User`s guide

Routine Maintenance
285
Stainless Steel Tubes
In stainless steel sample tubes, the adsorbent bed is usually retained
using stainless steel gauze disks.
New stainless steel sample tubes already contain the initial retaining
gauze disk at the front (grooved) end of the tube. Older tubes, which
are being repacked, usually need to have this initial gauze disk
placed in the correct position. To do this, we strongly recommend
that you use the gauze-loading rig. See Gauze-Loading Accessory on
page 286.
To pack your stainless steel tube:
1. Ensure that the initial gauze disk is in place.
2. Pack the stainless steel tube by pouring the adsorbent
material into the rear end of the tube. Use a funnel to
completely fill the tube.
NOTE: Some official methods give details as to the specific mass of
adsorbent to be added to the tube.
3. Compact the packing by tapping the tube on a firm
surface so the adsorbent settles, leaving an unfilled gap
of approximately 1 cm depth at the end of the tube.
4. Insert the second (rear) retaining gauze disk and spring
into this gap.
Glass and Glass-Lined Stainless Steel Tubes
In glass and glass-lined stainless steel tubes, the adsorbent is packed
in the same way as you would pack stainless steel tubes. Normally,
the adsorbent is held in place by glass wool plugs.
It is necessary to ensure that an adequate glass wool plug
(approximately 0.5 cm long) is used to prevent the packing from
moving during the thermal desorption sequence. Ensure that all the
packing, including the glass wool plug, is contained in the center of
the tube, and that there is a gap of at least 1 cm at each end.