Hanna Instruments HI 84429 - Manual (Page 19)

19
ELECTRODE CALIBRATION PROCEDURE
It is recommended to calibrate the instrument frequently, especially if high accuracy is required.
The pH range should be recalibrated:
a) Whenever the pH electrode is replaced
b) At least once a week
c) After testing aggresive chemicals and after electrode is cleaned
d) When extreme accuracy is required
e) If the pH calibration expired warning is displayed during measurement. Every time
you calibrate the instrument use fresh buffers and perform an electrode Cleaning Procedure (see
page 41).
PROCEDURE
A single, two or three-point calibration can be performed, using the 3 buffers 4.01, 6.00 and
8.30 pH. For a single point calibration any of the three buffers may be used, but using 8.30 pH
is advised.
Note: The HI 84429 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 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 reference electrodes 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.