JUMO 202610.0, Operating Instructions Manual, Page: 41 / 68

41
9 Commissioning
✱
Calibrate instrument,
➩
Chapter 10 “Calibration”, page 42ff.
✱
For high-precision measurements, repeat calibration after 24 hrs.
Oxygen cells must be "run in" before calibration. This means that
the cell is connected to the transmitter and then continuously
operated in air that is saturated with water vapor until the reading
no longer changes.
Note: The vapor-saturated air is several centimeters above the
water surface. The oxygen cell should be as close as possible to
the surface of the water but
must not get wet !
Calibrating only makes sense when the measurement has
sufficiently stabilized. If an oxygen cell is calibrated that has not
been completely run in, then an incorrect slope will be used for the
subsequent calculation of the measurements. To prevent this from
happening, the transmitter monitors the signal stability of the
oxygen cell during calibration. If the signal drift is too large during
calibration, or when a sensor slope of more than 150% is
calculated, an error message will be generated and the calibration
canceled.
Depending on the age, pretreatment and storage conditions, the
oxygen cells, in their original packaging, may require different run-
in times. This is
not a defect.
While the oxygen cell is being run in, the oxygen, which reaches
the cathode from the electrolyte, will be used up by the reduction
at the cathode. Afterwards, only the oxygen will be acquired that
has reached the sensor cathode from the sample medium. During
the run-in time, the oxygen cell will measure an excessive oxygen
concentration. Under unfavorable circumstances, running in may
take several hours.
If, after the end of the calibration, the instrument calculates a
sensor slope of more than 150%, the calibration will be considered
as unsuccessful and the result discarded.
The run-in time should be extended until a constant measurement
is displayed.
Temperature Oxygen content in water
with an air ressure of
101.325 kPA
0 0°C 14.62 mg/l
0 0°C 12.77 mg/l
10°C 11.29 mg/l
15°C 10.08 mg/l
20°C 0 9.09 mg/l
25°C 0 8.26 mg/l
30°C 0 7.56 mg/l
35°C 0 6.94 mg/l
40°C 0 6.41 mg/l