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Advanced
™
Osmometer Model 3250 User’s Guide
4. Stir/Freeze Test
This menu item enables visually and aurally checking the stir and
freeze vibration amplitudes. Please refer to the Stir/freeze amplitude
adjustment section shown later on in this chapter for instructions.
5. Probe Bin Test
This test is used to determine the resistance and bin number of the
sample probe at a specific temperature (-0.093°C). It is essentially the
same as any other sample test except that the sample probe resistance
and correct bin number are determined and displayed, in place of the
sample freezing point.
On entry, the probe bin test will display [Start] Ready?.
1. At [Start] Ready?, pipette or measure a sample of probe bin-
setting fluid into a clean sample tube, place the tube in the freezing
chamber and press the START key. The 3250 will run a special
freezing-point test to determine the sample probe resistance and
bin number.
Note In an emergency, H
O may be used in place of probe bin-setting
fluid for this test. The bin number thus determined will be
acceptable for bin setting though the probe resistance displayed
will be that at the freezing point of the H
O sample used and will
be different from that at a freezing point of -0.093°C.
The display will flash Cooling Sample (as in a normal test) until the
sample probe resistance reaches 4990 ohms. Then the test proceeds
normally except that the display is in ohms rather than mOsm. At
the end of each test, the final display will be the test result in ohms
and the sample probe bin number (e.g., 12345.67 Ohms Bin 10).
2. A test in progress can be stopped by pressing the STOP key.
3. Another test may be run by replacing the sample and pressing
START again.
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