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13 Calibration (basic measurement adj
13.4
Calibration redox (mV)
The calibration for redox measurement is
calibration. A buffer solution with a known redox
used.
TIP
Redox calibration
Depending on water quality a
electrode, it can occur that the r
very slowly if it is moved from th
into the measuring water
disadvantageous conditions, it m
until the measured redox value
displayed correctly.
During that time, reasonabl
activation of redox control is not p
Therefore, it is recommended t
calibration when necessary, s
suspected that the electrode coul
Calibration can be omitted for th
order to avoid potential problems
Functioning redox electrodes g
tolerance range, such that calibra
display value by a few mV.
The absolute redox value is not o
the redox value to the chlorine va
important; see section =
13.4.1
Calibration procedure
Redox (mV) calibration can be found in the follo
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Calibration is carried out as follows:
•
Select 1'point Calibration Redox (mV)
•
Calibration is a menu sequence, i.e. it go
menus step'by'step.
13.4.1.1 Calibration Data
The following parameters are displayed in the c
Calibration value
For calibration value, enter the reference value
redox value of the buffer solution being used (e.
Current value
This is the current measured value calculated
from the last calibration, which are still valid. T
from the actual value. It is only displayed to giv
orientation throughout calibration.
Using the measured value, you can see wh
stabilised when you place the electrode into the
13.4.1.2 Calibration results
At the end of calibration, the calibration para
displayed:
Offset
Offset is the zero point shift calculated from ca
in [mV].
Current value
The redox (mV) measured value is now
parameters from the current calibration. T
displayed should therefore be consistent with
entered.
36
adjustment)
is performed as 1'point
dox value (e.g. 465 mV) is
and the state of the
e redox electrode reacts
the buffer solution back
after calibration. In
it may take several hours
e stabilises again and is
ble configuration and
ot possible.
d to only perform redox
, such as when it is
ould be defective.
r the following reasons in
ms with running'in time:
generally have a tight
libration only changes the
ot of significant. Assigning
value in the pool is more
"
' 9 * .,
ollowing menu:
goes through a series of
e calibration menu:
lue for calibration, i.e. the
(e.g. 465 mV).
ted using the parameters
d. This value may deviate
give you a certain level of
when measurement has
the buffer solution.
arameters calculated are
calibration. It is indicated
calculated using the
. The measured value
with the calibration value
13.4.1.3 Step by step
1.point calibration with buffer so
r solution (e.g. 465 mV)
1.
Block the measuring water
2.
Separate the electrode cabl
able from the controller
3.
Unscrew the redox electrod
rode from the measurement chamber
4.
Rinse the redox electrode o
e off with (distilled) water
5.
Carefully dab the redox elec
lectrode dry using a cloth (free from
grease and fluff)
6.
Connect the electrode cable
ble to the controller again.
7.
In the menu, select the func
unction 8
8.
Enter the buffer solution's re
s redox value as the
(e.g. 465 mV)
9.
Dip the redox electrode into
nto the buffer solution (e.g. 465 mV)
and stir it carefully and brief
riefly.
10.
If the measured value displa
splayed has stabilised and is no longer
changing in a relevant mann
anner, then confirm calibration by
pressing ( 9
11.
Check the calibration results
ults displayed and close calibration by
pressing > '$
12.
Place the redox electrode b
e back into the measurement chamber
13.
Open the shut'off valves for
for the measuring water
13.4.2
Calibration errors
During calibration, various plausib
sibility criteria are checked. If one of the
criteria is not met, then a corresp
esponding error message appears and
calibration is not executed.
The following criteria have to be m
e met for successful calibration:
•
The offset calculated (zero p
o point shift) has to be in the range of
±100 mV. The offset is g
s generally close to 0 for flawless
electrodes.
13.5
Determining the redo
dox (mV) setpoint
Electrode calibration is not of de
decisive importance for redox control.
Correct determination of the redox
dox setpoint is.
After all, redox control should pro
provide the desired level of chlorine /
bromine in the pool. As long a
as water quality and other general
conditions do not change signific
ificantly, the redox value measured is
directly dependent upon the conce
ncentration of free chlorine / bromine. A
change in chlorine / bromine conc
oncentration always results in a change
in the redox potential measured
red. Conversely, this means that the
chlorine / bromine concentration re
n remains constant if the control system
is providing a constant redox va
value. It counteracts a sinking redox
value immediately by dosing chlor
hlorine / bromine, thereby maintaining a
constant redox value at the config
figured setpoint.
IMPORTANT NOTI
TICE!
Determining the c
e correct redox setpoint
The redox value f
e for the desired chlorine / bromine
value can vary wide
idely from pool to pool.
Therefore, the c
correct redox setpoint must be
determined individ
ividually for each pool.
Values experienced
ced in the past are surely helpful for
orientation. Howev
ever, the redox setpoint cannot be
configured based s
d solely on values experienced in the
past, as the correct
ect redox setpoint in an individual case
can deviate signific
ificantly from values experiences in the
past.
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> ' 9 * .,
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