Measuring Calibration - Knauer K-7400 Benutzerhandbuch

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Measuring calibration

SOP 3
Any performed pre-calibration deletes the existing measuring
calibration, because it is not valid for the new measuring head!
5. If you get „not successful" the sample is not frozen. Please check
that
 the sample is a 0 mOsm/kg one
 a valid measuring head is proper connected to the instrument
and repeat the pre-calibration.
Normally a two point calibration is sufficient.
Calibration must be performed very carefully. A confusion of the
calibration solutions will affect all later measurements and give
incorrect results.
Up to three calibration points are possible, two are necessary. On any of
the second row fields the desired calibration concentration can be
selected. After this the calibration run is started by pressing the
START/STOP button.
The first field is fixed on „0000". On the other fields the choices are ----,
%%%%, 50, 100, 150, up to 1900, 1950, 2000 in steps of 50
mOsmol/kg..
Selecting „----" the corresponding calibration point will be deactivated.
The selection of „%%%%" deactivates all other calibration points except
„0000". Simultaneously the displayed measurement results will be shown
in % of this calibration point instead of „mOsmol/kg".
At least two calibration points must be active, the „0000" and one of
the others.
The calibration point remains active until a new valid value for the
selected field is created. If a calibration run is not successfully finished
the last calibration value becomes reactivated.
Performing a Calibration
1. Prepare the instrument according SOP 1 for a measurement of
deionised water.
2. Set the first field in the second row of the CALIBRATE screen to
„0000".
3. Press the start key. While the calibration is running the screen
displays the selected calibration point, the sample temperature and
the elapsed time.
0000 mOsmol > +5.43°C
01:23
At any time the run can be interrupted pressing the STOP key.
4. After finishing the run on the screen is displayed
0000 mOsmol > -0.00°C<
To accept this value presses the START key again. An earlier
measured calibration will be overwritten. Pushing any other key the
Using the Osmometer K-7400
o.k.? <start>