16
Vertical Pressure Filters, media ratios
The make-up of the pressure filter bed depends upon the size of the filter and configuration of the base, there are four
options.
1.
2.
3.
4.
Filters under 1m diameter with laterals.
Filters under 1m diameter with nozzle plate.
Filters over 1m diameter with laterals.
Filters over 1m diameter with nozzle distribution plate.
Anthracite may be used on top of the AFM® to extend the run phase cycle and allow the AFM® to cope with high loadings
of solids. Activated carbon may be used for dechloramination, removal or other applications discussed in next section.
Table 1.Vertical pressure filters; AFM® filter bed depths as a percentage for each grade for
Vertical pressure and gravity flow Filters, bed depth may range from 600mm to 1400mm
Grade 3 Grade 2 Grade 1 Grade 0 anthracite
Back-wash
velocity
0%
0%
10% 20%
10%
10% 80%
90%
80% 0%
0%
0%
>45m/hr
>45m/hr
>45m/hr
0% 10% 90% 0% >45m/hr
0% 10% 0% 70% 20% >20m/hr
Pressure filters over 1m Ø with nozzle plate & 0%
RGF filters with nozzles or screened floor
AFM® grade 1 multi-layer with anthracite
Backwash at >45m/hr velocity
Pressure filters under 1m Ø with nozzle plate
0% 10% 0% 70% 20% >20m/hr
10% 70% 0% 20% >45m/hr
Pressure filters over 1m Ø with nozzle plate &
RGF filters with nozzles or screened floor
No flocculation, Pressure & RGF filters
Pressure filters, under 1m Ø with laterals
Pressure filters under 1m Ø with nozzle plate
Pressure filters over 1m Ø and RGF filters with
laterals.
Pressure filters over 1m Ø with nozzle plate &
RGF filters with nozzle plate
AFM® grade 0 optimised filters 0% 10% 70% 0% 20% >45m/hr
0%
0%
10%
20%
10%
10%
60%
70%
60%
20%
20%
20%
>45m/hr
>45m/hr
>45m/hr
0% 10% 70% 20% >45m/hr
Grade 0 optimised filters, pressure filters under
1m Ø with laterals
Grade 0 optimised filters, pressure filters under
1m Ø with nozzle plate
Grade 0 optimised filters, pressure filters over
1m Ø with laterals
Grade 0 optimised filters, pressure filters over
1m Ø with nozzle plate and RGF filters 0% 20% 10% 70% >20m/hr
0% 10% 10% 80% >20m/hr
10% 10% 10% 70% >20m/hr
0% 10% 10% 80% >20m/hr
With (or without) flocculation, Pressure
& RGF filters
Pressure filters, under 1m Ø with laterals
Pressure filters under 1m Ø with nozzle plate
Pressure filters over 1m Ø and RGF filters with
laterals.
Pressure filters over 1m Ø with nozzle plate &
RGF filters with nozzles or screened floor
AFM® grade 0 multi-layer with anthracite
Back-wash at >20m/hr velocity
Pressure filters under 1m Ø with nozzle plate
0.6 to 1.18mm
0.6 to 1.18mm
1.18 to 2.5mm
1.18 to 2.5mm