o2 explosion

[Burntchef]

http://www.wral.com/news/local/story/8875309/

pretty sad story, he is very lucky to even be alive.

[BDub]

I saw this the other day.

Does anyone know if it was really oxygen, or the typical media practice of calling a scuba tank an oxygen tank?

[CaptnJack]

It was an oxygen deco bottle. Its pretty clear from the conflagration that combustion in the garage was massively accelerated. Its not clear whether the valve was knocked off or if the tank split around the sidewall from another cause.
http://thedecostop.com/forums/showthread.php?t=45973
http://www.wral.com/news/local/story/8875309/

[Sounder]

It was definitely an O2 deco bottle - confirmed by someone I know who happened to be on scene. Scary stuff. My weekend's project is securing my "stable" of tanks and I will be exercising some extra caution when moving bottles from now on. Seriously scary stuff.

[kdupreez]

Thats a really bizarre accident.. I have never heard of or never seen an O2 tank just "explode" when knocked over.. there is zero reason for it to..

Only thing that will make an AL tank explode like that is severe over pressurization or very high impact that puncture or ruptures it.. Filling too fast causing heat of compression or particle impingement to ignite contaminants that leads to a possible internal deflagration, some other extreme heat to break down the metal or good old metal fatigue over time (aka 6351-T6 aluminum alloy scuba tanks), but then it was a ticking time bomb to begin with..

As you all probably know, Oxygen doesnt just "explode" by itself.. you can blow a match out with O2, its non flammable.. you have to provide an ignition source and fuel.. O2 is needed to complete the fire triangle and off course pure O2 is just a super accelerator..

unless there was a pretty high impact directly on the valve that bent it enough for O2 to come rushing out the valve at a fast enough speed to cause heat of friction high enough to ignite the actual aluminum or brass valve, it aint gonna explode or even burn.

O2 Leaving a tank at a high rate actually cools it down significantly.. Even if your burst disk on an O2 cylinder had to go, it will probably freeze the outside of the tank and empty out before it will explode. Unless again, its a rupture at the tank neck and its leaving so fast the friction ignites the actual metal..

Looking at the pics of the tank, it looks like the valve is rather bent and the Viton O-ring is protruding at the neck plus the the tank looks pretty burnt up around the Neck area.. This wont happen "after" it exploded.. Even the red "dust cap" is melted all over the valve..



But the valve and tank neck doesnt look melted enough to produce the heat needed to break down the AL and make it rupture? If it did, this didnt happen within seconds and the tank must have dropped from quite a height, straigt on the valve..

My guess would be this was a fatigued and old tank that had an existing condition and it was just a matter of time..

Tanks dont just "explode" - pretty freakish accident!

thoughts go out to him for a speedy recovery and to his family for the helluva time restoring the property!!

[Kees]

That picture was somewhat confusing to me until I watched the video. Here's another screen capture that shows a bit more of the tank:

[ljjames]

the time between fire/explode/meltdown/tremendous damage in the garage would have been milliseconds. if you've seen the video's of O2 lines igniting and burning, they had to show them in slow motion so we could see what happened.

as is discussed on the decostop thread, it sounds like it is quite possible for a tank to fall and have the outcome complete the 'fire triangle'. this could of course be made easier by crappy alloy. fall causes crack,crack causes high pressure leak, high pressure leak cause fire/explosion, internal fire/explosion cause superheated high pressure gas to blow out the thin side wall of tank that may or may not have been a weak alloy, all happens so fast hard to tell what happened when.

Call me a chicken, but i've always stored my O2 tanks laying down with the valve [knob] facing the wall... i was taught to do that by my gas blending instructor in 93, and i've just always done it that way. (those who have seen the garage have probably wondered why there was a little pile of O2 bottles lying down against a wall). I was taught that even cracking the valve really fast (like if you drop something on it or kick it or what not) with that not so compatible seat in there you can cause a flash point due to the friction of the gas. this is also why i was told that the old Scubapro valves that were just 'on/of' were not usable with O2 EVER, because the hammer effect of the quickly opening/closing valve was a huge risk for heat production and flash fire.

so taking that into consideration, all that maybe had to happen was the tank fell and hit its valve and the knob turned just enough to crack open very quickly... obviously luck was not on anyones side that day no matter why it happened, and its horribly sad to think about loosing ones arm or even ones life to something so freakishly accidental, but scary to think that we have similar tanks in our midst.

i'm sure that they'll do a thorough analysis... if its anything like what was done for the luraville accident...

http://www.phmsa.dot.gov/staticfiles/PH ... _17_06.pdf

[CaptnJack]

Been thinking about this and my hypothesis:

knob open knocked in fall
vinyl dust cap ignites
fire flashes back into AL tank
tank ruptures in sidewall (weakest part)

[ljjames]

tank gets knocked over
knob opens suddenly slightly
adiabatic compression heating ignites seat/hydrocarbon deposits on seat
flashback
aluminum -> O2 -> fire -> heat
tank wall instantly crystalizes (or it was weak alloy)
boom.

i think if the vinyl caught fire (and i considered this too) it should have been blackened and incinerated completely (considering it had O2 for fuel) as opposed to just supermelty. If tank valve is opened a lot the vinyl caps usually just pop off. this one (if it was a cap an not just red electrical tape) melted away, but in a weird pattern if the tank was laying on it side (its below the valve and wrapped around the burst disk), which is what made me think vinyl tape.

Been thinking about this and my hypothesis:

knob open knocked in fall
vinyl dust cap ignites
fire flashes back into AL tank
tank ruptures in sidewall (weakest part)

[kdupreez]

I cant see how a fire can flash back into an O2 tank? there's no fuel?

l was puzzled at what will cause enough pressure for the walls to rupture.. I thought the valve will burn off and the tank will go flying around.. Looking at that valve closely you can actually see valve slightly melted at the valve opening!

I've seen whip ends spontaneously combust before (on video) and burning like a mofo when O2 tanks were openend too fast and lines are empty and downstream valves are closed.. that heat of compression on short whip ends can reach about 1500 degrees F in milliseconds.. and cause the whip ends to spontaneously combust.. even teflon lined stainless steel braided hoses make a good fuel at 1500F !

So that nylon seat is a very good possibility! if a valve is very suddenly opened (like in a fall) the friction of rushing air over a worn nylon hp seat will ignite it easy and the rest of the valve internals will follow raising the temperature of the tank and gas so rapidly the gas expands so much, the tanks ruptures!

this looks eerily similar:
http://www.scubatube.net/play.php?vid=85

Extreme O2 pressure and high flow creates lots'o heat.. big heat make tanks go BANG!

moral of the story.. I agree.. store tanks laying down or secure them! and SLOW the roll when handling O2.. thats like step 1 in gas blending..

Scary stuff!!

[CaptnJack]

We'll probaly never know, damn gas is like a random number generator.

Its unclear whether he bumped the tank with his body or with his car, he was returning from a sport game somewhere.

[Grateful Diver]

I don't think that's an AL tank ... look at the curled-up bit of sidewall in Kees picture above.

How many of you have seen what a cut-away AL80 looks like? The walls are MUCH thicker than that. I think that's a steel tank ...

... Bob (Grateful Diver)

[ljjames]

neck looks like an AL to me... walls can 'tear' at a diagonal (as seen in the Luraville blow out picts) Also i thought the guys friend/dive buddy said AL deco bottle somewhere (not the news).

Regarding the incident itself, we'll find out more i'm sure when the victim gives his friend go ahead to post more... i get impression he's a bit busy now recovering from a forearm amputation. Although this is an accident thread, we need to keep in mind this is about a person who got very very hurt. if you watch the video, the damage of the garage is just profound. The car looks more like it was already parked but who knows...

[airsix]

This story is forking in all directions. I'm with Bob. That sure looks like a steel cylinder. No aluminum bottle has walls that thin. They would be at least 1/2" thick in that area. I could be completely wrong, but it sure looks like steel to me and I've been up close to cutaways of both. Like Bob observed, aluminum is not very plastic. It would fracture rather than curl like is seen in the photo. Everybody is saying there was a plastic/vinyl valve cover in place, and I can see evidence of that. At the same time it is claimed to have been hooked up to a fill whip. Well which is it? Can't be both.

While we're throwing out wild theories here's mine. The bottle was not hooked up to a fill whip (it was capped). It was upright between the car and the garage wall. Squeezing past the bottle rolled the valve on rapidly causing combustion to occur in the valve. I don't think a fall had anything to do with it and I think the o-ring extrusion and apparent bent nature of the valve are simply the result of rapid pressure increase, not impact with the floor. This concludes my WAG.

*Edited to add: I could be completely off on the steel vs aluminum. Camera angle could be hiding the wall thickness. Laura is right about the neck. I'm still on the fence.

[CaptnJack]

This story is forking in all directions. I'm with Bob. That sure looks like a steel cylinder. No aluminum bottle has walls that thin. They would be at least 1/2" thick in that area. I could be completely wrong, but it sure looks like steel to me and I've been up close to cutaways of both. Like Bob observed, aluminum is not very plastic. It would fracture rather than curl like is seen in the photo. Everybody is saying there was a plastic/vinyl valve cover in place, and I can see evidence of that. At the same time it is claimed to have been hooked up to a fill whip. Well which is it? Can't be both.

While we're throwing out wild theories here's mine. The bottle was not hooked up to a fill whip (it was capped). It was upright between the car and the garage wall. Squeezing past the bottle rolled the valve on rapidly causing combustion to occur in the valve. I don't think a fall had anything to do with it and I think the o-ring extrusion and apparent bent nature of the valve are simply the result of rapid pressure increase, not impact with the floor. This concludes my WAG.

*Edited to add: I could be completely off on the steel vs aluminum. Camera angle could be hiding the wall thickness. Laura is right about the neck. I'm still on the fence.

This is not the Luraville, FL fatality incident. That keeps coming up her and on TDS for some reason, that old incident is where the tank was being filled.

This tank was in a garage in NC and "bumped" by the owner or the owners car when he came home. The neck of the tank is a machined Ali neck shape, not steel at all. Steel tanks are not machined like that. On the first "88" hydro stamp there is the Xmas tree shape that signifies it was made by Luxfer as well. So it was a AL6351 cylinder, which may partially account for the shrapnel pattern when it exploded.

The wall thickness and "curls" are a function of the camera angles and however it got torn in the explosion.

[airsix]

Thank you, Richard.

[Tangfish]

Wow, freaky stuff. I'm going outside to lay my tanks down with Valves pointed at the wall!

[ljjames]

i think the Luraville explosion came up because it had excellent pictures and fascinating data followup of a tank explosion. Also because in the TDS thread there was some confusion regarding bumped vs. on a fill whip. Someone posted the report, and therefor a bunch of us that are driven by morbid curiosity read it. In that report they mention valve seats and bleed valves and things like that (and Dip tubes for that matter) as ignition points, and why (in the luraville case) the valve seat was not the answer... but the discussion of valve seats and material compatibility and so forth makes sense, combine that with some of the incinerated valve seat threads on TDS, combine it with what was taught in gas blending class and the data can be extrapolated by people with fertile imaginations and without anything better to do (like me at the time of reading it) and voila! mix and match thread!

[ljjames]

Wow, freaky stuff. I'm going outside to lay my tanks down with Valves pointed at the wall!

ya, i'm also really careful with O2 tanks (and their valves) in my car when i'm throwing gear around and driving and such... I worry about cracking an O2 valve too fast when throwing something on it, or if it shifts too fast whilst starting stopping and gets bumped. How many times have you had a valve open and had to dig around and close it? (I know i've done it more than once)

(the positive power of negative thinking... I realize it may be over thinking, but at least then i don't worry about it)

[Gill Envy]

Craaaap! I doubt i'm the only one wondering what year, what alloy and does it match anything in my basement?... was it out of vip/hydro... I was always told that the DOT intended these tanks to be able to handle falling off a truck on the highway at high speeds without rupture... thus the DOT requirements.

just removed the o2 bank bottles out of the room underneath my daughters bedroom and placed them on their side (good suggestion Laura!), opposite to where we sleep... just as a precaution. It's hard not to feel a little paranoid. Time to reread the oxyhackers.

I feel sorry for the guy who lost his arm, that just shouldn't happen!

g

[Nwbrewer]

Wow, freaky stuff. I'm going outside to lay my tanks down with Valves pointed at the wall!

ya, i'm also really careful with O2 tanks (and their valves) in my car when i'm throwing gear around and driving and such... I worry about cracking an O2 valve too fast when throwing something on it, or if it shifts too fast whilst starting stopping and gets bumped. How many times have you had a valve open and had to dig around and close it? (I know i've done it more than once)

(the positive power of negative thinking... I realize it may be over thinking, but at least then i don't worry about it)

Maybe those SS DIN plugs would be a good idea on O2 tanks as well as HE. I realize most people use them so they don't loose expensive fills, and O2 isn't that expensive, but it sounds like the doctor bills from a quick roll off might be.

[CaptnJack]

Wow, freaky stuff. I'm going outside to lay my tanks down with Valves pointed at the wall!

ya, i'm also really careful with O2 tanks (and their valves) in my car when i'm throwing gear around and driving and such... I worry about cracking an O2 valve too fast when throwing something on it, or if it shifts too fast whilst starting stopping and gets bumped. How many times have you had a valve open and had to dig around and close it? (I know i've done it more than once)

(the positive power of negative thinking... I realize it may be over thinking, but at least then i don't worry about it)

Maybe those SS DIN plugs would be a good idea on O2 tanks as well as HE. I realize most people use them so they don't loose expensive fills, and O2 isn't that expensive, but it sounds like the doctor bills from a quick roll off might be.

Maybe, but you're stuck opening the pressurized plug with a big wrench. A hydro station guy took the jammed valve off an O2 tank that way once and lost his hand in the explosion.

O2 + massive amounts of friction + oring or cylinder material fuel = bang

[ljjames]

my thought exactly... (what richard said)

[Nwbrewer]

Excellent point. On my way back to the peanut gallery.

[Burntchef]

i allways keep my o2 reg on my bottle period. if it bumps and pressurizes i can depressurize it slowly.

thoughts?