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.
Even when you add the weight of the ball itself, it is lighter than the amount of water that would fit in the same space. This is called buoyancy. Helium is even lighter than air. A liter (about a quart) of air weighs about 1.25 grams (much less than an ounce) â thatâs not very much. But a liter of helium weighs even less â only 0.18 grams (a tiny fraction of an ounce). A balloon thatâs 1 foot (30 centimeters) in diameter holds about half a cubic foot of helium, which is the same as 14 liters. This means the balloon will weigh about half an ounce (14 grams) less than the same sized balloon filled with air.