Specifications

Transmitter M400/2(X)H, M400G/2XH 39

Printed in Switzerland 30 031 683

7.3.1 One-point calibration for amperometric oxygen

sensors

Enter Oxygen calibration mode as described in section 7.1 “Enter Calibration Mode”.

A one-point calibration of oxygen sensors is always either a one point slope (i.e. with air) or a

zero (offset) calibration. A one point slope calibration is done in air and a one point offset cali-

bration is done at 0 ppb oxygen. A one-point zero dissolved oxygen calibration is available but

not normally recommended since zero oxygen is very hard to achieve. A zero-point calibration is

only recommended if high accuracy at low oxygen level (below 5% air) is needed.

Select 1 point followed by either Slope or ZeroPt as the calibration type.

Press [ENTER].

Adjust calibration pressure (CalPres) and relative humidity (RelativeHumid), which are applied

during calibration. Press [ENTER].

Place the sensor in the calibration gas (e.g. air) resp. solution. Press [ENTER].

Depending on the parameterized Drift control (see chapter 8.2.3.4 “Parameters for oxygen mea-

surement based on amperometric sensors”) one of the two following modes is active.

7.3.1.1 Auto mode

NOTE: For a zero point calibration the Auto mode is not available. If Auto mode has been config-

ured (see section 8.2.3.4 “Parameters for oxygen measurement based on amperometric sen-

sors”) and an offset calibration will be executed, the transmitter will perform the calibration in

Manual mode.

Enter the value for Point 1 including a decimal point and units. The value in the second text line

is the value being measured by the transmitter and sensor in the units selected by the user.

As soon as the stabilization criteria have been fulfilled the display changes. The display shows

the calibration result for slope “S” and offset value ”Z”.

In case of a successful calibration, the calibration values are stored in the cal history* and taken

over (Adjust), stored in the cal history* and not taken over (Calibrate) or discarded (Abort).

* only available with ISM sensor. The values will be stored in the sensor.