This is probably going to sound dumb but, what is the difference between the o2 used to fill welding tanks and medical grade o2?
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This is probably going to sound dumb but, what is the difference between the o2 used to fill welding tanks and medical grade o2?
No difference at all, but how they clean the tanks is a different matter. Medical O2 (in the US anyway) requires emptying the tank under vacuum, then refilling with O2. For welding tanks, they just refill them as-is. The problem is sometimes acetylene gets in the tanks, if the previous user left toe O2 run out, before the acetylene.Quote:
Originally Posted by phillip1
Another option is Aviation O2. They are emptied, but not under vacuum, and are much less likely to have any strange gas in the tanks.
purity and contaminants.
Medical grade has been tested for CO and CO2 and only allows a certain ppm, welding (industrial) grade may or may not have depending on where you get it and what you ask for. Some states regulate Medical grade (like Va) so you can get industrial grade that has been tested to the same standards as medical.
there are others, but that is what i what i can recall off the top of my head.
Scott
It's a matter of purity. Welding oxygen can be as low as 93% pure, depending on application. There's 99.9 (aviator), 99.98, 99.99, and 99.999..oh and 99.6 too. I also think the water content differs depending on grade.... Other's probably know more about the details and just how pure is necessary for breathing. We use the ultra high purity (UHP) which is the 99.99% and dry. However, here's a statement by a local supplier:
"There are four kinds of oxygen that are merchandised or sold to users; Aviation, Medical, Welding and Research. There is a ongoing controversy if there is any difference between the different types. Oxygen gas is produced from the boiling off of liquid oxygen. It would appear that the oxygen is therefor the same. Where we obtain oxygen, all the different types of oxygen are supplied from the same manifold system. Then someone says that medical oxygen has more moisture in it. That is partly true. The oxygen going to a hospital bed is plain oxygen that comes from liquid oxygen. At the bed location, there is a unit on the wall that adds moisture. At this moment we now have medical oxygen. If the oxygen is in a pressure vessel or in a manifold system (like inside a hospital) then it is regular oxygen. The cost of medical or welding oxygen is normally much less than the oxygen you get at an airport.
Also of interest, we have been told by the suppliers of welding oxygen, the purity level required for welding and cutting purposes is more critical than for breathing.
The bottom line about the different types of oxygen is in the insurance liability of the oxygen supplier. The gas is the same but the insurance liability is different."
skip
ahh, forgot liability. If you are a dive shop or charging people for fills, you want the gas that comes tested and with certifications of purity from the supplier, so if you get sued you can show that the gas was lab tested, if you are home brewing for personal use, then it really doesnt matter, just as long as you are ok with the gas you choose.
Cost is another thing, you will pay more for the 99.99% than you will for the 99.98%. Is the additional 0.01% worth 3-5 cents cu/ft?
The hospitals here get o2 from the very same place that sells to the welders, a kind of "clean" and "organized" looking setup (for here that is) in Puerto Plata but still when I see the all the area hospital tanks (they have each hospital logo) to be filled right next to the welding tanks it makes me wonder.
i guess it is pretty much the same thing then.
Only if the tanks are clean!!Quote:
Originally Posted by phillip1
I have been using welding O2 no issues. Here in MN you need a prescription for medical O2 as I don't have one just use the welding. The supplier also told me the welding was exactly the same as medical, coming for the same place minus the paper trail. Never have asked about aviator. One time while picking up O2 and Helium I made the mistake of saying I was using it to breath. The guy more or less freaked out, after he settled done I say to him "next time I guess I shouldn't say anything about breathing it" his comment was "that would be a good idea" Okay then :-)
Al
Right - that's the other side of the liability issue. They may be the same gasses but the paper trail is important if they know or reasonably suspect you are using He or O2 for breathng. If you don't tell them, then they can honestly claim they had no idea you, the dumb ass you died, were using the gas for breathing and they can assure all involved including your widow and her hearse chasing attorney that had they known, they would not have sold you welding gas.Quote:
Originally Posted by ScubaAl
you could get a diving wife...Quote:
Originally Posted by DA Aquamaster
Dive safe,
Celia
Forrest, pleast tell me you don't really believe this? Perhaps Raphael will chime in to tell us what happens if you try mixing acetylene and oxygen in a tank like that...Quote:
Originally Posted by FW
Just about every torch I've seen has check valves to prevent this.Quote:
Originally Posted by aainslie
Forrest is right about dirty tanks, however. I've seen plenty of industrial O2 tanks that were run flat empty.
Is there another kind?Quote:
Originally Posted by amphipod06
Mike
A non-diving ex-wife?Quote:
Originally Posted by MORGAN
Oh, me, always coming late to the party. I just got around to reading this thread. Not surprisingly, ya'll came up with my answer before I got here:
PriceQuote:
Originally Posted by phillip1
That was my thought. Hokey smokes! Literally! Ker... BLOO-ey!Quote:
Originally Posted by aainslie
I've been a welder for 40 years. When I first started tourchs didn't have checks or back flash valves, but they are required now. Not all but most gas houses vacuum scavage all O2 tanks and fill welding and medical together. They only keep batch numbers for the medical tanksbut are filled with the same O2. Avaition O2 is drier then breathing O2. I've used it for years, that being said I wouldn't tell anyone to do it.
Jack
Believe it or not, we get a couple of acetylene contaminated cylinders in the hydro station a month. Oh, BTW, they can go whoosh like a jet engine if you try to clean them incorrectly.Quote:
Originally Posted by aainslie
They will not auto-ignite, but put a small spark and it can be interesting. We charge the customer $50.00 each to decontaminate them. It's kind of an incentive for him to find out which of his clients are doing it.
Dale
On slow days we'd take a pie tin, put a small hole in the bottom of it and invert it on the floor then fill it with acetylene. Add a small spark and you get a wonderful boom!. Great fun, but a little beer always helps, especially for the guy who lights it.Quote:
Originally Posted by bletso
See bletso's post. It is harder now that it once was, since most new rigs have check valves.Quote:
Originally Posted by aainslie
We used to squirt some acetylene into a beer can, perch it inverted on a workbench with the opening over the edge, and ignite it to see it go poof. Once I got the clever idea of adding a little oxygen. Must have got the mix just right, as with a loud bang the beer can hit the ceiling hard enough to dent it. The can was bulged, and the edge of the workbench was scorched. This was back in the days of substantial beer cans - a modern thin aluminum one would probably have ruptured. Wait - I've got a beer can right here! Maybe I'll test it!Quote:
Originally Posted by DA Aquamaster
Mike
Years ago, I took a torch, got the mix just right, extinguished the torch and filled balloons with the mix. Tie a kerosene soaked sting to it as a fuse and stand WAY WAY back. It would easily lauch a galvanized 40 gallon garbage can way into the air if it was placed upside down on the balloon. If you though a beer can full was loud, the balloon is like a stick of dynamite. DO NOT TRY THIS AT HOME!!
John
Hmmm...this could be a great way to wake the neighbors if you air launch the Oxy/acetylene filled balloon and fuse under a few helium filled balloons...Quote:
Originally Posted by giles45shop
Once we inflated a 40 gallon trash bag with acetylene and closed it with a rubber band. We tied a long string to it, and set it out in the field behind the shop. Then we lit a candle and set it on the ground, stood way back, and pulled the string to bring the trash bag into contact with the candle. The resulting thunderclap made us abandon our next plan of adding oxygen to the mix.
Bored guys and inflammable gases - good times!
Mike
All we needed was a little dry ice and some empty 2-liter Coke bottles.Quote:
Originally Posted by MORGAN
Quote:
Originally Posted by MORGAN
:rollguy ^ story of my life!Quote:
Originally Posted by jlillest
Wow. I had no idea. I stand corrected - sorry Forrest!!Quote:
Originally Posted by bletso
Pretty cool,we did the same thing with hydrogen once.Quote:
Originally Posted by MORGAN
I had no idea either, until a year or so ago.Quote:
Originally Posted by aainslie
Quote:
Originally Posted by aainslie
I wonder how often explosions occurred? You'd need a spark, but it still seems mighty dangerous! I don't recall hearing about such explosions in the news, but then i don't really hear about things like dive shop bank explosions anywhere but tech diving fora (like here).Quote:
Originally Posted by FW
You would need the mix in the tank to be right for an explosion. The ratio won't always support combustion. With the check valves, the occurances have been greatly reduced in modern times. There were some accidents before the law was passed, though.Quote:
Originally Posted by Squirrel Girl
Quote:
Originally Posted by aainslie
Quote:
Originally Posted by FW
Certainly gas mixture do make a difference! But on the other hand, whew! How 'bout a tiny bit of oil in a hyperbaric chamber? I'm guessing that there were enough problems (if not explosions) to make the changes to exclude the gas contamination. But I still don't recall vast numbers of explosions in the news!Quote:
Originally Posted by FW
http://www.deepcaves.net/smilies/snowglobe.gif
I am a little late to this thread, but... Carbide was long the light of choice for any decent cave trip up here. Carbide plus water makes acetylene which is notoriously explosive at very low pressure. When you reload, the spent carbide can still be active. I once threw down a side bag with "spent" carbide in it, only to have it explode! The seams were blown open and the straps torn off.
Carbide in tanks is not stored as a gas. It is in solution. I find it hard to believe that there would be much more than a trace of said gas in a o2 tank. Of course the acceptable partial pressure of combustable gases in O2 would be......?
Peter
Hard to believe or not I have found them with at the least 5-10 psi of acetylene in them(rare). Usually it is just a positive pressure of acetylene, more acetylene then O2 and definitely very ignitable.Quote:
Originally Posted by PeterVICEG
Dale
I've been thinking of this thread for quite a while, and my cutting rig is/was pretty standard. I simply see no way for Acetylene to enter into the O2 bottle. It's completely separate bottles, guages, regulators, lines, valves, etc. The only place where the two lines meet is just before the tip past two check valves. The only way I can see Acetylene enter the O2 line is if the O2 bottle was completely empty, the check valves were bad and the tip of the torch (all 7-10ish holes) was plugged up.
I think you got better chance of blowing yourself up igniting a fart.
Cool, believe what you want. I run a hydro business for industrial gas cylinders and as I have stated already it happens and all to frequently whatever the modality for the cross contamination.
BTW, that is one reason the fill plants do a sniff test of their cylinders. They know weird things happen and they want to avoid liability. Talk about weird, how about someone with too much time on their hands stuffing a roll of toilet paper in a medical B cylinder! Sounds funny eh, well if the fill was too fast the cylinder could have gone off by adiabatic compression and an inattentive fill operator. A B cyl is a small medical 3 3/4 X 12". See attached.
One of my men got hurt whilst taking a whip to wash out one of these non-existent cylinder problems and was digging metal pieces out of his hands for a week. We found the only way to do it correctly was to completely fill the cylinder with water and then begin the wash. Purging with N2 or other gas just doesn't do it well enough.
Dale
Quote:
Originally Posted by Superlyte27
Before any more of you arm chair geniuses attempt to cast any more doubt on what Dale is saying,know this; Dale is a tech instructor, a nitrox and trimix blending instructor, as well as a rebreather builder,a long time full cave diver and personal friend of mine who I know not to be a liar. If Dale said it, you can be sure that it happened just the way he said it did. Darren
I respect his opinion as much as I respect yours since I know neither of you. :)
I wasn't casting doubt, and those qualifications really don't mount to a hill of beans to me. While I'm sure that ANYTHING is possible, that still doesn't make it likely. There are far worse and frequent dangers out there.
I'm not a tech instructor (yet). I don't build rebreathers, but I have been a long time cave diver, commercial diver, and someone's friend. I've been mixing Heliox, Trimix and Nitrox for more than 15 years. I've managed chambers in the gulf and beyond. I've managed gas racks for divers both shallow and deep with both Air and Heliox. I've used anywhere from 3 to 20 bottles per week of O2 supplying divers from every depth imagineable for more than a decade, and by and large, the O2 we are using is the same O2 we are burning with.
Is it possible? Yup, sure it is. Is it likely? I haven't come across it in um...... 300+ bottles per year for the past decade. There are worse things to fear.
When I was buying O2 it was only $24 for a full tank of Aviators O2. How much could you actually save by buying welding grade instead? Even if the welder's grade was free I would pay $24 for the piece of mind that it's actually breathable.