Hanna Instruments HI 8521 User Manual

Page 19

Procedure:
• Switch the instrument on after connecting the

pH electrode and the temperature probe.

• Immerse the pH electrode and the ATC probe

into a neutral pH buffer solution (pH 7.01
for technical buffers, or pH 6.86 for NBS
buffers).
Shake briefly and wait 1-2 minutes for thermal
equilibrium.

• Press the CAL key. The symbol "d1" will appear

on the display. For calibration with technical
buffers (pH 7.01), press CAL key again
and "t1" will appear on the display.
(Note: the "pH" symbol will be flashing
throughout the calibration procedure).

• Press the CON key. The buffer value will be

displayed on the right LCD.

• Allow 1-2 minutes for the pH reading to stabi-

lize.
The pH reading will be temperature compensated.
E.g. if the buffer temperature is at 25°C, the right display will
show "pH 7.01". If the buffer temperature is at 20°C, the display
will show "pH 7.03" (see page 23).

If "Err4" appears the calibration solution is wrong.
Repeat the process using fresh buffers.

Note: If you are not using the ATC probe, refer to page 22 to

manually correct for temperature.

• Press the CON key again to accept the buffer value.

The first point calibration is now complete.

• If the pH/mV key is pressed at this point, the cali-

bration process is ended and only the offset of the meter is
calibrated. This is known as one point calibration. For greatest
accuracy, however, it is recommended that a two-point calibra-
tion is performed.

• Rinse the electrode and the temperature probe before immersing

them into pH 4.01/ pH10.01 (or 9.18) calibration buffer, shake
briefly and wait for thermal equilibrium.

°C

CON

CAL

CON