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Transferring the AFM® to the filter
AFM® may be transferred manually to the filters by emptying the plastic bags, or 1 tonne big bags into the filter in
accordance with the procedure below.
AFM® may alternatively be transferred to filters from a bulk tanker using water. Under no circumstances use compressed
air or transfer the AFM® in a dry condition. Under high air pressure and at high velocities, the AFM® would damage the
transfer hose which would cause contamination of the product.
How to fill Pressure filters
In all cases, it is essential that the filters are on a level concrete pad or plinth, and that the valve manifold and pipework is
supported to prevent any stress on the filter flanges.
Before the first layers of filter media are introduced via the top access port, it is best to half fill the filter with water. This
helps to prevent damage to the laterals or the nozzle distribution plate by the falling media.
For filters with a side manhole, open the bags and gently empty the first layer onto the base of the filter bed. The larger
grades are added first, grade 3 for filters over 1m in diameter, and grade 2 for filters 1m and smaller in diameter. See Table
1.
For horizontal filters, we also recommend grade 3 on the base of the filter up to a point that is level with the laterals.
After the addition of each layer it is important to make sure the media is evenly distributed and the bed is flat. Once all the
media is in place, perform a backwash in accordance to Table 3.
After the back-wash, inspect the bed, there may be fines on top of the bed. Carefully skim the top off the filter bed to
remove the fines and any other debris that may be present that could interfere with filtration performance. With AFM® this
is rarely required, but with a new installation there could be debris such as plastic shavings from the pipework and filter
installation.
Once the filter bed has been skimmed, refit the filter lid and backwash for a period of 5 minutes, or until the water runs
clear. After the back-wash, place the filter on a rinse phase for 2 minutes. Once the rinse phase has completed and if there
is sufficient water, repeat the backwash and rinse phase for a third time. The bed is now ready for service, however before
going on-line with a drinking water network it is good practice to conduct an analysis of the water in accordance with Annexe
1.
Anthracite and multi-layer beds
Anthracite or activated carbon may be used with AFM®, the choice of media depends upon the application of the AFM®.
Table 1, provides details on the use of anthracite with AFM® grade 0 and grade 1.
Grade 0 AFM® provides and exceptional performance in mechanical filtration of water. Grade 0 can also be used to treat
water with a heavy load of solids, or it can be combined with coagulation and flocculation. Under these conditions it is
necessary to use a layer of anthracite on top of the AFM® grade 0 bed to protect the media and to provide a longer run
phase cycle between back-washes