Pentair Fleck 5800 LXT - Page 32

Installer manual Fleck 5800 LXT - System sizing
32 / 96 Ref. MKT-IM-005 / F - 30.04.2020
• 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 [
→
Page33].
Q
draw
: injection draw flow rate [L/min]
Tip
Multiply the amount of salt in kg by 3 to get a approximation of the brine volume to
draw!
To calculate slow rinse duration:
The volume of water to be used for slow rinse is given in the resin manufacturers specifications.
Generally speaking, it is advised that between 2 and 4 BV of water is used to perform the slow
rinse after brine draw. The slow rinse cycle allows brine to be pushed slowly through the resin
bed, allowing the resin to be in contact with brine for sufficient time and therefore to be
regenerated.
Refer to the injector curve at the common working pressure to determine the slow rinse duration.