Micromeritics FlowSorb III 2305 Operator's Manual page 43

FlowSorb III
Degassing the Sample
Surface areas can be measured reliably with as little as 0.1 m
face or as much as 280 m
termined if sample quantity is adjusted to fall within 0.5 to 25 m
usually is unlikely on the first attempt with a new material. On subsequent analy-
ses, however, sample quantity can be optimized.
Sample weight must be established to express the final result as a specific surface
area (square meters per gram) or as specific volume (cubic centimeters per
gram). True weight is most reliably determined after the sample has been freed of
whatever gases and vapors — especially water vapor — it may have picked up
from the atmosphere. This means the weight is best established after the measure-
ment is completed. The sample tube stems should be stoppered as soon as the
tube is removed. The tube, sample, and stoppers can then be weighed on an ana-
lytical balance and the sample weight established by subtracting the weights of
the tube and stoppers as determined either before or subsequent to the main
weighing.
Except for the warning in Intended Use and Precautions in Chapter 1 against
contaminated and decomposing materials that may give off corrosive or condens-
ing vapors, sample pretreatment (or outgassing) is readily accomplished on the
FlowSorb. However, samples which have been predried, perhaps in a vacuum
oven, will clean up faster. Preconditioning of samples is recommended whenever
possible.
1. Pour the sample into a dry, clean sample tube, being careful to leave some
free space above the sample for the unimpeded flow of gas.
2. Install the tube securely in a holder and attach the holder to the connector la-
beled Degas.
3. Place a heating mantle about the sample (refer to Installing a Heating Man-
tle in Chapter 2).
4. Plug the heating mantle power cord and thermocouple into their appropriate
connectors.
5. Specify the desired temperature using the Temp Set dials. The actual tem-
perature to which the sample is being subjected at any time thereafter can be
read on the instrument meter by depressing the Temp switch just below the
instrument display.
Use + to increase
the setting.
Mar 2012
2
. However, results are most accurately and quickly de-
Use – to decrease
the setting.
Degassing the Sample
2
of total sample sur-
2
range. This
3-3