Hach-Lange NO3D sc Nitrate Sensor - Manual (Page 34)

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Troubleshooting
6.3 Troubleshooting
6.3.1 Troubleshooting during operation
Symptom Possible cause Corrective actions
Incorrect measurement
values
Calibration too old; calibration was not suitable for
the particular case; big change in the waste water
matrix
Carry out suitable calibration
See
4.6 Calibration on page 22
Strongly contaminated membranes and/or
reference electrode
Clean the sensor cartridge using a brush
and/or rinse the sensor cartridge with clean
water (without cleaning agents), and wipe the
sensor cartridge carefully with a soft, clean
cloth.
Clean all components (membranes/reference
electrode/temperature sensor).
Install cleaning unit
Increase cleaning interval
Sensor membrane damaged
Check sensor installation/replace sensor
cartridge
Reference element damaged
Check sensor installation/replace sensor
cartridge
NO3 mV RANGE! (Nitrate mV value is out of
measuring range)
Replace sensor cartridge
CL- mV RANGE! (Chloride mV value is out of
measuring range)
Replace sensor cartridge
pHD RANGE! (pHD reference value is out of
range)
Replace sensor cartridge
TEMPERATURE (temperature value is out of
range) Replace sensor cartridge/check waste water
temperature
CARTRIDGE OLD (cartridge more than 1 year
old)
Replace sensor cartridge
Dampness at the contacts of the sensor cartridge
Dry the contacts with a cloth or some paper.
Check the opaque gasket for damage and
the correct position.
Screw the locking ring on.
Note: Use the cap of the storage container as
a tool/screwing aid for the locking ring
(
Figure 9 on page 15 ).