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12
Calibration (basic measurement comparison)
12.4.1.2 Calibration results
At the end of calibration, the calibration parameters generated are
displayed:
Offset
Offset is the zero point displacement calculated from calibration. It is
indicated in [mV].
Current measured value
The redox (mV) measured value is then calculated using the
parameters from the current calibration. The measured value
displayed should therefore coincide with the calibration value entered.
12.4.1.3 Step by step
1-point calibration with buffer solution (e.g. 465 mV)
31.
Block the measurement water
32.
Separate the electrode cable from the device
33.
Unscrew the redox electrode from the measurement chamber
34.
Rinse the redox electrode off with (distilled) water
35.
Carefully dab the redox electrode dry using a towel (free from
grease and fuzz)
36.
Connect the electrode cable to the device again.
37.
In the menu, select the function 1-point calibration Redox (mV)
38.
Enter the buffer solution's redox value as the calibration value
Redox (mV), e.g. 465 mV
39.
Dip the redox electrode into the buffer solution (e.g. 465 mV)
and stir it carefully
40.
If the measured value displayed has stablised and is no longer
changing in a relevant manner, then confirm calibration by
pressing Next.
41.
Check the calibration results displayed and close calibration by
pressing Ready.
42.
Place the redox electrode back into the measurement chamber
43.
Open the shut-off valves for the measurement water
12.4.2
Calibration errors
During calibration, various plausibility criteria are checked. If one of the
criteria is not met, then a corresponding error message appears and
calibration is not executed.
The following criteria have to be met for successful calibration:
The offset calculated (zero point displacement) has to be in the
•
range of ±100 mV. The offset is generally close to 0 for flawless
electrodes.
12.5
Determining the redox (mV) setpoint
Electrode calibration is not of decisive importance for redox control.
Correct determination of the redox setpoint is.
After all, redox control should provide a predefined chlorine/bromine
level. As long as water quality and other general conditions do not
change significantly, the redox value measured is directly dependent
upon the concentration of free chlorine/bromine. A change in
chlorine/bromine concentration always results in a change in the redox
potential measured. Conversely, this means that the chlorine/bromine
concentration remains constant if the control system is providing a
constant redox value. It counteracts a sinking redox value immediately
by dosing chlorine/bromine, thereby maintaining the redox value
consistently at the configured setpoint.
12.5.1
Step by step
1. Bring the pool to the desired value via manual dosage or manual
addition of chlorine or bromine. It's best to add the requisite
volume in multiple increments and to check the value repeatedly
using DPD measurements.
2. After the desired chlorine or bromine value has been set in the
pool and checked via DDP measurement, observe the redox
value shown on the PoolManager
It will rise due to the addition of chlorine or bromine.
3. Wait until the displayed value has stablised. It should stop
experiencing relevant changes within 10-15 minutes.
4. The redox value shown corresponds to the previously configured
chlorine/bromine value in the pool. Thus, configure the redox
value shown as the setpoint for redox control.
5. Redox control will then maintain the redox value at the configured
setpoint, simultaneously providing for a constant chlorine/bromine
value in the pool.
User Manual PoolManager
®
IMPORTANT NOTICE!
Determining the correct redox setpoint
The redox value configured for the desired
chlorine/bromine value can vary widely from pool to
pool.
Therefore, the correct redox setpoint must be
determined individually for each pool.
Values experienced in the past are surely helpful for
evaluation. However, the redox setpoint cannot be
configured based solely on values experienced in the
past, as the correct redox setpoint in an individual case
can deviate significantly from values experiences in the
past.
®
.
IMPORTANT NOTICE!
Redox electrode stablisation
Depending on water quality and the state of the
electrode, it can occur that the redox electrode reacts
very slowly when reinserted or when moved from the
buffer solution back into the measurement water after
calibration. In disadvantageous conditions, it may take
up to 24 hours for the measured redox value to stablise
and be displayed correctly.
The correct redox value cannot be read and applied as
the setpoint until after stablisation has occurred.
Recommendations:
Insert a new redox electrode into the measurement
water circuit as early as possible. Then, it will be able to
stablise even if the final chlorine/bromine value is not
yet configured.
Observe the redox value for at least 15 minutes. The
redox value cannot be considered to be sufficiently
stable until the change over that time frame is max. 1-
2 mV.
Even if the value no longer changes within 15 minutes,
under certain circumstances it may slowly rise up to 20
or 30 mV over the next 24 hours. Therefore, check
redox control again a few days after launching. Perform
a DPD measurement and optimise the configured
redox setpoint as needed.
37
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