Hanna Instruments HI 84430 - Manual (Page 18)

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Press LOG to memorize the current reading. A message indicating the free log space will be
displayed for a few seconds.
In order to take pH measurements follow the next steps:
• Submerge the pH bulb 2 cm (0,8’’) and the temperature probe into the sample to be tested
and stir gently. Allow time for the electrode to stabilize. When the reading becomes stable the
(unstable measurement) symbol will disappear.
• If the pH reading is less then -2.00 pH or greater then 16.00 pH the closest full-scale value
(-2.00 pH or 16.00 pH) will be displayed blinking.
If measurements are taken successively in different samples, it is recommended to rinse the
electrodes thoroughly with deionized water or distilled water and then with some of the next
sample to prevent cross-contamination.
The pH measurement is affected by temperature. In order to have accurate pH measurements, the
temperature effect must be compensated for. To use the Automatic Temperature Compensation
(ATC) feature, connect and submerge the HI 7662-M temperature probe into the sample in the
dedicated tubeguide and wait for a few seconds. The “ATC” message will be shown on the
display. Automatic Temperature Compensation will provide pH corrected values at the temperature
of measurements. If Manual Temperature Compensation (MTC) is desired, the temperature probe
must be disconnected from the instrument. The default temperature of 25 °C (77 °F) or the last
temperature reading will be displayed preceded by the symbol and the “MTC” message.
The manually set temperature can now be adjusted with the ARROW keys (from -20.0 to 120.0 °C).
pH MEASUREMENT
The HI 84430 may be used as a pH meter for direct measurements.
Verify that the instrument has been calibrated before taking pH measurements. Set the instrument
to pH meter. At power up the instrument enters pH meter mode. From titrator mode press ESC
until pH units are displayed.
If an electrode calibration hasn’t been performed, or the number of days exceedes calibration time
out value set, the message “CAL DUE” will blink on the left side of the display (see Calibration
timeout option in Setup for details).
If CAL DUE is displayed perform an electrode calibration.
Place calibrated pH electrode into electrode holder. Open the fill hole.
Rinse the pH tip with distilled or deionized water. Immerse the pH electrode (bottom 2 cm / 0.8”)
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 a few drops of the solution to be tested, before taking measurements. Press LOG to record
sample pH in instrument pH log.
Press MENU to access the instrument’s menu.
Press HELP to view the contextual help, every time you need supplementary information. The help
is customized for every situation that can appear during instrument usage.
Press STIR to start/stop the stirrer.
Press Titrator to enter titrator mode.
Press CAL to access the calibration menu.
The pump GLP displays the Time and Date of the last pump calibration.
If a calibration hasn’t been performed the message “Not Calibrated” will be displayed.