Fault Finding - Grundfos AQC-D13 Montage- Und Betriebsanleitung

11.5 Fault finding

Caution
Observe the installation and operating instructions of the measuring amplifier and controller!
Fault
1. No display. No electricity
supply to the measuring
cell.
2. The measured value is
lower than the reference
measurement.
3. The measured value is
higher than the reference
measurement.
4. The measured value is
unstable.
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Cause
a) A disinfection or oxidation agent is missing in the
sample water.
b) The electrode cable connection is interrupted.
c) No or too low sample water flow rate.
d) The measuring electrode is faulty.
e) The measuring electrode is contaminated or made
passive by deposits.
a) The measuring electrode is faulty.
b) The measuring electrode is contaminated or made
passive by deposits.
c) The temperature has fallen since the calibration.
d) The system has run too short time prior to
calibration.
e) Unsuitable chlorination agent.
f) Incorrect reference measurement during
calibration.
g) The pH value for the chlorine measurement has
risen since the calibration.
h) The quantity of sample water is set too low.
i) The cleaning wing is blocked.
a) The temperature has risen since the calibration.
b) The pH value for the chlorine measurement has
fallen since the calibration.
c) Interference by other oxidation agents in the
sample water.
a) Interferences on the signal lines.
b) The reference electrode diaphragm is blocked.
c) The measuring electrode is contaminated or faulty. Clean the measuring electrode using a diluted
d) The filter is contaminated, and the quantity of
sample water is therefore too low.
e) Siphon effect at the sample water outlet.
Remedy
Check the concentration by making a reference
measurement. Check the dosing units, and
activate dosing. Check the settings of the
measuring amplifier.
Remake the connection. Replace damaged
cables.
Clean the filter, check the flow rate, and check
the sample water inlet pressure.
Replace the measuring electrode.
Dismantle, clean or replace the measuring
electrode.
Replace the measuring electrode.
Remove, clean or replace the measuring
electrode.
Activate the automatic temperature
compensation, if applicable. Recalibrate.
Let the system run for at least two hours.
Recalibrate.
Only use chlorine solutions such as chloric gas,
sodium hypochlorite and chlorinated lime.
Do not use organic products such as
trichloroisocyanuric acid.
Check the reference measurement, and take
another measurement. Recalibrate.
Keep the pH value constant. Activate the pH
value compensation, if applicable. Recalibrate.
Check and set the quantity of sample water.
Check the filter, and clean it, if necessary.
Fit the cleaning wing correctly.
Activate the automatic temperature
compensation, if applicable. Recalibrate.
Keep the pH value constant. Activate the pH
value compensation, if applicable. Recalibrate.
Analyse the sample water. Check the chemicals
used.
Check the screen and the connections to the
amplifier.
Clean the diaphragm (on the side at the bottom
of the reference electrode) using diluted
hydrochloric acid (10 %). Replace the reference
electrode, if necessary.
abrasive cleaning agent. Replace the measuring
electrode, if necessary.
Check the filter, and clean it, if necessary.
Ensure a flow of sample water with no
counterpressure.