The time limit for. shipping a POV is the same as for travel and HHG transportation limits (JTR Para 5366, POV. Transportation Time Limitation), 1 year from the date of retirement/separation with severance. pay or 180 days from the date of separation.
The envelope is the large bag that holds the helium gas. The envelope is generally cigar-shaped, for aerodynamic purposes, and made of a durable, airtight, lightweight fabric (polyester composites) that is much like the fabric of a space suit.
In chemistry, compressed helium is used as a carrier gas for an instrument called a Gas Chromatograph. Its role is propel other molecules through a long tube where they gradually separate and then are detected at the end. It is used because it is so inert and won't interfere with the molecules you're trying to detect. Compressed helium is also used to produce an extremely cold environment. Scientists can almost reach absolute zero with compressed helium. davenpoc Â· 7 years ago.