Endress+Hauser Liquisys M CCM223, Operating Instructions Manual

Page: 80 / 124

Diagnostics and troubleshooting Liquisys M CCM223/253
80 Hauser
Chlorine value too low
Measuring chamber not closed Refill and carefully screw tight. Electrolyte CCY14-F or CCY24-F
Air cushion outside in front of
membrane
Remove air bubble, possibly choose
better installation position.
Air cushion under membrane Refill and carefully screw tight bubble-
free. Electrolyte CCY14-F or CCY24-F
Chlorine value wrong / no
calibration possible; zero
current too large
Wrong polarisation voltage Measure polarisation voltage, replace
MKC1 module if required. 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 not adjustable
Reference system poisoned Test with new sensor. pH/mV sensor
Membrane blocked Clean / grind membranes (not with
TEFLON membranes).
HCl 3%, warding file (only file in one
direction); new sensor
Measuring line broken Short-circuit pH input and connect to PM
-> reading pH 7.
Asymmetrical voltage of sensor too
high Clean membranes or test with different
sensor. HCl 3%, file (only file in one direction);
new sensor.
Potential matching (PM) of Liquisys
M -> medium incorrect
CCM223/253 always connect
symmetrically to PM!
Connection diagram
No or slow change of
readings
Sensor dirty Clean sensor. Cleaning agent
Sensor aged Replace sensor. New sensor
Sensor defective (reference outgoing
lead)
Replace sensor. New sensor
Measuring chain slope
not adjustable /
Slope too low
Connection not at high impedance
(humidity, dirt) Test cable, connector and junction boxes. pH simulator, insulation tester
Instrument input defective pH measurement directly on the
instrument. pH simulator
Sensor aged Replace sensor. pH sensor
Measuring chain slope
not adjustable /
No slope
Hairline crack in glass membrane Replace sensor. pH sensor.
Connection not at high impedance Test cable, connector and junction boxes. pH simulator, insulation tester
Permanent, incorrect
reading
Sensor not immersed or protective
cap not removed Check installation position, remove
protective cap.
Air cushion in assembly Check assembly and installation
position.
Ground fault at or in the instrument Test measurement in insulated vessel,
possibly with buffer solution.
Plastic vessel, buffer solutions
Hairline crack in glass membrane Replace sensor. pH sensor
Instrument in impermissible
operating state (no response to key
actuation)
Switch instrument off and on. Possibly EMC problem: If repeated, check
grounding and wire routing
Incorrect temperature
reading Incorrect sensor connection Check connections. Connection diagrams
Sensor or measuring cable defective Test sensor and cable. Ohmmeter
pH value in process
incorrect
Flow rate too high Reduce flow rate or measure in a bypass.
Potential in medium Possibly ground with / at PM pin
(connect PA/PM to PE). Problem mainly occurs in plastic lines
Sensor covered in dirt or deposits Clean sensor. For highly polluted media: Use spray
cleaning
Error Possible cause Tests and / or remedial measures Equipment, spare parts, personnel