Hanna Instruments HI 84502 - Manual (Page 19)

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, but daily is advised
c) After testing aggressive chemicals and after the 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 use fresh buffers and clean the electrode (see page 40).
PROCEDURE
A single one, two or three-point calibration can be performed, using four predefined buffers
4.01, 7.01, 8.20 and 10.01 pH. For a single point calibration any of the four buffers may be
used. If the 7.00 pH end point is set the 7.01 pH calibration point is recommended, or else
use 8.20 pH.
Note: The HI 84502 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 the beaker that will be used for calibration.
• Remove the protective cap and rinse the electrode 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 and
press STIR.
• Immerse the pH and the temperature probe approximately 2 cm (0.8”) into the buffer,
paying attention not to touch the stir bar.
To enter Electrode Calibration follow the next steps:
• Press
CAL key then Electrode.
• The electrode calibration screen will be displayed.
• Press
Clear to delete the previous calibration.