Thermo Scientific Orion Star User Manual page 33

i . A manual calibration involves performing a Winkler titration and using
that sample as a calibration standard . The oxygen level result from the
titration is entered in a manual calibration as the dissolved oxygen value .
This correlates the meter input to the Winkler titration . This method is
inherently less accurate, due to the possibility of titration errors .
d . – A zero point calibration is performed in an oxygen-free solution .
A zero point calibration is not generally required unless measurements will
be taken below 10% saturation or 1 mg/L . Zero the probe when using a new
membrane, using fresh filling solution or when measuring dissolved oxygen
levels below 1 mg/L . An air calibration should be performed prior to the zero
point calibration .
2 . Allow the probe and calibration standard (water saturated air, air saturated water,
Winkler standard or oxygen-free solution) to reach equilibrium .
3 . In the measurement mode, press
line, press
the calibration .
4 . Wait for the dissolved oxygen reading to stabilize .
a . If an air calibration is performed, the meter will display 102 .3%
and automatically return to the measurement mode .
b . If a water calibration is performed, the meter will display 100 .0%
and automatically return to the measurement mode .
c . If a manual calibration is performed, wait for the mg/L icon to stop flashing
and enter the dissolved oxygen value by pressing
be changed is flashing, press
digit and continue to change the digits until the meter displays the correct
dissolved oxygen value . Once the dissolved oxygen value is set, press
until the decimal point is in the correct location .
d . If a zero point calibration is performed, the meter will display 0 .00 and
automatically return to the measurement mode .
Thermo Scientific Orion Star
until the % sat or mg/L icon is shown and press
and Star Plus Meter User Guide
™
Polarographic Dissolved Oxygen Technique
until the arrow icon points to the bottom
/ to change the value of the flashing
to begin
until the first digit to
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