Installer manual Fleck 5600 SXT - System sizing
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Ref. MKT-IM-013 / E - 23.09.2020
Q
service max
= Fs
service
× BV
with:
Q
service max
: service flow rate [m
3
/h]
Fs
service
: service velocity [BV/h]
BV: bed volume of resin [m
3
]
Knowing this required volume of resin, it is possible now to determine the needed tank. 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.
4.2.3
Resin exchange capacity and capacity of the unit
The resin exchange capacity and capacity of the unit are two different things that should not be
confused. The resin exchange capacity is the amount of Ca
2
+ and Mg
2
+ that can be retained by
1 litre of resin, which will depend on the resin type and salt dosage, whereas the capacity of the
unit is the capacity of the system, which will depend on the volume of resin and resin exchange
capacity.
Knowing the required volume of resin, it is possible to determine the exchange capacity of the
unit. The capacity of the unit can be expressed in different ways:
• the mass capacity, which corresponds to the weight in equivalent CaCO
3
that can be fixed on
the resin, expressed in kg as CaCO
3
;
• the volume capacity, which represents the maximum amount of water that can be treated
between 2 regenerations. This last capacity takes into account the hardness of the water to
be treated and is expressed in m
3
or litre;
• the combined capacity, which represents the volume of water that could be treated between
2 regenerations if the inlet hardness is 1 °f or °dH. This capacity is expressed in °f.m
3
or
°dH.m
3
.
The resin exchange capacity will depend on the amount of salt to be injected into the resin bed
during the regeneration. This amount of salt is given in grams per litre of resin. The next table is
showing the resin exchange capacity in function of the amount of salt for a system with standard
efficiency regeneration.
Resin exchange capacity as a function of the salt dosage:
Salt amount
[g/L
resin
]
Corresponding resin
exchange capacity
[g/L
resin
] as CaCO
3
°f.m
3
[per L
resin
]
°dH.m
3
[per L
resin
]
50
29.9
2.99
1.67
60
34
3.4
1.9
70
37.5
3.75
2.09
80
40.6
4.06
2.27
90
43.4
4.34
2.42
100
45.9
4.59
2.56
110
48.2
4.82
2.69
120
50.2
5.02
2.8
130
52.1
5.21
2.91
