Hanna Instruments BL 7916 - Manual (Page 15)

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• Slow Response/Excessive Drift: Soak the tip in Hanna Solu-
tion HI 7061 for 30 minutes, rinse thoroughly in distilled water
and then follow the Cleaning Procedure above.
• For ORP Electrodes: polish the metal tip with a lightly
abrasive paper (paying attention not to scratch the surface) and
wash thoroughly with water.
Note: with industrial applications, it is always recommended to keep
at least one spare electrode handy. When anomalies are not
resolved with a simple maintenance, change the electrode
(and recalibrate the controller) to see if the problem is
alleviated.
For refillable electrodes**:
Refill the electrode with fresh electrolyte (HI 7071 for single junction or
HI 7082 for double junction electrodes). Allow the electrode to stand
upright for 1 hour. Follow the Storage Procedure above.
CLEANING PROCEDURE
General Soak in HI 7061 general cleaning solution for
approximately 30 minutes.
Removal of films, dirt or deposits on the membrane/junction:
Protein
Soak in HI 7073 protein cleaning solution for 15
minutes.
Inorganic Soak in HI 7074 inorganic cleaning solution for
15 minutes.
Oil /grease Rinse with HI 7077 Oil & Fat cleaning solution.
IMPORTANT: After performing any of the cleaning procedures rinse
the electrode thoroughly with distilled water, drain and refill the
reference chamber with fresh electrolyte (not necessary for gel-filled
electrodes), and soak the electrode in HI 70300 storage solution for at
least 1 hour before reinstalling it.
TROUBLESHOOTING
Evaluate your electrode performance based on the following.
• Noise (Readings fluctuate up and down) could be due to:
- Clogged/Dirty Junction: Refer to the Cleaning Procedure
above.
- Loss of shielding due to low electrolyte level (refillable
electrodes only): refill with HI 7071 for single junction or HI
7082 for double junction electrodes.
• Dry Membrane/Junction: Soak in HI 70300 storage solution for
at least 1 hour. Check to make sure the installation is such as to
create a well for the electrode bulb to constantly remain moist.
• Drifting: Soak the electrode tip in warm HI 7082 solution for
one hour and rinse tip with distilled water (if necessary, refill with
fresh HI 7071 for single junction electrodes and HI 7082 for
double junction electrodes).
• Low Slope: Refer to the cleaning procedure above.
• No Slope: - Check the electrode for cracks in glass stem or
bulb (replace the electrode if cracks are found).
- Make sure cable and connections are not dam-
aged nor lying in a pool of water or solution.
**For industrial applications, gel-filled electrodes are preferable due to lesser maintenance requirements.