Thermo Orion Star, User Manual

Page: 51 / 111

VIII-9
Orion Star Series Meter
Thermo Electron Corporation
Dissolved Oxygen Technique
4 . While the electrode signal is stabilizing, the meter will
flash a dissolved oxygen reading (based upon the current
calibration data) in the main field . Once the input has
stabilized, 100 .0 % saturation will be displayed for three
seconds .
5 . The slope value ( ) will then be displayed . The meter
will return to measure mode .
Calibration to the Winkler Titration Method
Many regulatory agencies require the determination of dissolved
oxygen in water to be referenced to the Winkler Titration
Method . The Meter allows the user to scroll the dissolved
oxygen measurement to correlate with the value obtained from
the Winkler titrated sample . The
calibration function must
be enabled in Setup before the calibration is started .
1 . Place the dissolved oxygen probe into the sample . Make
sure that the water level is high enough to fully submerge
the probe thermistors, which are located inside the metal
band above the membrane cap . Ensure that the stirring is
vigorous enough to provide adequate mixing yet not forceful
enough to create a vortex in the beaker . Ensure that there
are no air bubbles accumulating on the membrane .
Note:
Some magnetic stirrers generate enough heat to change
solution temperature. To avoid this, place a piece of cardboard,
foam rubber or other insulating material between the stir plate
and sample beaker.
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