Hanna Instruments HI 903 - Manual (Page 124)

8-8
MAINTENANCE, PERIPHERALS
8.3 Peripherals
Warning! Connection/disconnection of POWER CORD, PUMP ASSEMBLY, EXTERNAL PC
DISPLAY, PRINTER, RS232 INTERFACE or EXPANSION DEVICE must be done
only when titrator and external devices are turned off.
8.2 Probe Maintenance
Proper probe maintenance is crucial for reliable measurements and extending the life
of the probe. The frequency of maintenance will depend largely on the type of samples
that are analyzed. Maintenance may be required if any of the following are observed:
• Slow or no electrode response;
• Noisy mV readings;
• Debris on or between electrode pins
• Coating on electrode pins
If these signs are observed, the electrode pins may be dirty. Rinse the electrode with
a solvent that is appropriate for the type of sample used – methanol is usually sufficient.
Allow the probe to dry completely before re-installing.
If a more thorough cleaning is required, soak the electrode in HI 7061 Electrode
Cleaning Solution for General Use for several hours, then rinse with water followed by
methanol. Allow to dry before re-installing.
After allowing the probe to dry, inspect the glass cracks, especially near the electrode
pins. Replace the electrode if any cracks are found.
Warning: Take care to protect the electrode pins from damage! Avoid using brushes/
abrasives to clean the pins. Pins can easily bend, which will cause permanent
errors in mV readings!