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Sand / Anthracite FAQ’s
What is a Sand Anthracite filter
A sand anthracite filter or multi-media filter consists of 3 main parts:
- a composite pressure vessel
- a sand-anthracite filter control valve (usually low voltage)
- graded beds of sand and anthracite
The water filters down through the sand-anthracite filter media, up through a riser tube in the centre of the composite pressure vessel and out through the sand-anthracite filter control valve to service.
Periodically, the sand-anthracite filter will backwash, which changes the water flow through the sand-anthracite filter. The water in the backwash cycle flows in from the inlet, down the centre riser tube, up through the sand and anthracite bed, and out of the control valve to drain.
The next step in a sand-anthracite filter regeneration cycle is rinse. The water in a rinse cycle of a sand-anthracite filter flows as in service, down through the composite pressure vessel and sand-anthracite filter media and up through the centre riser tube, through the sand-anthracite filter control valve and to drain. The sand-anthracite filter then returns to its normal service position.
Please note that the above relates only to the smaller simplex sand-anthracite filters which we supply. For other types of sand-anthracite filters, such as multi-media filters, duplex sand-anthracite filters, triplex sand-anthracite filters and cartridge sand-anthracite filters, please contact us.
How does a Sand Anthracite filter work
Multimedia or sand anthracite filtration is a proven design concept; the coarse media layers in the top of the tank trap large particles, and successfully smaller particles are trapped in the finer layers of media deeper in the bed. The result is a highly efficient filtering since removal takes place throughout the entire bed. Multimedia filters typically remove particles 5 to 15 microns in size or larger as opposed to a conventional single media sand filter which removes 30 micron or higher. What are the advantages of using a Sand Anthracite filter
What is Sand
The sand in a sand filter (#20 silica sand; 45-55 mm) is specially graded to trap particles in the 20-100 micron range. As a sand filter collects dirt, its efficiency increases, trapping more dirt.
What is Anthracite
Filtracite is selected, naturally-hard, clean Welsh Anthracite, the finest in the world. It is an excellent filtration medium for gravity and pressure filters, for the treatment of hard and soft water, sewage, oil, acid/alkali liquids. The hardness of Filtracite ensures minimum wastage by attrition in service. Filtracite is practically free from water-soluble constituents and mineral matter other than the low inherent ash content of the specially selected anthracite from which it is made. It contains over 90 per cent of pure carbon, and its low silica content is a decided advantage in the treatment of alkaline waters for boiler feed purposes.
The irregular shape of the particles offers a larger surface area per unit of volume and larger spaces between particles, which enable high filtration rates with low head losses to be obtained. The greater surface area of Filtracite promotes the efficient removal of algae, turbidity and bacteria. Filtracite’s low bulk density, coupled with the irregular and angular shape of a densely packed bed: thus the whole depth functions as a filter and not merely the top part, as with other closely-packing materials.
Advantages
- Faster filtration
- Longer filter runs
- Low loss of head
- Economic use of space
- Long life
- Savings in wash water
- Big capital savings
- Easy to handle
- Available in several sizes
Anttracite is beneficial for rapid gravity and pressure plant, and for tackling oils, acids and alkalis. A prime benefit of anthracite and sand filter beds is that filtration in depth can be applied to existing as well as new filtration plant. The main improvement resulting from dual media beds is the reduction in the rate of head loss build-up at a given filtration rate. Thus, the length of filter runs can be up to three times that achieved with a conventional sand bed, or filtration rates can be increased while yielding acceptable lengths of run and, overall, the incorporation of anthracite and sand media can double nominal filtration capacity.
Filtration has been chosen for many installations by the Water Authorities in Britain and it is in steady demand from leading chemical companies. Filtracite is exported all over the world
What will Sand remove
Sand filters remove 99.99% of bacteria, viruses, Giardia, and Cryptosporidium, are approved for surface water treatment, have no power or chemical requirements, and have gravity feed hydraulics. Optional additions include Granular activated carbon for pesticides, THM removal, calcite to raise pH, and UV or ozone for second barrier protection.
What will Anthracite remove
A sand-anthracite filter or dual media filter/multi-media filter is primarily used for the removal of turbidity and suspended solids as low as 10-20 microns.
How long will my Sand Anthracite filter last
It is usual that a sand anthracite filter could last up to ten years,However the media inside the vessel could require changing more often than that dependant upon the quality of the incoming water .It is advisable to have a reputable firm to service the sand anthracite filter and check the water quality.
How long is the guarantee on my Sand Anthracite filter
All our sand anthracite filters have a one year parts warranty as standard
Do I need my Sand Anthracite filter servicing
It is advisable to have smaller sand anthracite filters such as domestic applications serviced once per year and larger industrial units twice per year. Please contact our service department for full details.
What incoming water parameters does the Sand Anthracite filter require to work correctly
Inlet water pressure minimum of 1.5 Bar
Inlet water pressure maximum of 8 Bar