Pentair Siata V132 SFE, Installer Manual

Page: 28 / 88

Installer manual Siata V132 - SFE - System sizing
28 / 88 Ref. MKT-IM-003 / B - 19.04.2017
4.2.4. Valve configuration
Knowing the volume of resin, tank size and specifications of the resin, it is possible to determine the
required valve configuration. The resin specification will give the backwash velocity, as well as the
brine draw and slow rinse velocity that must be respected in order to ensure a proper regeneration of
the unit. From this data, determine the required backwash flow rate as well as the brine draw and
service flow rate. In most cases, the fast rinse flow rate will be the same as the backwash flow rate,
however for certain valve types the fast rinse flow rate will be the same as the service flow rate.
To determine the backwash flow rate:
Q
backwash
= Fs
backwash
x S
The DLFC installed on the valve has to limit the backwash flow rate to the above calculated flow rate.
To determine the injector size:
The velocities to be respected for brine draw and slow rinse are given on the resin manufacturer
specifications. Generally speaking, the injector has to allow a flow rate of about 4BV / h
(corresponding to the flow rate of brine being drawn added to the flow rate of raw water passing
through the injector nozzle to create the suction effect).
Q
Inj
= 4 x BV / h
Note

This value does not correspond to the brine draw flow rate but to the total flow rate passing
through the injector. Then refer to the injector diagrams for the chosen tank size and at the
inlet pressure in order to check if the injector will give a correct flow rate. See “Injection flow
rates (tables)”, page 31.
with:
Q
backwash
: backwash flow rate [m
3
/h]
Fs
backwash
: backwash velocity [m/h]
S : area [m
2
]
with:
Q
inj
: total flow rate passing through the injector [L/h]
BV : bed volume of resin [L]
A