Liquisys M CPM223/253
Trouble-shooting
Hauser
89
9.3
Process specific errors
Use the following table to localise and rectify any errors occurring.
Errors
Possible cause
Tests and/or remedial measures
Tools, spare parts
Device cannot be operated,
display value 9999
Operation locked
Press CAL and MINUS keys simultaneously
See "Function of keys" section.
Measuring chain zero-point
cannot be adjusted
Reference system toxified
Test with new sensor
pH/redox sensor
Diaphragm clogged
Clean or grind down diaphragm
HCl 3 %, use file (only file in one direction)
Measuring line open
Short-circuit pH input on instrument
⇒
display pH 7
Sensor asymmetry voltage too high
Clean diaphragm or test with another
sensor
HCl 3 %, use file (only file in one direction);
sensor
Potential matching (PA/PM)
transmitter
⇔
wrong medium
Asymm.: no PM or PM at PE
Symm.: PM connection mandatory
See "Electrode installation and measuring
cable connection" section
No or creeping change of
display
Sensor contaminated
Clean sensor.
See "Cleaning pH/redox electrodes" section.
Sensor ageing
Replace sensor.
New sensor
Sensor defective (reference lead)
Replace sensor.
New sensor
No internal buffer
Check KCl supply (0.8 bar (11.6 psi) above
medium pressure).
KCl (CPY 4-x)
Measuring chain slope not
adjustable/slope too small
No high-impedance connection
(moisture, dirt)
Check cable, plug connector and junction
boxes.
pH simulator, insulation, see "Checking the
connecting lines and boxes" section
Device input defective
Check device directly.
pH simulator
Sensor ageing
Renew sensor.
pH sensor
Measuring chain slope not
adjustable/no slope
Hair-line crack in the glass membrane
Renew sensor.
pH sensor
No high-impedance connection
(moisture, dirt)
Check cable, plug connector and junction
boxes.
pH simulator, insulation, see "Checking the
connecting lines and boxes" section
Permanent, incorrect
measured value
Sensor not immersing or protection cap
not removed
Check installation position, remove
protection cap.
Air cushion in assembly
Check assembly and orientation.
Ground connection at or in device
Perform test measurement in insulated
vessel, poss. with buffer solution.
Plastic vessel, buffer solutions
Hair-line crack in the glass membrane
Renew sensor.
pH sensor
Impermissible device operating status
(no reaction to key actuation)
Switch device off and then on again.
EMC problem: if this persists, check the
grounding, screens and line routing or have
checked by Hauser Service.
Incorrect temperature value
Incorrect sensor connection
Check connections using wiring diagram.
Wiring diagram "Electrical connection"
section
Measuring cable defective
Check cables for
interruptions/short-circuit/shunt.
Ohmmeter
Incorrect sensor type
Set type of temperature sensor at the device
(field B1).
Glass electrode: Pt 100
ISFET: Pt 1000
pH value in process wrong
No/incorrect temperature
compensation
ATC: activate function.
MTC: adjust process temperature.
Conductivity of medium too low
Select pH sensor with liquid KCl.
e.g. Ceraliquid CPS41
Flow too high
Reduce flow or measure in a bypass.
Potential in medium
Poss. ground with or at PM pin (connection
PM/PE).
Problem occurs particularly in plastic lines.
Sensor contaminated or assigned
Clean sensor (see "Cleaning pH/redox
sensors" section).
For heavily contaminated media:
Use spray cleaning.
