Foreword
"FIM" filters are designed to eliminate the turbidity of well water and surface water (rivers, lakes, etc.) due to physical impurities. In general FIM filters do not remove the turbidity due to not oxydized iron and manganese, thin colloidal matters not the colour due to thin colloidal matters, dissolved chemicals and organic compunds.
As an optional FIM filters can be equipped with dosing
systems of chemicals needed to improve flocculation and filtration of fines.
The filtreation bed is designed in such a way that the entire volume contribute to the
filtration process and not only the surface.
The first layer in contact with water consists of antracite in granular of proper size
which permits to achieve filtration degree of 5 microns.
Filter description
The filter is cylindrical vertical type, complete with
menhole in the lower part and inlet/outlet nozzles, drain, supporting legs and lifting
eyehooks.
The filter is built incarbon steel.
The wetted surface is sand blasted to white metal (SA2.5) and painted with two coats of
food grade paint.
The external surface is sand blasted and coated with primer and two finishing coats of polyurethane paint RAL 5015.
The water enters from the bottom side through a distributor
consisting of a central header and arms calibrated slots.
The filtered water distributor outlet is installed on the upper part of the filter.
Model FIM 180 (and larger) the inlet distributor consists of a plate fitted with
filtration nozzles and one additional menhole is provided.
The filter piping system consists of five diaphragm valves
with hydraulic or pneumatic actuators, two flow limiting devices. Two manual brass ball
valves are provided for air venting and water drainage respectively.
Two pressure gauges, with isolating valve, are fitted at filter inlet and outlet.
Piping and fittings are in galvanized steel.
For models FIm 180 and larger butterfly valves are used with pneumatic actuator. Valves
are in ductile cast iron and all piping is in welded carbon steel externally painted.
The control box includes one timer, one electromechanical
programmer, one rotating stager for opening/closing operations of the valves.
The service water is directly supplied from the inlet pipe through an on-off valve and a
cartridge filter.
Choosing the "FIM" filter.
The selection of the FIM filter isa related to type and concentration of the suspended particles in the raw water.
The turbidity shall not excede the value of 100 mg/lt (as
SiO2) and, within such maximum limit, the higher the raw water turbidity, the lower has to
be the specific filtration rate in order to avoid plugging and too short filtration
cycles. In fact if velocity is too high the suspended particles are deposite on the
external surface while internal strate of filtering media are practically unused.
If turbidity value is higher than 40 mg/lt and where in line floculation is produced by
coagulant injection, the raw water flow shall be kept at the lowest value reported in the
table.
Only if turbidity value is low (about 10 mg/lt) the highest flow rate can be selected.
The 24 hrs. cycle can be considered as normal. This is the cycle suggested duration in order to limit the pressure drop through the filter and to optimize the removal of particles during washing operation.
For the standard version of FIM filters the washing operation is made with raw water at the rates indicated in the table (lower rates may be not sufficient to restore the filter efficiency)In same cases it is necessary to use filtered water for the washing operation. In such cases an adequate pumping system shall be installed and connected to the unit control system.
OPERATING DATA:
- Min/max. operating pressure: 2-5 bar
- Min/max. water temperature: 5-40 °C
- Supply voltage/frequency: 220/50 V/Hz
- Power absorbed: 20 Watt
- Compressed air : 5 bar
