Why have I never seen anything like this for Scuba?

[kidspot]

http://www.tri-medinc.com/TM/page38.html

I know you can get membrane systems for a compressor, but scroll down the page a bit and they have units that will pull 94% O2 and then fill a small bottle up (only 2200psi, but add in a booster...)

Just wondering why something like this would not work for filling deco/rebreather O2 bottles... other than needing an Rx for it

Is the O2 content too low? Too many contaminants?

Aloha, Tim

P.S. I'm not considering getting one, just wondering why I've never seen something like it for scuba.

[Mark Vlahos]

I was stumbling around the web a while ago, and wondered the same thing. Just a little more checking and I came to the conclusion that these things are tightly controlled by the medical community, so getting a new one would be difficult without a prescription. For most people it would just be easier to keep doing things the way we have been doing it.

It sounds kind of ghoulish and predatory, but if you could find one at an estate sale you might be on to something.

Mark Vlahos

[kidspot]

I saw one for sale on craigslist a few weeks back - $2k almost new ...

[AzTek Diver]

The O2 concentrator is the easy part, do a search on ebay, there's tons. The money goes to the booster to get the O2 up to 2200psi, another $3500+. If I'm going to pay that kind of money for a booster, it's going to haul a** and will be used for lots of different gases.

[rogerbly]

and 02 is relatively cheap... less than $20 per 300cf T-bottle. a booster is nice, but you can survive without a booster and fill deco bottles to 2,000psi.

[kidspot]

and 02 is relatively cheap... less than $20 per 300cf T-bottle. a booster is nice, but you can survive without a booster and fill deco bottles to 2,000psi.

WOW - I checked last month and it was $125 for 200cf here :S

[Gene_Hobbs]

You guys might enjoy this one:

Wells JM, Dinsmore DA. Evaluation of Atmospheric Oxygen Concentrators as a Source of Oxygen and Oxygen Rich Mixtures for Treatment of Diving Accident Victims in Remote Areas. In: Brueggeman P, Pollock NW, eds. Diving for Science 2008. Proceedings of the American Academy of Underwater Sciences 27th Symposium. Dauphin Island, AL: AAUS; 2008. RRR ID: 8023

[kidspot]

Thank you Gene - I think that is an ingenious way of dealing with things in the one unit which delivered pure O2 on the first half of the inhale cycle followed by plain air for the second, which filled the dead air spaces.

I wonder if it is possible to feed the 90% O2 back in for a second pass and have it remove the rest of the nitrogen?

[AzTek Diver]

I wonder if it is possible to feed the 90% O2 back in for a second pass and have it remove the rest of the nitrogen?

In the large high end O2 concentrators that's exactly what they do, not through the same bed, but through a second one. The speed/dwell also has alot to do with the O2% produced.