Endress+Hauser Liquisys M CCM223 - Page 90

Diagnostics and troubleshooting Liquisys M CCM223/253
90 Endress+Hauser
Error Possible cause Tests/remedial action Tools, spare parts
Shunt in chlorine sensor Replace sensor Replacement sensor
Chlorine value too
low
Measuring chamber not
closed
Refill and screw closed carefully Electrolyte
Air cushion outside in
front of membrane
Remove air bubble, possibly
select better installation
position
Air cushion inside
membrane
Refill and screw closed so that it
is bubble-free
Electrolyte
Chlorine value
wrong/cannot be
calibrated; zero
current too large
Wrong polarization
voltage
Measure polarization voltage,
replace MKC1 module if
necessary.
DVM (+) at S or 90, DVM
(-) at 91
CCS140/141: -20 mV
CCS240/241: +120 mV
Wrong sensor type
selected
Check sensor selection
pH/mV
measurement:
Measuring chain
zero-point cannot
be adjusted
Contaminated reference
system
Test with new sensor pH/mV sensor
Membrane clogged Clean or grind membranes (not
with TEFLON® membranes)
HCl 3%, needle file (only
file in one direction); new
sensor
Measuring line open Short-circuit pH input and
connect to PM -> reading pH 7
Asymmetric sensor
voltage too high
Clean junction or test with
another sensor
HCl 3%, needle file (only
file in one direction); new
sensor
Potential matching of
Liquisys -> medium
incorrect
Always connect CCM223/253
symmetrically with PM.
Wiring diagrams
No or slow change
of readings
Sensor fouled Clean sensor Cleaning agent
Sensor old Replace sensor New sensor
Sensor defective
(reference lead)
Replace sensor New sensor
Measuring chain
slope not
adjustable/
slope too low
Connection not at high
impedance
(moisture, dirt)
Check cable, plug connector and
junction boxes
pH simulator, insulation
tester
Device input defective pH measurement directly at
device
pH simulator
Sensor old Replace sensor pH sensor
Measuring chain
slope not
adjustable/
No slope
Hair-line crack in the glass
membrane
Replace sensor pH sensor
Connection not at high
impedance
Check cable, plug connector and
junction boxes
pH simulator, insulation
tester
Constant, incorrect
measured value
Sensor does not immerse
properly or protection cap
not removed
Check installation position,
remove protection cap
Air pockets in assembly Check assembly and installation
position
Grounding short at or in
device
Perform test measurement in
insulated vessel, perform with
buffer solution if required.
Plastic vessel, buffer
solutions
Hair-line crack in the glass
membrane
Replace sensor pH sensor