Pentair FLECK 3150 NXT, Installer Manual

Page: 32 / 182

Installer manual Fleck 3150 NXT/NXT2 - System sizing
32 / 182 Ref. MKT-IM-010 / C - 18.10.2019
Info
Preprogrammed cycle times are only factory default programming that need to be
adjusted to fit the system requirements.
For cycle time calculation the valve configuration must be known, which depends on:
• the tank size;
• the resin specifications for the velocity for backwashing the resin bed;
• the velocity of water for brine draw, slow rinse and fast rinse.
Further information needed for cycle time calculation are:
• the resin volume previously determined;
• the salt amount used per regeneration;
• the volume of water to use for backwash, brine draw, slow rinse and fast rinse.
To calculate the backwash duration:
Tb
ackwash
= (N
BVbw
× BV) / Q
DLFC
with:
T
backwash
: backwash duration [min]
N
BVbw
: number of bed volume for backwash
BV: bed volume [L]
Q
DLFC
: drain line flow controller size [L/min]
Info
The typical value of the volume of water to be used for backwash is between 1.5 and
4 times the bed volume, depending on the inlet water quality.
To calculate the brine draw duration:
Knowing the injector draw flow rate at the working pressure:
T
brine draw
= V
brine
/ Q
draw
with:
T
brine draw
: brine draw duration [min]
V
brine
: brine volume to be drawn [L], see Refill
calculation
Q
draw
: injection draw flow rate [L/min]
Info
Multiply the amount of salt in kg by 3 to get a approximation of the brine volume to
draw.