Installer Manual Fleck 4600 - MECH - System sizing
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Ref. MKT-IM-027 / B - 01.06.2018
4.2.2. Determining the required volume of resin
When sizing a softener, make sure that the volume of resin in the tank (bed volume) will be sufficient
so that even when the peak flow rate is reached, the velocity is still between the above values
depending on the hardness. When sizing a softener, always choose the resin volume and tank size
based on the peak flow rate but not on the nominal flow rate.
Note
Sizing on the nominal flow rate without taking the peak flow rate into account would result
in choosing smaller tank size and resin volume, and may lead in severe hardness leakage
during the service cycle when the peak flow is reached.
The maximum softened water flow rate that a softener can produce is given by the following formula:
Knowing this required volume of resin, it is possible now to determine the tank you need. Note that at
least a third of the total volume of the tank must be kept as free space so that the bed expansion
during backwash is sufficient to ensure correct cleaning of the resin.
1.25
32
8.69
1.5
40
13.57
2.0
50
21.20
2.5
63
34.2
3.0
75
49.2
Q
service max
= Fs
service
x BV
with:
Q
service max
: service flow rate [m
3
/h]
Fs
service
: service velocity [BV/h]
BV: bed volume of resin [m
3
]
Piping size (internal diameter)
Max. flow rate
[in]
[mm]
[m
3
/h at 3 m/s]
