Deco Cylinder Mishap

[Christi]

I have been diving with David. I have seen his equipment. I believe this was an unfortunate combination of simple items that lead to a disaster. Any of which could happen to the best diver again. I believe this was a case of the 100% leaking into his cab(closed space) providing a highly oxygenated environment. The truck had many known issues(read: lemon or continual issues) and maybe some unknown issues. Add to this a parking garage with who know what fumes/gasses. A flash fire ensues in a closed small environment acting like a bomb. The fire gets hot enough to setoff another 32% or maybe 50% bottle. Simply a bad combination and bad timing and another good diver is suffering.

We joked at the dive show about being twinkies wearing the same shirt from Edd's shop. We had a lot of the same interests. It just doesn't seem real that this happened to him.

Cavemn - one of the first things that came to my mind as well was an electrical short of some kind with his truck. Since the day I've known him in early 2010 very early in his diving career - he has had ongoing electrical issues with his truck - I hope that that will be checked out!!!! I don't believe David did anything to cause or precipitate this - he is one of the most conscientious people I know with regards to his gear, training and safety re same! Godspeed David!!!!

 

[DA Aquamaster]

But,the volume of O2 contained between the valve and the end of the DIN plug will be very small. I'm going to start a new thread on this as i think it's important.

It doesn't really matter. Valves are a bigger O2 clean issue than the tank, as the tank is not really exposed to potential ignition sources.

The valve is a different matter and the threads for the DIN connection are guarenteed not to be O2 clean less than 5 minutes after the valve leave the clean room. The average deco bottle will have threads liberally crusted with potential fuel. Add the friction of a DIN plug being screwed out under pressure and you have fuel, O2 under pressure and now an ignition sources. It's true there is not much O2 to burn, at least on the downstream side of the seat, but all you need is enough fuel and O2 to burn through the seat and you suddenly have a whole lot of O2 at tank pressure feeding the fire, a fire potentially hot enough to start using the metal in the valve and tank as fuel.


Will a flash fire in the downstream space between valve and DIN plug always be enough to light up the seat? Probably not, but it only takes once and I don't want to be around when/if that happens.

----


As an aside, a tech working on a medical O2 tank with a broken valve managed to blow off most of his right hand. Since the valve would not open and the tank was full, he decided to use a wrench to screw the valve out of the tank far enough to start a leak to release pressure. I'm not sure to what end, as salvaging the tank would be doubtful after you get done galling the threads removing the valve under pressure. But in any event it was a moot point as the friction started a fire (for all practical purposes an explosion) in the tank with really bad results for the tech.

It's a little different as the threads are in the tank, and the O2 is right there, but the ignition process would be exactly the same removing a DIN plug under pressure - the only difference is you would be taking bets on whether or not you've got enough O2 and fuel there to involve the contents of the tank in the resulting fire.

 

[cavemn]

Here's an update

The latest update on my friend David, from his fiance Monica:
David is doing awesome!!!! His tubes are out. He is drinking on his own.....and of course he is talking! He said he could see pretty good. His eye pressure is good. He is on less medication...he really is doing great!
THANK YOU GOD and everyone who prayed for David.

 

[falcon125]

Is there a certification required for using 100% oxygen?

 

[Christi]

EXCELLENT news! THAT is the David I know! Keep fighting and stay strong David!!!!! Thank you for the update cavemn!

 

[ianr33]

Is there a certification required for using 100% oxygen?

Yes, Advanced Nitrox course gets you a card good for 100% O2

Regular Nitrox course only gets you to 40%.

 

[Hetland]

Is there a certification required for using 100% oxygen?

Advanced Nitrox (for anything between 41% and 100%). The course is usually taken at the same time as Decompression Procedures.

 

[parrotheaddiver]

thanks for the update...and so glad it its good news!!!

 

[GlassBender]

Advanced Nitrox (for anything between 41% and 100%). The course is usually taken at the same time as Decompression Procedures.

With PADI, it came with TEC45 certification.

 

[Hatul]

...

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.

About using the plugs on DIN valves: the XSScuba convertible valves have a small pressure relief hole in the side. With the plug tight and the valve open the gas escapes through this vent and you hear a loud hiss. It also limits the rate of loss of gas. So for this particular valve using the DIN plug would help to pick up a leak and to limit the rate of leak.

All three of my tanks have the valves with the side vent.