Instruction manual

TROUBLESHOOTING
Troubleshooting Guide
Following is a systematic procedure to isolate the problem.
The pH measuring systems can be divided into four components for
ease in troubleshooting: pH Meter, Electrodes, Sample/Application,
and Technique.
pH Meter
The meter is the component which is easiest to eliminate as a
possible cause of error. Orion pH meters are provided with an
instrument checkout procedure and shorting cap for convenience in
troubleshooting. Consult your pH meter instruction manual
for directions.
Electrodes
To test electrode operation:
1. Connect electrode to a working meter.
2. Set function switch to absolute mV mode.
3. Immerse electrode in fresh pH 7 buffer.
4. Displayed value should be 0 ± 30 mV.
5. Rinse electrode and immerse in fresh pH 4 buffer.
6. Displayed value should be approximately 160 - 180mV greater
than in step 4. (Actual mV values may change as electrode
ages but mV differences will remain 160 to 180 mV).
If the electrode fails this procedure, clean thoroughly as directed in
Maintenance.
If electrode response is slow or drifting, drain and refill with fresh
ROSS
™
Internal Filling Solution, Orion 810007. See Measuring
Hints.
If cleaning and maintenance fail to rejuvenate the electrode:
1. For separate pH and reference half cells, substitute each
electrode (one at a time) with a known working electrode and
repeat test procedure. By process of elimination, determine
which electrode should be replaced.
2. For combination pH electrodes, replace the entire electrode.
Sample/Application
The electrode and meter may operate with buffers but not with your
sample. In this case, check sample composition for interferences,
incompatibilities, or temperature effects.
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