4 D
EGAS THE
S
AMPLE
Heating stations, sample tubes, and heating station adapters may be very hot.
n
Wear the proper gloves and hold the sample tube by the upper part of the stem.
n
If the adapter has a handle, hold the adapter by the handle.
n
Do not place fingers inside the heating stations. The stations may be very hot.
n
Do not place adapters near any combustible material or touch them with fingers.
n
Do not place a hot adapter on a unprotected surface such as a countertop. The
adapter may burn the surface.
n
Failure to observe these precautions may result in severe burns.
n
The vacuum fitting for the sample tube may be hot enough to cause burns after the
sample has been heated. Wear the cotton gloves supplied in the accessories kit
and handle the fitting carefully to avoid burns.
There are three methods of sample preparation:
n
Vacuum preparation.
The sample is heated as a vacuum is applied to the sample tube to
remove moisture and other contaminants. This method should be used only with materials
which are not likely to fluidize.
n
Vacuum-backfill preparation.
The sample is heated as a vacuum is alternately applied and
then flows gas into the sample tube to remove moisture and other contaminants. The
alternating process may be repeated several times. The instrument is designed for low-
pressure backfilling only.
Do not exceed 5 psi regulator pressure when backfilling sample tubes. 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.
n
Flowing gas preparation.
The sample is heated as the operator flows gas into the sample
tube to remove moisture and other contaminants.
Samples that contain a high level of moisture could benefit from a higher flow rate
than 5 psi regulator pressure when using the flowing gas method. A flow rate up to
50 cm
3
/min (approximately 16 psi regulator pressure) may be used to aid in
purging moisture from the sample when using flowing gas preparation only.
4 Degas the Sample
VacPrep Operator Manual
061-42802-01 (Rev B) — Apr 2021
4 - 1
