[FAR 91.211](http://www.ecfr.gov/cgi-bin/text-idx?idno=14;region=DIV1;type=boolean;c=ecfr;cc=ecfr;q1=oxygen;rgn1=Section;op2=and;rgn2=Section;op3=and;rgn3=Section;rgn=div8;view=text;node=14%3A2.0.1.3.10.3.7.6) tells us ***when*** supplemental oxygen is required, but it's not very specific as to ***how*** that oxygen is to be provided. [FAR 23.1447](http://www.gpo.gov/fdsys/granule/CFR-2011-title14-vol1/CFR-2011-title14-vol1-sec23-1447) gives some information about *installed* systems, but I can't find much on FAA requirements if you're using a *portable* system (cylinder, regulator, and cannula/mask like [a Mountain High system](http://www.mhoxygen.com)).

Are there specific requirements/recommendations regarding portable oxygen equipment for Part 91 General Aviation, or can you just pick up a a medical or welding tank, stick a regulator on it, and pass out masks to your passengers?