Pr
o
Minent
®
Page 64
Sensor:
Troubleshooting
Chlorine Dioxide Sensor CDP
Fault
The sensor cannot be
calibrated - meter/
controller display value
is
greater
than DPD-1
measurement
The sensor cannot be
calibrated - meter/
controller display value
is smaller than DPD-1
measurement
Measuring value
readout is “Zero”
Measuring value
readout unstable
Possible cause
Run-in period too short
Diaphragm cap damaged
Interference from water
con tam inant
Short circuit in signal cable
DPD chemicals spent
Run-in period too short
Diaphragm cap deposits
Sample water fl ow inadequate
Air bubbles on the outside of the
diaphragm
Reference electrode spent (shiny
patches showing)
Surfactant in water (diaphragm is
translucent)
No electrolyte in diaphragm cap
Electrolyte is penetrating sample
water via gas bubbles
Interference from water
con tam inant
ClO
2
content below the lower
measuring range limit
Sensor incorrectly connected to
controller
Air bubbles on the outside of the
diaphragm
Diaphragm damaged
Cause lies with the controller
Remedy
See “Run-in Period”
Replace diaphragm cap. Run-in
sensor, calibrate
Identify interfering contaminant
and implement remedy
Identify short circuit and repair
Use new DPD chemicals, repeat
calibration
See “Run-in Period”
Remove deposits (see “Main te-
nance”). Replace diaphragm
cap. Run-in sensor, calibrate
Correct the fl ow
Tap to remove air bubbles and
increase fl ow if necessary
Return sensor
Remove surfactant and replace
diaphragm cap, Run-in sensor,
calibrate; use CDP sensor
Add new electrolyte (see
“Assembly”, “Run-in Period”
and “Calibration”)
Discuss with ProMinent
Identify interfering contaminant
and if necessary replace water
Add ClO
2
and then repeat
calibration or use appropriate
sensor
Connect sensor correctly to
controller
Tap to remove air bubbles and
increase fl ow if neccessary
Replace diaphragm cap, Run-in
sensor, calibrate
Identify cause and remedy
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24.02.2009 11:56:07 Uhr
24.02.2009 11:56:07 Uhr