Hanna Instruments edge PHM4092, Руководство пользователя, Страница: 37 / 44

Maintenance 37
Replace the solution in the protective cap with a few drops of HI 70300 or
HI 80300 Storage Solution or, in its absence, Filling Solution (HI 7082 or
HI 8082 for double junction electrodes).
Follow the preparation procedure before taking measurements.
Note : NEVER STORE THE ELECTRODE IN DISTILLED OR DEIONIZED WATER.
Periodic Maintenance
Inspect the electrode and the cable. The cable used for connection to the
instrument must be intact and there must be no points of broken insulation on
the cable or cracks on the electrode stem or bulb. Connectors must be perfectly
clean and dry. If any scratches or cracks are present, replace the electrode. Rinse
off any salt deposits with water.
For refi llable electrodes: Refi ll the reference chamber with fresh electrolyte
(HI 7082 or HI 8082 for double junction electrodes). Allow the electrode to
stand upright for 1 hour.
Follow the Storage Procedure above.
Cleaning Procedure
Use diagnostic messages to aid pH electrode troubleshooting. Several cleaning
solutions are available:
• General – Soak in Hanna HI 7061 or HI 8061 General Cleaning Solution
for approximately ½ hour.
• Protein –Soak in Hanna HI 7073 or HI 8073 Protein Cleaning Solution
for 15 minutes.
• Inorganic – Soak in Hanna HI 7074 Inorganic Cleaning Solution for
15 minutes.
• Oil/grease – Rinse with Hanna HI 7077 or HI 8077 Oil and Fat Cleaning
Solution.
Note : After performing any of the cleaning procedures, rinse the electrode
thoroughly with distilled water, refi ll the reference chamber with fresh
electrolyte (not necessary for gel-fi lled electrodes) and soak the electrode
in HI 70300 or HI 80300 Storage Solution for at least 1 hour before taking
measurements.
Temperature Correlation For pH Sensitive Glass
Verify the temperature range by reading the limits on electrodes cap. The pH
electrode’s life also depends on the temperature that is used. If constantly cycled
between two temperatures, the life of the electrode is drastically reduced.
Alkaline Error
High concentrations of sodium ions interfere with readings in alkaline solutions.
The pH at which the interference starts to be signifi cant depends upon the
composition of the glass. This interference is called alkaline error and causes
the pH to be underestimated. Hanna’s glass formulations have the indicated
characteristics.
Sodium Ion error for various glass types at ambient temperature
Alkali Error with 0.1 mol/L Na +
pH GP HT LT
12.5 0.11 0.05 0.28
13.0 0.23 0.11 0.35
13.5 0.35 0.16 0.45
14.0 0.48 0.20 0.54
pH Probe
Maintenance