wtw inoLab 740, Operating Manual, Page: 240 / 274

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