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.
Liquid helium is a vital coolant in Magnetic Resonance Imaging (MRI) systems. Air Products supplies cryogenic gases and services to nearly 6,000 MRI sites around the world, and provides gases for over half the world s MRI magnets.iquid helium is a vital coolant in Magnetic Resonance Imaging (MRI) systems. Air Products supplies cryogenic gases and services to nearly 6,000 MRI sites around the world, and provides gases for over half the world s MRI magnets.