Advanced
®
Cryoscope Model 4250 User’s Guide
recorded internally. Continue loading and testing standard samples at
the first calibration level until prompted by the display for a sample at
the second calibration level.
When six calibration tests have been acceptably completed at the
first calibration level, the instrument will calculate and store the
mean of the raw values of the closest tests, then prompt the operator
for samples at the second calibration level. The calibration will not
actually be changed until six calibration tests have been acceptably
completed at both calibration levels.
When six calibration tests have been acceptably completed at the
second calibration level, the instrument will calculate and store the
mean of the raw values of the closest tests, recalibrate the readout
and display “Calibration Complete”.
3. At “Calibration Complete” one may press STOP to return to
“Cryoscope Ready”, CALIB to restart the calibration sequence or
START to lower the operating head and start a regular freezing-
point test.
NOTE If the instrument has lost all previous calibration data and you
see the message “Recalibration Needed”, pay close attention to
the displayed prompts. You will be requested to run a slightly
different sequence than described above.
Celsius and Hortvet
Model 4250 cryoscopes are factory-calibrated and shipped with the dis-
play set for -m°C, but test results may be displayed and calibration
accomplished in either -m°C or -m°H, as selected via SETUP (see
Chapter 2, Select Display mH/mC). Changing between these two scales
does not require recalibration. However, to avoid confusion it is prudent
to use the same scale as your associates; the units used should always
be reported. In either case you should document your selection.
If you permanently change scales:
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