6 CALIBRATION
You can reach the Calibration mode directly from the Measurement mode by pressing the CAL
key and entering the Calibration security code. You can also reach the Calibration mode from
the Advanced Setup mode.
6.1
pH Calibration
This unit features 7 preset buffer values (1.01, 4.01, 6.86, 7.00, 9.00, 9.18 and 10.01) for
fast auto calibration. When you calibrate this instrument, you need a standard pH buffer
solution that matches one of these values.
1)
Enter Calibration mode
. While in the Measurement
mode, press the CAL key and scroll to Calibration code
“11”. Press the
ENTER
key again. The upper and lower
display reads “CAL pH”.
NOTE:
If the display reads “CAL OrP”, see section 7.6.2 for
procedures on how to switch from ORP to pH readings.
11
HOLD
6.96
7.00
4.02
4.00
SETUP
HOLD
CAL
59.0
mV
7.00
pH
READY
HOLD
CAL
CAL
pH
SETUP
HOLD
2)
Press the ENTER key
again to begin calibration. The
“CAL” indicator appears at the top of display and the
buffer indicator appears in the bottom left corner of the
display. The upper display shows your present
uncalibrated reading. The lower display indicates one of
the two buffer values used for the first point calibration.
It would either be 7.00 or 6.86.
pH
pH
pH
3)
Press the
▲
or
▼
key
to scroll the lower display to the
buffer value that matches your buffer solution.
4) Make sure the electrode is in the buffer solution. In
ATC, you must also immerse the temperature probe in
the buffer solution. Likewise for symmetrical mode, you
must also immerse the potential matching pin in the
buffer.
pH
5)
Press the ENTER key
to confirm the buffer value and
start the calibration of its first point. The electrode
indicator and CAL indicator both flash. The controller
automatically adjusts the reading to match the buffer
value.
6) The lower display will now show its next lower ‘pH’
buffer. Use
▲
and
▼
keys
to select its second buffer
from one of the 5 preset values. Remove the electrode
from the first buffer, wash and then immerse into the
second buffer. Once the upper display stabilises
press
the ENTER key
, the electrode and CAL indicator will flash. The controller adjusts the
reading to the buffer.
7) After calibrating to a second buffer value, this controller will automatically display slope in the
upper display and zero point in the lower display. You can view the values for zero point and
slope without calibration --- see section 5.1.2 for instruction The zero point and slope are re-
determined after each calibration.
