wtw inoLab Level 3 Operating Manual page 240

What to do if...
No stable
measured value
240
Cause
Measuring system:
– Incorrect calibration
procedure
– Incorrect solution
temperature
(without temperature
probe)
– Socket damp
Buffer solutions
– Incorrect buffer solutions
– Buffer solutions too old
– Buffer solutions depleted
Cause
pH/ORP electrode:
– Diaphragm contaminated
– Membrane contaminated
Test sample:
– pH value not stable
– Temperature not stable
Remedy
– Select correct procedure
– Set up correct
temperature
– Dry socket
– Change calibration
procedure
– Use only once.
Note the shelf life
– Change solutions
Remedy
– Clean diaphragm
– Clean membrane
– Measure with air
excluded if necessary
– Adjust temperature if
necessary