Can one breathe industrial oxygen

In that same episode, Jamie was sitting in a boat in the bay when he released the valves on two tanks pointed rearward. Boat hardly moved. I always thought he should have positioned them below waterline for a little more exciting ride.

Accelerating a 100# steel cylinder sliding on about a 36 square inch contact patch on hard concrete apparently requires a lot less force than accelerating 800# of person, boat and cylinders trying to plow water out of the way.

I once saw some TeeVee science show where some guy put a chair on a wagon and hacked a CO2 fire extinguisher to get thrust, and it actually moved him on his cart at least out of the frame.

Or it could have been camera tricks. ;-)

Cheers! Rich

Dare i ask the price difference between "industrial" and Aircraft/Medical oxygen?

The welding stuff will cost you anywhere from 16c a cubic foot to (the sky is the limit) because it is often priced at whatever the welding shop thinks they can get.

Tractor Supply Co charges US$1.10 a cubic foot to refill a teensy 20 CF bottle and US$0.16 a cubic foot to refill a generous 251 CF bottle.

Search Term:'Oxygen Gas Contents'

I haven't bought the 'medical' grade stuff in a *long* time so I can't quote on that.

--Winston

If you have to ask, you can't afford it............... ;-)

Steve

As I recall, about 3x...

Brent wrote:

Looks like they get a ~$20 hookup fee and a few cents a foot for gas.

-- If you can solve your problem, then what is the need of worrying? If you cannot solve it, then what is the use of worrying? -- Shantideva

I wonder why it is that we allow the medical, legal, and gov't to rape us as they do...

-- If you can solve your problem, then what is the need of worrying? If you cannot solve it, then what is the use of worrying? -- Shantideva

(...)

(Tractor Supply Co Oxygen fill)

?

I scanned their FAQ and didn't see mention of a 'hookup fee'. Where did you see that, Larry?

--Winston

IANAB (bookkeeper) but I read between the lines by looking at the prices of gas by volume. ~ = approximately.

-- Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive. -- Howard Thurman

I compared prices around here (Philadelphia area) last year and the difference was about 9x for the closest tank sizes available, 3x as much gas in the smallest available industrial bottle for 1/3 the price. Of course it all comes out of the same LOX tank and is absolutely the same gas.

I did some start-up troubleshooting and testing on a relocated air separation plant a couple decades ago. The plant provided industrial, aviation and medical gas, all from the same storage tanks and all with the same purity requirements. The only significant contaminant (and the only one routinely tested for) is nitrogen, allowed at something around

1% (exact limit forgotten). The other significant components of air, mostly CO2, water and hydrocarbons, are removed in low temperature adsorbers to extremely low levels, because anything that gets through will freeze in the heat exchangers or expander and gum up the works, forcing an expensive plant shut down.

That's the same as saying that they have a $100 hookup fee but they *pay you* $3.90 a cubic foot for the privilege of giving you a free refill on your 20 cu ft bottle, yes?

Dayum. I should have been a Salesman!

:)

--Winston

In practical terms thnere is no difference.

But wait, there's more!

Fill a larger bottle and the price is cheaper. We'll give you $0.19/cf for that privilege!

-- Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive. -- Howard Thurman

Sorry - missed the "price". Answer, from negligible to considerable, depending on where you get it and in what quantities

First off

it seems some list members are pilots.

In my plane the manuals say i can hit the aviation legal Oxygen range....Barely

Its one of those things that if i had an opportunity to test i would take up the challenge to see if it was possible but practical reality says the cheap answer is to fly where its cozy and safe to breathe the air and never worry about it.

Plus the view is better than being way up high

And its more fun to fly where you can feel the bump in the air as you cross roads (and beaches are much more interesting.)

Gerry :-)} London, Canada

Hey, this is a cool group. Just found it. I'm definitely a novice metalworker, though I have an ancient lathe and make stuff on it from time to time. I hope someday to own a better one, and a vertical mill to go with it (grin).

Around here, at least (mid-state NY), the price difference between welding O2 and USP (medical) O2 is negligible for the large (200cf-ish) cylinders. It's only a few dollars more for USP O2, though I don't recall exactly how much. Aviation O2 isn't available at my local gas supply company (I asked), so I never got a price on it.

As to whether one can breathe welding/industrial O2 safely, what follows is my opinion: It depends. For scuba diving, Technical Diving International gas mixing standards call for USP or Aviation O2 to be used for mixed-gas (Nitrox and Trimix) blending because the partial pressures of any contaminating gases rise as a function of depth, exacerbating their effects. Clearly, this also applies to using pure O2 under water.

At sea level or above, depending on whatever else was in there, you're still taking a chance. For example, consider a tank that contained 100% acetylene at atmospheric pressure before being filled with O2. The usual fill pressure of 2400 PSI would yield one part in 163 (2400/14.7), or ~6,100 ppm at sea level. The OSHA exposure limit for acetylene is

1,000 ppm. Oops. (Do your own math and research the exposure limits before you breathe anything!)

For CO, 50 ppm is a problem and 70 ppm is a real problem. 6,100 ppm is obviously Right Out. Even at 10,000 feet, where if I recall correctly flight crew must use O2 after 20 minutes, that's still 70% or so of

6,100 ppm (~4,300 ppm), so aviation use would not be safe either in this case. There could be other contaminating gases I haven't thought about that might be worse than CO. And if the fill pressure is 2105 PSI, the percentages are even worse.

Now, how an O2 cylinder would wind up *full* of a bad gas, or even with a high percentage of it, before being filled with O2 is not at all clear to me. Someone would almost have to work at it! Nonetheless, safe definitely beats sorry hands down in this case, and "probably OK" means that sometimes it won't be OK. Since "not OK" can translate to "dead," I'm going to continue to buy USP O2 for breathing.

My understanding is that USP and aviation grade O2 are put in cylinders that have been purged with O2 before final filling, so the maximum levels of contaminants are quite low no matter what's in the tanks before they are purged. This is a very "practical difference" to me when the O2 will be a breathing gas, even though the source of the O2 used to fill any tank (industrial, USP, or aviation grade) is very likely to be exactly the same.