[DoctorBeaver (OP)]

Due to my medical condition I have had to have a machine installed in my home that produces oxygen. It's free-standing and uses ordinary air as the input. Oxygen is then pumped to the mask I wear. What does it do to the air to produce that lovely oxygen I breathe to get my lungs working again?

[The Craftsman]

It uses a pressure swing adsorbtion to filter out the nitrogen from ambient air.

heres a link to the wiki with some more technical details
http://en.wikipedia.org/wiki/Oxygen_concentrator [nofollow]

[DoctorBeaver (OP)]

Thank you, Craftsman. So what I'm getting is not pure oxygen. Rather, it's just air with the nitrogen taken out.

[The Craftsman]

Pretty much.  Those machines are typically referred to as oxygen concentrators, which is a solid description of what they do.  Depending on brand and settings you're getting somewhere between 50-95% O2 in contrast to sea level ambient air which has about 20% O2. 

Even the bottled stuff isn't "pure oxygen" but rather high concentrated oxygen, around 95%.  Its made with the same technology you have at home just with an industrial size machine, pressurized into bottles and shipped.  For the most part pure oxygen has few uses outside industrial applications. 

"Pure oxygen" is unnecessary for treatment of respiratory problems.  Your lungs absorb nitrogen as well as oxygen, so with an oxygen treatment the O2 is increased and Nitrogen decreased to correlate to the loss of respiratory function, and your body gets the O2 it needs.

[Bored chemist]

I'm not sure about these.
"Even the bottled stuff isn't "pure oxygen" but rather high concentrated oxygen, around 95%."
and
"Its made with the same technology you have at home just with an industrial size machine, pressurized into bottles and shipped.  "
My elderly copy of the pharmacopoeia says that medical oxygen has to be >99% (with the balance argon, nitrogen or hydrogen).
Also I think most industrial plants still rely on distilation to make pure oxygenn, rather than PSA.

[The Craftsman]

You're absolutely right.  I was generalizing when I shouldn't have.  Medical grade is 99% and made through distillation in large quantities.  The lower grade stuff is typically done locally by PSA.  I honestly don't know which is more prevalent, my experience is just with the PSA stuff (experiential bias, it happens).  Thanks for the correction.

[DoctorBeaver (OP)]

Thanks again, Craftsman & BC

[Geezer]

Also I think most industrial plants still rely on distilation to make pure oxygenn, rather than PSA.

Not to be pedantic [] but would that not be liquefaction rather than distillation?

[Bored chemist]

Also I think most industrial plants still rely on distilation to make pure oxygenn, rather than PSA.

Not to be pedantic [] but would that not be liquefaction rather than distillation?

Not to be pedantic, unless you distill it you don't get the fractionation needed to splt the N2 from the O2- of course, they do need to liquefy it first, but that's not the whole story.

[DoctorBeaver (OP)]

Right, now I'm lost  []

[Geezer]

Right, now I'm lost  []

Fear not!

I was making the point that the first step in the process is to liquefy the oxygen to separate it from the other components in air. Oxygen has the highest boiling point, so it's the first component to liquify as the air is cooled. While that is true, the resulting liquid is still not pure oxygen. If greater purity is required, it is necessary to distill the output from the liquefaction process.

[The Craftsman]

Semantics.  Distillation is a general industry term for the process used by management and marketing.  The conversation has descended into: what is the appropriate context to use technical engineering nomenclature. 

That aside I think a new post and discussion on the process would be interesting.  Anyone game?

[peppercorn]

Anyone know which PSA device on the market gives the greatest flow output (for, say 50% conc.)?

Also what's the mechanical efficiency of a PSA?