welding oxygen

[Squirrel Girl]

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...

I had no idea either, until a year or so ago.

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.

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!

[PeterVICEG]

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

[bletso]

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.

Dale

[Superlyte27]

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.

[bletso]

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

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.

[diverdarren]

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

[Superlyte27]

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.

[ScubaRob]

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.