19
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
c) After testing aggressive chemicals and after electrode is cleaned
d) When high accuracy is required
e) If the pH calibration expired warning is displayed during measurement. Every time
you calibrate the instrument clean the electrode (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, 8.30 and 10.01 pH. For a single point calibration any of the three buffers may be used,
but using 8.30 pH is recommended.
Note:
The
HI 84431
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. Open fill hole on electrode.
• 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 electrode 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 8.30 buffer will be selected by default. If necessary press the
ARROW
keys in order to
select a different buffer value.