10
pH CALIBRATION
Calibrate the instrument frequently, especially if high accuracy is required.
The instrument should be recalibrated :
Whenever the pH electrode is replaced.
At least once a week.
After testing aggressive chemicals.
If CAL INTV tags are blinking during measurement.
Every time you calibrate the instrument use fresh buffers and perform an
electrode Cleaning Procedure (see page 30).
PREPARATION
Pour small quantities of the buffer solutions into clean beakers. If possible, use
plastic or glass beakers to minimize any EMC interferences.
For accurate calibration and to minimize cross-contamination, use two beakers
for each buffer solution. One for rinsing the electrode and one for calibration.
If you are measuring in the acidic range, use pH 7.01 or 6.86 as first buffer and
pH 4.01 as second buffer. If you are measuring in the alkaline range, use pH
7.01 or 6.86 as first buffer and pH 10.01 or 9.18 as second buffer.
PROCEDURE
Calibration has a choice of 5 memorized buffers: pH 4.01, 6.86, 7.01, 9.18
and 10.01.
It is recommended to perform a two or three-point calibration. However, the
instruments also allow one-point calibration, as described on page 12.
THREE-POINT CALIBRATION
Immerse the pH electrode and the temperature probe
approximately 4 cm (1½) into a buffer solution of
your choice (pH 4.01, 6.86, 7.01, 9.18 or 10.01)
and stir gently. The temperature probe should be
close to the pH electrode.
Press
CAL
. The CAL and
1
BUF
tags will appear
and the 7.01 buffer will be displayed on the
secondary LCD.
If necessary, press the
ARROW
keys to select a different buffer value.
CAL
1
BUFFER pH
BUF
pH
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