Electrode Conditioning And Maintenance - Hanna Instruments pH 21 Instruction Manual

• Wait till the hourglass symbol on the LCD turns off and the "pH"
tag stops blinking, then press CFM to confirm the second calibra-
tion point (slope).
• The meter automatically returns to normal measurement mode.
Note: To abort a calibration procedure and save previous calibration
data, press the CAL key while the "pH" tag is still blinking.
Recommendations for Users
Before using these products, make sure that they are entirely suitable for the environ-
ment in which they are used.
Operation of these instruments in residential area could cause unacceptable inter-
ferences to radio and TV equipments, requiring the operator to take all necessary
steps to correct interferences.
The glass bulb at the end of the electrode is sensitive to electrostatic discharges.
Avoid touching this glass bulb at all times.
During operation, ESD wrist straps should be worn to avoid possible damage to the
electrode by electrostatic discharges.
Any variation introduced by the user to the supplied equipment may degrade the
instrument's EMC performance.
To avoid electrical shock, do not use these instruments when voltages at the measure-
ment surface exceed 24VAC or 60VDC.
To avoid damages or burns, do not perform any measurement in microwave ovens.
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ELECTRODE CONDITIONING & MAINTENANCE
PREPARATION
Remove the electrode protective cap.
DO NOT BE ALARMED IF ANY SALT DEPOSITS ARE PRESENT: this is
normal with electrodes and they will disappear when rinsed with
water.
During transport tiny bubbles of air may have formed inside the glass
bulb. The electrode cannot function properly under these conditions.
These bubbles can be removed by "shaking down" the electrode as
you would do with a glass thermometer.
If the bulb and/or junction are dry, soak the electrode in HI 70300
Storage Solution for at least one hour.
For refillable electrodes, if the refill solution (electrolyte) is more than
2½ cm (1") below the fill hole, add the appropriate Electrolyte
Solution.
MEASUREMENT
Rinse the electrode tip with distilled water, immerse it (4 cm / 1½")
in the sample and stir gently for a few seconds.
For a faster response and to avoid cross contamination of the samples,
rinse the electrode tip with the solution to be tested, before taking
any measurements.
STORAGE
To minimize clogging and ensure a quick response time, the glass
bulb and the junction should always be kept moist.
When not in use, store it with a few drops of HI 70300 storage
solution or HI 7007 pH 7.01 buffer in the protective cap.
NEVER STORE THE ELECTRODE IN DISTILLED OR DEIONIZED
WATER.
PERIODIC MAINTENANCE
Inspect electrode and cable. The cable used for the connection to the
meter must be intact and there must be no points of broken
insulation on the cable or cracks on the electrode stem or bulb. If any
scratches or cracks are present, replace the electrode. Rinse off any salt
deposits with water.
Connectors must be perfectly clean and dry.
Refill the electrode with fresh electrolyte (see the electrode's specifica-
tions to select the correct refilling solution). Allow the electrode to
stand upright for 1 hour. Follow the Storage Procedure.
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