Deco Cylinder Mishap

[Lead_carrier]

Please keep this A&I thread as a way for all of us to learn and prevent another catastrophe.

Let's examine the possibilities of what could have happened and prevention:
1-gear failure? valve damage or handle jarred during loading?
2-truck failure? It's been mentioned David had ongoing problems with systems in the truck. I personally don't belive this caused the fire but may have contributed.
3-dive knowledge? I personally find this doubtful in this case, as those who know him, know he was consciousnesses about training, and learning as much as he could about any subject.
4-diver error? Possibly, fatigue, rushing, multi-tasking.What we need to ask ourselves is: "Are we diligent about handling any and all cylinders each time we transport them?" I know when I'm tired or in a hurry, I'm less careful, less observant and I can become complacent in my methods when I'm loading/unloading my 20th tank of the day. I am thinking carefully how I transport gear especially deco cylinders in my SUV...

With the reports of an explosion, could the burst disk have been plugged our doubled. I'm not trying to point fingers or start anything but on other threads we've discussed the pros/cons of doubling or even plugging burst disc. I know this is a fairly common practice for a lot of cave and tech divers.

 

[mselenaous]

Another photo:

 

[Jim Lapenta]

With the reports of an explosion, could the burst disk have been plugged our doubled. I'm not trying to point fingers or start anything but on other threads we've discussed the pros/cons of doubling or even plugging burst disc. I know this is a fairly common practice for a lot of cave and tech divers.

While it may be "common" to double up on discs it is not done on deco cylinders. At least I have never heard of it being done on anything but backgas tanks. The PPO2 levels are such that only a fool would double up a disc on an oxygen cylinder. Remeber if it was a deco bottle with 100% O2 it would take the tiniest spark or just coming in contact at pressure with a small amount of a hydrocarbon to turn that bottle into an out of control torch.

Just as an aside, I work in a metal fab shop and can tell you an O2 fire like that would also be hot enough to ignite the cylinder itself if it was an aluminum one. You'd have a bitch of time getting it out as well. I don't know why there is no regulation calling for a combustible metals rated fire extinguisher in shops doing partial pressure blending. A CO2 or foam one ain't gonna cut it.

 

[ianr33]

I've thought of another possibility which is pretty damn scary.

O2 cylinder in the cab,valve cracked open building up a high O2% inside the truck.All it might need is one spark from static electricity to set that off.(Or a spark from any of the electronics in the truck. That's what happened to Apollo1 )


I'm going to make a point to ALWAYS have DIN plugs in my O2 bottles. That way if the valve gets accidentally opened (which is really easy to do with a truck full of gear) the O2 will not leak out.

 

[Hatul]

We had an explosion of an O2 cylinder in San Diego several years ago, but the mechanism here sounds different. In the San Diego accident the diver had a titanium reg on the tank, and it was believed when the valve was opened adiabatic heating caused the titanium to burn.

 

[JahJahwarrior]

I think DA aquamaster pointed out already that having a din plug without a pressure release could be dangerous. I think leaving the reg on should be pretty safe: contains an o2 leak but also let's you vent leaked o2 safely instead of creating heat while unbolting the din plug.


The question I keep expecting to see is, does Dave use any 6351 tanks? Does he o2 clean himself? Any idea when this tank was last cleaned?

I have o2 bottles that aren't cleaned in between hydros, wondering it I should devote a weekend to cleaning valves soon...

 

[Wookie]

There is no reason to double up the burst disc on deco bottles for a couple of reasons. First off, you aren't pumping more than 3000 PSI into a deco cylinder anyway. Lots of shops stop at 2250. Second, if the burst disc blows while diving, you go into a lost gas scenario which you had planned for before going diving.

Jim, the O2 doesn't have to come in contact with a hydrocarbon, that is usually at high pressures. The O2 could have been in the truck where fuzzy carpet and "tinder", if you will are present. If there was an ignition source (cell phone ringing, turn the key, open the door and light on) the tinder doesn't explode, but it burns so quickly that you or I couldn't tell the difference. Kind of like a back draft or a flash over in a burning building.

Ian, you need to think long and hard before you put DIN plugs in your valves. If in fact they do pressurize, when you go to take the plug out under pressure, the heat of friction and any little brass metal shaving under high PPO2 will cause the shaving to burn resulting in the same scenario. I think that the chance of that happening is way higher than a roll off in the cab of the truck. Of course, I don't keep deco cylinders in the cab of the truck, I let them get all beat to hell in the bed.

 

[Wookie]

The question I keep expecting to see is, does Dave use any 6351 tanks?

He's been on the Spree a few times in different capacities. He always had relatively new Catalina 40's from my memory. RN may remember something different, he's seen David since I have.

 

[mselenaous]

The AL40 cylinder I saw was relatively new (only the original hydro stamp on it, didn't pay that close attention to recall the date). In the past few months, David had completed Full Cave certification in Mexico and in December Side-Mount and DPV training in NoFL Cave Country.

 

[fdog]

I've thought of another possibility which is pretty damn scary.

O2 cylinder in the cab,valve cracked open building up a high O2% inside the truck.All it might need is one spark from static electricity to set that off.

I'm going to make a point to ALWAYS have DIN plugs in my O2 bottles. That way if the valve gets accidentally opened (which is really easy to do with a truck full of gear) the O2 will not leak out.

This has been exactly the chain of events I've been ruminating over; and the photos only reinforce that.

I've thought of another possibility which is pretty damn scary.

O2 cylinder in the cab,valve cracked open building up a high O2% inside the truck.All it might need is one spark from static electricity to set that off.

I'm going to make a point to ALWAYS have DIN plugs in my O2 bottles. That way if the valve gets accidentally opened (which is really easy to do with a truck full of gear) the O2 will not leak out.

Ian, I can certainly understand why you'd be thinking along those lines. Up until a year or so ago, I'd have been right there with you. Do me a favor, and tell me if I'm off base with these thoughts...?

I now do not place DIN plugs into deco cylinders of 100%; I am worried about wrenching off a plug if it became charged. I will cheerfully wrench off a DIN plug anytime for bottom gases or even 32%, but I worry that with 100% O2, the friction may cause an explosion. The mechanism of removing a charged DIN plug seems entirely to close to what caused this explosion.

I'll transport 100% either with a reg in place, or, a "donut" (to keep the valve from deforming if smacked by another tank).


Everything else I own has a DIN plug except O2.

All the best, James