31
SECTION 3,
continued
3.2
Calibrating the Meter
The sens
ion
4 Meter is designed to auto-recognize and calibrate
on 1.68, 4.01, 6.86 or 7.00, 10.00, and 12.45 pH buffers.
Calibrating with buffers that have pH values other than these
requires a modified procedure. Each channel requires
independent calibration.
Hach recommends a daily two-point calibration using buffers that
bracket the sample pH. This will verify the electrode is working
properly and allow the slope value to be stored.
3.2.1
Performing a Calibration Using pH 1.68, 4, 6.86, 7, 10, and 12.45 Buffers
1. Select the desired channel. If using a probe without a
temperature sensor, see Sections 2.3.2 on page 22 and 2.6 on
page 23 for information about obtaining and using a
default temperature.
2. Prepare pH buffers that bracket the sample pH according to
the electrode instruction manual. the meter can be calibrated
with two to five autorecognized buffers.
Note: Use a 6.86 or 7.0 pH buffer for the mid-range buffer. To view or
change the setting for the mid-range buffer see Section 3.1.5.
Note: The pH values for the buffers are given for 25 °C. If the sample
temperature is not 25 °C, the pH values displayed for the buffers will
reflect the correct pH value for the sample temperature.
3. Press
I/O/EXIT
to turn the instrument on. Select the desired
channel. If necessary, press the
P
H/mV
key to get into the pH
reading mode (
pH
will be displayed).
4. From the pH reading mode, press
CAL
.
CAL
and
?
will
appear in the upper display area, along with
Standard
and
1
.
5. Place the pH electrode in one of the buffers.
6. Press
READ/ENTER
. The temperature and pH values will be
updated until a stable reading is reached.
Note: If the meter is measuring in pH mode, it automatically moves to the
next calibration step when stabilization is reached (indicated by
three beeps). If measuring in mV mode, the three beeps will still
sound when the stabilization occurs, but you must press
ENTER
to
