Specifications

Transmitter M400 54
© 02 / 2010 Mettler-Toledo AG, CH-8606 Greifensee, Switzerland Transmitter M400
Printed in Switzerland 52 121 378
The display shows now the values for the phase of the sensor at 100% air (P100) and at 0%
(P0) air.
In case of a successful calibration, the calibration values are taken over and stored in the cal
history (Adjust), only stored in the cal history (Calibrate) or aborted.
If ”Adjust” or ”Calibrate” are chosen, the message ”Calibration successful” is displayed. The
M400 returns to the measuring mode.
7.6 pH calibration
For pH sensors, the M400 transmitter features one-point, two-point (Auto or Manual mode)
or process calibration with 8 preset buffer sets or manual buffer entry. Buffer values refer to
25 °C. To calibrate the instrument with automatic buffer recognition, you need a standard pH
buffer solution that matches one of these values. (See section 8.2.3.2 “pH/ORP parameters” for
configuring modes and selecting buffer sets.) Please select the correct buffer table before using
automatic calibration (see chapter 19 “Buffer tables”).
7.6.1 One point calibration
Enter pH calibration mode as described in section 7.1 “Enter Calibration Mode”.
Select 1 point Calibration. With pH sensors a one point calibration is always performed as a off-
set calibration.
Depending on the parameterized Drift control (see chapter 8.2.3.2 “pH parameters”) one of the
two following modes is active.
7.6.1.1 Auto mode
Place the electrode in the buffer solution and press the [ENTER] key to start the calibration.
The display shows the buffer the transmitter has recognized (Point 1) and the measured value.