Micromeritics GEMINI VII KEYPAD, Руководство оператора

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D Analyze Samples with a Total Surface Area of 1.0
m2 or Less
b. Determine the number (n) of glass beads needed to equal the sample volume:
where
0.014 cm
3
= approximate volume of one bead
3. Outgas the sample in the sample tube at an appropriate temperature for an appropriate
amount of time.
4. Install the sample tube (containing the outgassed sample) onto the analysis port and the
sample tube (containing the glass beads) onto the balance port.
5. Specify a one-point measurement (P/P
0
= 0.05 to 0.1) so that the initial free-space meas-
urement can quickly be determined; then perform the measurement.
6. Using the measured free space absolute value and the following relationship, determine the
mass of glass beads to remove from (or add to) the balance tube to reduce the free-space
imbalance:
where
2.515 g/cm
3
= density of glass beads
3.53 = thermal correction (no units)
Note that the volume of one glass bead is approximately 0.014 cm
3
. Therefore, if the
measured free space is less than 0.02 cm
3
, it is unnecessary to correct the free
space.
7. Use a beaker of warm water to bring the balance tube to room temperature before removing
it from the balance port of the Gemini to remove (or add) glass beads. This prevents con-
densation of moisture from the laboratory atmosphere onto the cold glass beads.
8. Remove the balance tube:
n
If the measured free space is negative (–), add the calculated mass of glass beads into the
balance tube.
n
If the measured free space is positive (+), remove the calculated mass of glass beads from
the balance tube.
9. Reinstall the balance tube onto the balance port of the Gemini analyzer.
For subsequent samples of the same material, use the same mass of sample that was
used for the initial sample so that the original bead quantity may be left undisturbed on
the balance port.
D - 2
Gemini VII Keypad Operator Manual
239-42801-01 (Rev E) — July 2021