Flowsorb Iii 2305 - Micromeritics FlowSorb III 2305 Operator's Manual

Performing a Single-Point Surface Area Measurement
2. Prepare a Dewar of liquid nitrogen for the sample to be analyzed. The level
of liquid nitrogen should be approximately 1 to 2 cm (0.4 to 0.8 in.) below
the Dewar lip.
3. Check the level of the Cold Trap Dewar; replenish if necessary. Avoid re-
plenishing the Dewar during analysis.
4. The steps for the remainder of the analysis depend on whether you are using
a FlowSorb III 2310 or 2305; advance to the appropriate set of instructions
and proceed accordingly.

FlowSorb III 2305

1. Raise the Dewar of liquid nitrogen about the sample and lift up on the
Dewar tray until it locks into position; this starts the analysis.
•
After approximately one minute (five minutes for the Long Path) the
Threshold light begins to flash and the instrument display shows data ac-
cumulation.
•
Ensure that the flowmeter float returns to its normal position before data
accumulation begins (Threshold light flashing). If it does not, wait until
the analysis finishes (flashing ceases) and restart the analysis using the
LONG path or a lesser quantity of sample.
•
When the flashing ceases to no more than once in 15 to 20 seconds (ap-
proximately three or four per minute), or the indication with Det de-
pressed has returned to 0.02 or less, adsorption is complete.
2. Record the value if desired. This value represents the sample surface area in
square meters obtained from the adsorption of nitrogen gas. The adsorption
peak is not as sharp and clean as the desorption one and cannot be inte-
grated with quite the precision of the latter. However, surface areas obtained
by adsorption and desorption are virtually identical for many materials when
the reference potentiometer is properly adjusted (described in Appendix B).
The desorption procedure is unnecessary when this is found to be the case.
3. Depress the Clear SA Display button to clear the display for registration of
the desorption value.
4. Remove the Dewar of liquid nitrogen; allow the sample to equilibrate to
room temperature so that desorption data can be calculated.
You may wish to immerse the sample tube in a beaker of room temperature
water to speed up the warming process.
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FlowSorb III
Mar 2012