mah writes:

1. Have you considered getting an aluminum or carbon fiber tank for the
oxygen?

Yes, I replaced my thick(?) steel tank not long ago. I thought I should
do something interesting while I was replacing. It turned out that there
was no big benefit but the costs (financial and time/approval-wise) were
high as I recall.

We changed to them on our ambulance and had a decrease in
weight. This might help with your ability to add a pound or two of
carried weight.

I'm not obsessed with shedding weight. (That was someone else.) I'm
trying to eliminate hassle.

Second, the filled volume is a couple of cubic feet delivered
higher than a similar size steel cylinder. Same external size with
thinner walls means more volume at the same pressure. Check with your
supplier for details. This might mean fewer refills. But you would
have to recalibrate your usage chart.

It's usually just one or two of us sucking oxygen. I appreciate the
advantage of greater capacity, but if I really want to stretch the
duration I'll go with an electronic regulator (or two). I suspect that
the cost (in the long run) will be lower.

2. Is the system high pressure or low pressure to the front of the
aircraft? If high pressure up front, you could possibly back fill by
putting a T connector just before the regulator and be able to refill
from the cockpit.

Yeah, I briefly thought about that too. I'm fairly sure that there's a
regulator between the tank and the outlets that would cause problems.

Again, not an A&P or someone knowing the rules. Just using the problem
presented to exercise my mind.

I appreciate it.

--kyler