherwise much of the debris could ‘overshoot the mark’. A height of 1.5 mm is sufficient.