Is there any difference between a tank of welding oxygen vs medical
oxygen as far as purity, concentration, hazardous impurities, etc, that
would render welding oxygen insufficient (or even dangerous) for helping
to supplement breathing / respiration ?
To be precise it is way less. The air we breath is roughly twenty
percent oxygen. Medical oxygen is nearly one hundred percent oxygen.
The inert components of air are removed from the compressed oxygen
that is used for patient breathing assistance and making ordinary
metals burn and melt together into a single piece of metal.
And what I meant by "way more" was that welding oxygen has a higher
oxygen content (or oxygen concentration) vs ordinary air. So I don't
know why you'd say it's "way less".
And likewise for welding oxygen - yes?
Harry K wrote:
From what I've been reading tonight, ALL forms of compressed oxygen
(Aviation, Medical, Welding) come from the SAME source (a tank of Liquid
Oxygen - LOX) and are transfered to variously labelled tanks and charged
various prices based on the label on the tank.
My guess is that the price differential is caused by liability insurance
and the need to recoup that cost based on the end-use of the gas. The
insurance industry might perceive that aviation oxygen (as a product)
carries the highest risk to the producer / seller, with medical oxygen
less risky, and welding oxygen the lowest risk. Risk in this context
means what sort of incident could happen if the wrong gas is
accidentially sold to the end user, or could happen if the tank fails.
The humidity of compressed oxygen seems to be a red herring. In medical
situations such as the hospital bedside, oxygen supply lines are passed
through a bubbler or some other humidification device to add humidity to
the air. This is a stationary situation where the person is likely to
be on the air supply for an extended period, and humidification is done
more for comfort or to prevent airway irritation than anything else. In
other medical situations (EMS O2 respirator tanks) the air is dry -
because it simply can't supply O2 for an extended period anyways.
And you don't want to get water in your high-pressure tanks anyways - if
only so they don't rust.
Aviation air also can't contain a lot of humidity because (or so the
story goes) the water could freeze at high altitudes and mess up the
supply and metering lines.
So the bottom line is that if you walk into a welding supply store to
buy an oxygen tank, don't let on that you intend to use it to fill your
plane's on-board tank, or you want to make an oxygen tent for your sick
pet. The guy behind the counter will most likely go ape-shit and either
deny your purchase, or force you to buy the more expensive tank -
probably because their insurance company forces them to do that.
The insurance industry plays a far larger role behind the scenes in our
daily lives than we realize. The products we can buy, the services we
use, the way they are delivered or sold to us, etc, exist because the
manufacterers, retails or providers have reached a stable (perhaps even
strained) coexistance with the insurance industry.
FWIW, all oxygen is too dry for extended period use. That is why they
run it through the little bottle thingy first in medical uses.
Also, if you believe in eHow.com
Another aside, so although O2 USP has the same basic source as
industrial gases, it's specified., handled, distributed and tracked
differently. O2 USP has FDA mandated lot numbers to facilitate product
recalls. These lot numbers are tracked all the way to the patient.
Which means that the Plaintiff lawyers play a far larger role,
since most of the insurance company's concerns has to do with keeping
the PL out of their pocket.
I want to find a voracious, small-minded predator
and name it after the IRS.
Oxygen concentrators remove the nitrogen and leave you with about 93%
oxygen. It has no pressure though, and it would still have to be
pressurized to about 10 psi to work for welding. Probably not impossible,
just not practical.
Though real popular with folks who melt glass with smallish torches- a
20pound LP tank and an O2 concentrator is a real popular setup.
Went to find a link for details and found this site-
I guess you can get one for large torches now-- advertised up to
20psi & 15LPM. [and up to $3500]
I noticed my m-i-l has an attachment on her [medical] O2 that lets her
fill a small tank. I don't know what the pressure is-- and I also see
that she still rents the big tanks, so it can't be too efficient.
I see a lot of people getting these machines:
I would imagine there are concentrators available for welding.
As for original question, industrial oxygen should be suitable for
breathing. All compressed oxygen must be free of impurities like oil
because of potential for explosion.
Large scale O2 generation involves cooling air to liquify it, then pulling
off the components: Oxygen, Nitrogen, CO2, Argon, etc.
You CAN get Oxygen by electrolysis of water (plus Hydrogen), but the energy
expenditure is horrendous.
Certainly O2 generators can be powered by chemical means; the Oxygen masks
on airliners rely on chemical release of O2 by the burning of chlorates or
All that said, you can get O2 generators for small applications (bedside,
veterinary, etc.) use, up to, and including, institutional generation, say,
To answer your question directly: Bottled O2 is far cheaper than the
The concentrators work by reverse osmosis. You can travel with them and
use rechargeable batteries. If you are home, immobile, the medical
supplier will often give you liquid and tubing is strung around the
house. For short trips of a few hours, you can take liquid. You hire a
supplier and it is up to him to satisfy all your requirements, tank,
liquid or concentrator.
The bottom line is how confident do you want to be that what comes out
of that refilled tank is, indeed, fit for breathing purposes and hasn't
been contaminated since that point?
The scenario in the posting link later of a single large bottle
refilling known smaller ones is reasonably well controlled; just taking
the next random welding bottle returned from who knows where...errr, not
so much. As someone else pointed out, you don't know what was done with
those bottles previously nor what has been done since w/o the
certification--that's the role it plays.
As for cost; it's a lot like the "N-stamp" nuclear-grade
components--many of them are, in fact, identical to their non-graded
cousins but they've been through the qualifications to prove their
pedigree; the poor red-headed stepchild _may_ be just as good but
doesn't have the papers to prove it.
I presume that the first time that any brand-new O2 bottle is filled
with it's first batch of O2, that it has been cleaned and vacuum
After that point, unless the air pressure in that tank ever falls below
ambient atmospheric pressure, it's hard to see how anything other than
pure O2 could ever re-enter it - even if it was ever connected to a
manifold system where other bottles of similarly-clean O2 are also
I understand that I can buy, or rent, oxy-acetelene tanks. If I buy,
I'm not sure if I can have my bought-tank re-filled and returned to me,
or if I simply exchange it for filled (but used) tank.
If I buy a brand new tank, and if I keep refilling that same tank when I
need more, then I am removing the uncertainty of what could have been in
the tank before it was filled.
And when it comes to refilling returned tanks, is it normal practice to
at least let the tank fully depressurize itself before it's refilled?
Wouldn't that dillute any potential non-oxygen gas or even particulate
contaminent that it *may* have once the tank has been refilled with
it's "way less" because for a given volume of gas,you get only ONE
element;oxygen,while "air" also gives you
Not that they have any benefit,but it's "more" than what you get with pure
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