"Blanche" wrote in message
...

Per FAA and other rules, O2 containers must be checked and certified
every 5 years. Refilling the tank varies depending on the FBO doing
the refill.

Oddly enough, I am unable to have the tank refilled at a medical
supply shop because I don't have a prescription for O2.

www.mhoxygen.com
www.aerox.com
www.c-f-c.com/supportdocs/abo1.htm
www.aviationoxygen.com

for details.
http://www.avweb.com/news/pelican/182079-1.html (for more details and
refutation of some myths).