Makin' Nitrox the Easy Way

[diveongas]

I don’t know if any Nitrox Blenders out there are doing this, but I’ve stumbled onto a possible solution for those, like me, that are tired of moving H and K bottles around. A friend of mine bought the contents of a storage unit that had been abandoned, in it were 2 medical oxygen concentrators both able to make 5 liters per minute each. I thought why not feed the Nitrox stick with these?

I calculated that I could make 28.3% with my (suitable for O2) compressor. I filled 4 cylinders, back to back, and they all came out 29.2%. Knowing that medical devices are generally spot on for specs to avoid lawsuits, I was able to calculate that my compressor only delivers 3.1 CFM over a 3500 PSI fill rather than the rated 3.5 CFM.

I’m satisfied as is. A 29 gives almost a 130 END (FFW) at 1.4. This is also very convenient for pumping on top of helium for those certified to do such things.

WARNING: DO NOT put oxygen into the intake of any compressor as it can explode, causing possible injury and death. Only use an approved compressor and nitrox stick for blending purposes. The blending of high pressure gases is inherently dangerous if performed with inadequate knowledge, technique, or equipment. Additionally, improperly prepared breathing gases can prove fatal to the end user.

[tflaris]

Thanks for the warnings. If you could use smaller print and maybe have a voice over that would be cool also.

BTW Thanks for the info. Very Cool.

[AB8CD]

I have wondered about this for a while... My aunt has a similar machine that puts out O2 at about 96% according to my sensor. It seems like a workable situation for a nitrox mix. I have wondered if others have taken advantage of these machines for diving mixes.

[aainslie]

Check what exactly is in that gas. You'll find it to be argon rich. Fine if you'e cool with narcosis.

[FW]

Check what exactly is in that gas. You'll find it to be argon rich. Fine if you'e cool with narcosis.

Ooh, good warning! It sounded too good to be true

[DA Aquamaster]

Check what exactly is in that gas. You'll find it to be argon rich. Fine if you'e cool with narcosis.

Can you elborate on that? Why is it rich in argon? Is it concentrated in the same more or less 5 to 1 ratio as the O2?

[FW]

Can you elborate on that? Why is it rich in argon? Is it concentrated in the same more or less 5 to 1 ratio as the O2?

Yes, the concentrators typically only remove Nitorgen, and concentrate everything else.

I know all the pitfalls of Wiki, but here is a brief description of the process.
http://en.wikipedia.org/wiki/Oxygen_concentrator

[diveongas]

Check what exactly is in that gas. You'll find it to be argon rich. Fine if you'e cool with narcosis.

Good point, which I had already been considered. Each (both) concentrators produce 5 Liters per minute of gas that is 95% oxygen. We'll just assume worst case that the other 5% is Argon. 5 LPM = .1766 CFM which times 2 (two concentrators) = .3532 total CFM. 5% of that is .0177 CFM. Now divide .0177 CFM by the compressor's pumping rate of 3.1 CFM and you get 0.57% additional Argon in my EAN29 nitrox blends. Since there is already 0.934% Argon in the atmosphere, you're now up to 1.5%. I don't believe a half percent more argon should be meaningful to me, but the narcosis sensitive types like youself might want to consider cutting your calculated END back 30~40 feet if using blends made in this fashion.

Jim Charles

[AB8CD]

And the gauntlet is thrown... Before it get's too heated please let me say how much I truly enjoy the education I gain from this board!

Dan

[aainslie]

That sounds about right. Since you're going from 21% to 30%, an increase of around 50%, the argon should go up in proportion. I agree that it's probably too small to be a worry.

A BIGGER concern would be anyone with a rebreather that thinks they've found a cheap way to make oxygen. There, this is an incredibly bad idea. If they're using O2 that's 5% Argon, and the argon stays in the loop while the O2 is consumed, the loop can get very narcotic very quickly. On OC it's not as big an issue.

It came up on rebreatherworld a couple of years ago. This thread just reminded me of it.