Micromeritics VacPrep Operator's Manual page 56

4 Degas the Sample
8. Allow the sample to degas for the required length of time. One to two hours is typical for
many samples at temperatures above 200 ºC. To determine the optimum time, select the
highest safe temperature for the sample, then degas it for various intervals, determining the
surface area after each interval.
For example, degas the sample for 15 minutes, then measure the surface area. Repeat this
process until the surface area no longer increases. The length of time required to reach this
point is the minimum amount of time required to degas the sample.
9. After the sample is sufficiently degassed, remove the sample tube from the heating station.
Do not turn off the gas flow knob.
Keep the gas delivery tube and stopper in the sample tube while cooling to prevent
contamination from the ambient atmosphere.
10. Place the sample tube, with stopper and gas delivery tube still in place, in a cooling station.
4 - 10
VacPrep Operator Manual
061-42802-01 (Rev B) — Apr 2021