Hanna Instruments HI 84432 - Manual (Page 17)

17
ELECTRODE CALIBRATION PROCEDURE
It is recommended to calibrate the instrument frequently, especially if high accuracy is required.
The pH electrode should be recalibrated:
a) Whenever the pH electrode is replaced
b) At least once a week, but daily is advised
c) After electrode is cleaned
d) When high accuracy is required
e) If the pH calibration expired warning is displayed during measurement. Every time you clean
the electrode calibrate the instrument (see the “pH Cleaning Procedure” section) and use fresh buffers.
PROCEDURE
A single, two or three-points calibration can be performed, using the three predefined buffers
4.01, 7.01 and 8.20 pH. For a single point calibration any of the three buffers may be used,
but using 8.20 pH is recommended.
Note: The HI 84432 will not accept other pH buffers for calibration.
• Pour small quantities of selected buffer solutions into clean beakers. For accurate calibration
use two beakers for each buffer solution, the first one for rinsing the electrode and the second
one for calibration.
• Put a magnetic stir bar in each beaker with the calibration buffer solution.
• Remove the protective cap, open the fill hole and rinse the electrodes with some of the buffer
solution to be used for the first calibration point.
• Put the first beaker with calibration buffer in the beaker holder.
• Place the electrode holder on the top of the beaker and secure it by turning clockwise.
• Immerse the pH and the temperature probe approximately 2 cm (0.8”) into the buffer paying
attention not to touch the stir bar.
To select Electrode calibration screen follow the next steps:
• From pH meter screen press CAL function key then Electrode.
• From Titrator screen press CAL function key then Electrode.
• The electrode calibration screen will be displayed.
Point 1 calibration
• The 8.20 buffer will be selected by default. If necessary press the ARROW keys in order to
select a different buffer value.