ProMinent DULCOTEST CLB1-mA-10ppm Guide De Montage Et De Service page 44

Troubleshooting
7 Troubleshooting
Fault
Sensor cannot be cali‐
brated – display on meas‐
uring device / controller
higher than DPD-1 meas‐
urement
Sensor cannot be cali‐
brated – display on meas‐
uring device / controller
lower than DPD-1 meas‐
urement
44
Possible cause
Run-in time too short
Membrane cap damaged
Troublesome substances in the water
Short circuit in the measuring line
DPD chemicals out of date
pH value < pH 5.5
Run-in time too short
Coating on the membrane cap
Sample water flow rate too low
Air bubbles on the outside of the mem‐
brane
Remedy
Refer to """Run-in time"""
Ä Table on page 42
Replace membrane cap;
allow sensor to run in,
calibrate
Check water for trouble‐
some substances and
remedy this
Identify short circuit and
eliminate the cause
User new chemicals,
repeat calibration
Increase pH value (pH
5.5-8.0)
Refer to """Run-in time"""
Ä Table on page 42
Remove coating - refer to
"""Maintenance""",
replace membrane cap;
allow sensor to run in,
calibrate
Correct flow rate
Remove air bubbles by
tapping and increase flow
rate if necessary