Troubleshooting
8
Fault
Possible cause
The sensor
Run-in period too short
cannot be
Membrane cap damaged
calibrated -
measuring
Interference from water
device/
contaminants (see 15 Technical
controller
data, "Cross-sensitivity")
display value is
Short circuit in signal cable
greater than
DPD-1
DPD-chemicals spent
measurement
pH-value < pH 5.5
Run-in period too short
The sensor
cannot be
Membrane cap deposits
calibrated -
measuring
device/
Sample water flow inadequate
controller
display value is
Air bubbles on the outside of the
smaller than
membrane
DPD-1
Surfactants in water (membrane is
measurement
transparent!)
pH-value > pH 8.0
No electrolyte in membrane cap
Electrolyte displaced by gas
bubbles in the sample water
Only bound chlorine present
Measured
variable value
is "zero"
Chlorine content below the lower
measuring range limit
Sensor incorrectly connected to
controller
Run-in period inadequate
Sensor defective
Measured
Air bubbles on the outside of the
variable display
membrane
unstable
Membrane damaged
Cause lies with the controller
26
Troubleshooting
Remedy
See 7.1 "Run-in period"
Replace membrane cap.
Allow sensor to run in, calibrate
Identify interfering contaminant and
implement remedy
Identify short circuit and repair
Use new DPD chemicals, repeat
calibration
Increase pH-value (pH 5.5-8.0)
See 7.1 "Run-in period"
Remove deposits (see 9
"Maintenance"). Replace membrane
cap. Run-in sensor, calibrate
Increase flow (see 15 "Technical
data")
Tap to remove air bubbles and in
crease flow if necessary
Remove surfactants and replace
membrane cap, run in sensor and
recalibrate. If nec. use CDP sensor
Lower pH-value (pH 5.5-8.0)
Add new electrolyte (see 5
"Assembly", section 7.1 "Run-in
period" and section 7.2 "Calibration")
Consult ProMinent
If chloramine is present (DPD-4 test),
replace water or chlorinate
Add chlorine and then repeat
calibration or use appropriate sensor
Connect sensor correctly to
controller
Run in for at least 3 h
Replace sensor
Tap to remove air bubbles and
increase flow if necessary
Replace membrane cap. Run-in
sensor, calibrate
Identify cause and remedy
ProMinent
®