Sample Preparation VacPrep 061
2-20 Feb 2013
9. After the sample is sufficiently degassed, remove the sample tube from the heating station.
Leave the VAC/GAS control knob in the VAC position.
10. Place the sample tube, with the vacuum fitting still in place, in a cooling station.
11. When the sample has sufficiently cooled, turn the VAC/GAS control knob to the OFF
position and then to the GAS position.
12. Allow the gas to flow for approximately 30 seconds; then turn the VAC/GAS control knob
to the OFF position.
13. Loosen the knurled retaining nut and slide the sample tube out of the vacuum
fitting. Quickly insert a stopper into the sample tube.
14. Place the vacuum fitting in a cooling station until the next sample is attached.
15. Reweigh the sample tube with stopper and sample to ensure that the correct sample weight
is recorded.
Keep the sample tube attached to the vacuum fitting while cooling to prevent
contamination from the ambient atmosphere.
Backfilling the sample tube increases its pressure to a level greater than atmospheric
pressure. If the gas pressure is greater than the recommended maximum of 5 psig (35
kPag), the sample tube could be ejected from the fitting or broken.
The weight recorded at this step may be compared to the weight recorded before
preparation to determine if adequate degassing has occurred.
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