Installer manual Fleck 3150 NXT/NXT2 - System sizing
Ref. MKT-IM-010 / C - 18.10.2019
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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 liter 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 liter;
• 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 liter 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 in [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
Summary of Contents for FLECK 3150 NXT
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