737 destroyed by O2 explosion

[abnfrog]

I am just at fault as a bunch of older ccr divers sitting on the back of the boat cracking on the o2 ..till I heard of a girl doing the same and burning down her ccr , and then ( 20 years ago) the light turned on , treat it like you teach it assh&%le ........now I do

 

[rsingler]

Non-problem? I would disagree.
Rare, yes.
But the key difference between Scuba and CGA 540 oxygen valves is the engineering to remove sharp corners and bends that promote impact ignition. Design is why the other valves do so much better. And yes, cleanliness. But there's a reason why no scuba valve is CGA rated for high pressure 100% oxygen service, even though we use them that way. And even if the valve were perfect, where does it go next? Into a complex labyrinth that accentuates the adiabatic heating issue.
So if we're stuck with a twisty-turny gas path for scuba, at least we can use a valve design that opens ultra slowly.
It's worth the extra $80 to me, for one or two valves. To each his own, unless you're on my boat and you don't choose the extra safety margin.

 

[abnfrog]

those valves were not around when I first started with ccr , actually it was a ybod that caught fire maybe that's why they changed valves , I remember talking to peter ready way back when I was at the factory , I asked him why he didn't use a mk 20 ultra light on the prism he laughed and said they tried one ...it didn't like the 100 % o2 so the mechanisms were being looked at even then ......as far as diving on your boat .......your boat ..your rules

 

[broncobowsher]

I remember that picture of the club dive boat that Phi Le was on and posted the writeup of the accident on The Deco Stop.
Phi was a cave buddy of mine back when we were members of Odin Tech Divers around 2000.

Michael

Went digging around the Deco stop, didn't find the thread. Have a link?

 

[bletso]

Non-problem? I would disagree.
Rare, yes.
But the key difference between Scuba and CGA 540 oxygen valves is the engineering to remove sharp corners and bends that promote impact ignition. Design is why the other valves do so much better. And yes, cleanliness. But there's a reason why no scuba valve is CGA rated for high pressure 100% oxygen service, even though we use them that way. And even if the valve were perfect, where does it go next? Into a complex labyrinth that accentuates the adiabatic heating issue.
So if we're stuck with a twisty-turny gas path for scuba, at least we can use a valve design that opens ultra slowly.
It's worth the extra $80 to me, for one or two valves. To each his own, unless you're on my boat and you don't choose the extra safety margin.

I have disassembled many industrial and medical valves as well as scuba. Heck, some of the industrial valves use the same seats! The biggest difference is that some scuba valves use seat material which is incompatible with O2. I have attached a pic of one. This was about one year in O2 service. The valve designs are not significantly different but for scuba it definitely depends on the valve manufacturer. Talk about a twisty-turny just go to any weld shop! That's scary!

 

[Norwegian Cave Diver]

My understanding is air has 40 Ppm of hydrocarbons in it. Nitrox because if the filtering has 4 ppm of hydrocarbons. Nitrox and medical grade oxygen is much cleaner.
Anybody know if this is true??

 

[2airishuman]

My understanding is air has 40 Ppm of hydrocarbons in it. Nitrox because if the filtering has 4 ppm of hydrocarbons. Nitrox and medical grade oxygen is much cleaner.
Anybody know if this is true??

The Grade E standard requires a maximum of 25 ppm of gaseous hydrocarbons and 5 ppm of condensed hydrocarbons. Most compressor systems do much better than this.

Nitrox standards vary by agency as there is no government standard; some are no more strict than Grade E on hydrocarbons, others limit condensed hydrocarbons to 0.1 ppm.

Medical air (grade N) does not have to meet a hydrocarbon standard.

 

[michael-fisch]

Went digging around the Deco stop, didn't find the thread. Have a link?

The Deco Stop
From 03.06.2005

 

[nadwidny]

My understanding is air has 40 Ppm of hydrocarbons in it. Nitrox because if the filtering has 4 ppm of hydrocarbons. Nitrox and medical grade oxygen is much cleaner.
Anybody know if this is true??

This question about "hydrocarbons" always drives me nuts. I worked at a lab that did air and oxygen testing. When layman start talking about "hydrocarbons" it really doesn't mean anything. Methane is a hydrocarbon. It is present at around 2ppm in air. Always. You can't filter out methane. Medical grade oxygen always has a higher level of this "hydrocarbon". I've seen it anywhere from 5 to 50PPM in oxygen. All within the limits for medical grade O2, depending on which standard it was measured to. So the actual fact is that for "hydrocarbons" your air is most likely "cleaner" than O2. There are also limits for other "hydrocarbons" like ethane, etc but those rarely show up.

The term "hydrocarbons" needs to be purged from the diver lexicon and replaced with the terms that the standards actually call for.

So to sum up, whatever you heard is wrong. So very wrong.

 

[Diving Dubai]

What happened exactly? Valve turned too quickly, some malfunction with the first stage?

They never found out

According to the people on the boat it RB started to burn 2-3mins after tank was turned on, The first set of divers had just boarded to boat after their dive.

The replacement boat was named Burn