Pentair SIATA V132-SFE-EV-VIRIDION Installer Manual page 27

The below sizing method can be applied for both residential and industrial softeners.
The sizing of a softener must be based upon certain parameters:
• inlet water hardness;
• peak flow rate and nominal flow rate;
• service velocity;
• salt dosage.
The softening and regeneration reactions are driven under certain conditions. To allow these
reactions to take place, make sure that the velocity is convenient during the different phases for
proper ion exchange. This velocity is given in the resin manufacturer specifications sheet.
Depending on the inlet water hardness, the service velocity for standard softening must be between:
Service velocity
[bed volume per hour]
8 - 40
8 - 30
8 - 20
Note
Failure to respect the service velocity will lead to hardness leakage or even total softener
inefficiency.
Note that the water supply piping size may also be useful when estimating the nominal flow rate, since
the size of the piping allows a maximum flow rate to pass. Assuming the maximum velocity of water
in pipes is about 3 m/s, a good estimation for most common pressure [3 bar] and temperature [16°C]
is:
Piping size (internal diameter)
[in]
0.5
0.75
1
Ref. MKT-IM-009 / C - 08.06.2018
Installer Manual Siata V132-SFE-EV-VIRIDION - System sizing
Inlet water hardness
[mg/l as CaCO
<350
350 to 450
>450
[mm]
12
20
25
°f
]
°TH
3
<35
35 - 45
>45
Max. flow rate
3
[m /h at 3 m/s]
1.22
3.39
5.73
°dH
<19.6
19.6 - 25.2
>25.2
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