Sand Media Technology
AGF FILTER - THE PRINCIPLE
Sand Media filters operate by separating the suspended materials in unfiltered water as it flows
through a bed of media in a pressurized tank.
The recommended filter medias - crushed basalt, quartz sand or catalytic media, have many
varying aperture sizes that cause the water to flow through a maze of passages on its way from
the inlet to the outlet of the filter.
Sand Media Technology
Due to the large volume and contact area between the water and the media/gravel
particles, various physical forces are put into effect and act to retain the contaminating
particles.
The efficiency of large particle retention is high as long as the gravel is kept clean.
The catalytic media type applies an additional chemical-physical attraction between
the media and particles - especially those of organic nature, giving more efficient
organic material separation. In addition, the round shaped particles degrade more
quickly and their cleaning requires less water in comparison with other media types.
Filtration Process
During the filtration process, unfiltered
water enters the media filter system
via the inlet manifold. It is cleaned by
flowing through the media and discharged via the outlet manifold.
During filtration the inlet ports are open and the backwash ports are closed.
Water flows from the top, over the diffuser, then down through the media layer
to the outlet through the "mushrooms" located in the bottom part of the filter.
Backwash Process
During the backwash process the inlet port closes and the backwash port
opens, allowing reverse water flow into the filter.
Clean pressurized water from the other filters now flows into the bottom of the
filter, lifting the media and freeing the accumulated dirt and debris that is then
flushed out through the backwash valve and into the backwash manifold.
If the backwash restriction valve is adjusted properly, the debris will be flushed out of the filter while the media, being of a
higher bulk density than the debris will remain fluidized in the filter tank.
Only one filter at a time should backwash. The water that is being used to backwash one filter would have already passed
through another filter or filters so that the backwash process is carried out with clean, filtered water.
Inlet port
Backwash valve
Backwash port
Inlet
To outlet manifold
Inlet port
Backwash valve
Backwash port
Inlet
To outlet manifold
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