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 an experiment, 40.0 mol of helium gas is collected over water. The total volume of gas collected is 0.224 L. Under similar conditions, the gas is collected over two other liquids, A and B. The total volume of gas collected over A and B are 0.222 L and 0.227 L, respectively.