Calibration; Why Calibrate; When To Calibrate; Calibration Procedures - wtw Oxi 7310 Operating Manual

Oxi 7310
ba75931e03 12/2011
5.2

Calibration

5.2.1 Why calibrate?

D.O. probes age. This changes the slope of the D.O. sensor. Calibration deter-
mines the current slope of the sensor and stores this value in the instrument.

5.2.2 When to calibrate?

 After connecting a sensor
 Routinely within the framework of the company quality assurance
 When the calibration interval has expired

5.2.3 Calibration procedures

The Oxi 7310 provides 2 calibration procedures:
 Calibration in water vapor-saturated air.
®
Use an OxiCal air calibration vessel for calibration.
 Calibration via a comparison measurement (e.g. Winkler titration according
to DIN EN 25813 or ISO 5813). At the same time, the relative slope is
adapted to the comparison measurement by a correction factor. When the
correction factor is active, the [Factor] indicator appears in the measuring
screen.

5.2.4 Calibration in water vapor-saturated air (air calibration vessel)

For this calibration procedure, the Comparison meas. setting must be set to Off
in the Calibration menu.
Proceed as follows to calibrate the instrument:
1. Connect the D.O. sensor to the meter.
2. Put the D.O. sensor into the air calibration vessel.
The sponge in the air calibration vessel must be moist (not wet).
Leave the sensor in the air calibration vessel for a time long enough
to adjust.
3. Start the calibration with <CAL>.
The last calibration data (relative slope) is displayed.
Dissolved oxygen
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