Pr
o
Minent
®
26
Fault
The sensor
cannot be
calibrated -
measuring
device/
controller
display value is
greater
than
DPD-1
measurement
The sensor
cannot be
calibrated -
measuring
device/
controller
display value is
smaller
than
DPD-1
measurement
Measured
variable value
is “zero”
Measured
variable display
unstable
Remedy
왘
See 7.1 “Run-in period”
왘
Replace membrane cap.
Allow sensor to run in, calibrate
왘
Identify interfering contaminant and
implement remedy
왘
Identify short circuit and repair
왘
Use new DPD chemicals, repeat
calibration
왘
Increase pH-value (pH 5.5-8.0)
왘
See 7.1 “Run-in period”
왘
Remove deposits (see 9
“Maintenance”). Replace membrane
cap. Run-in sensor, calibrate
왘
Increase flow (see 15 “Technical
data”)
왘
Tap to remove air bubbles and in
crease flow if necessary
왘
Remove surfactants and replace
membrane cap, run in sensor and
recalibrate. If nec. use CDP sensor
왘
Lower pH-value (pH 5.5-8.0)
왘
Add new electrolyte (see 5
“Assembly”, section 7.1 “Run-in
period” and section 7.2 “Calibration”)
왘
Consult ProMinent
왘
If chloramine is present (DPD-4 test),
replace water or chlorinate
왘
Add chlorine and then repeat
calibration or use appropriate sensor
왘
Connect sensor correctly to
controller
왘
Run in for at least 3 h
왘
Replace sensor
왘
Tap to remove air bubbles and
increase flow if necessary
왘
Replace membrane cap. Run-in
sensor, calibrate
왘
Identify cause and remedy
Possible cause
Run-in period too short
Membrane cap damaged
Interference from water
contaminants (see 15 Technical
data, “Cross-sensitivity”)
Short circuit in signal cable
DPD-
chemicals spent
pH-
value < pH 5.5
Run-in period too short
Membrane cap deposits
Sample water flow inadequate
Air bubbles on the outside of the
membrane
Surfactants in water (membrane is
transparent!)
pH-value > pH 8.0
No electrolyte in membrane cap
Electrolyte displaced by gas
bubbles in the sample water
Only bound chlorine present
Chlorine content below the lower
measuring range limit
Sensor incorrectly connected to
controller
Run-in period inadequate
Sensor defective
Air bubbles on the outside of the
membrane
Membrane damaged
Cause lies with the controller
8
Troubleshooting
Troubleshooting
BA_DT_123_04_12_4spr.p65
20.04.2012, 7:08 Uhr
26
