Exploding scuba tank kills one - Florida

[ktomlinson]

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0712815

Page 20 shows the rupture pressure of the three steel tanks that the Navy tested while testing their aluminum tanks. Two ruptured at 5300, one at 5400. That's too close to 4000 for me. Based on this document I would think it safer to pump a aluminum to 5000 than a steel to 4000. The pictures look like the tank ruptured instead of fragmenting.

 

[MarineResearch]

The fact that a government agency made a rule doesn't mean it's necessarily necessary.

The Legislature of the People's Republic of California might disagree with this statement. In fact, there is probably a law against this statement.

 

[ClayJar]

I do find it interesting that they didn't make different threads or disk sizes based on pressure to require the correct disk.

I have cylinders of several different service pressures that all use the same valves. They have different burst disks depending on the service pressure, but the valves themselves are identical. It does not surprise me that valve makers do not have completely separate lines for each potential service pressure.

(Of course, when it comes to burst disk assemblies, the right torque is important as well. If you just wrench it down with who knows how much "that should do 'er" torque, it doesn't surprise me to find burst disks failing well out of spec. I don't have the capability of experimentally analyzing torque vs. burst pressure, but if anyone does, it'd be informative. Of course, if you go by the "fix it when it fails" plan, eventually the burst disk is going to be corroded or otherwise weakened and fail below spec as well.)

 

[Splitlip]

Been lurking on this thread. Define "shorten its life" - if by that you mean catastrophic failure sooner rather than later, I think that's what we saw here. If you mean something else, I'd be interested in what that is. I am no diving expert, nor a cave diver, nor a metallurgical scientist. I happen to know one of each, but none have access to the tank in question.

PittCaleb

It would fail hydro, sooner than later.

 

[Larry C]

I didn't see anyone mention the air temperature at the time. If you fill the cylinder at the typical 70f rating and overfill it 25% for your cave fill, then the temp goes up to 95f, you now have almost a 40% overfill. If the burst discs are modified, you could easily blow the cylinder. A friend of mine left his doubles in the back of his pick-up truck in direct sunlight while he was working in a hot location. Both of his burst discs blew, and they were overpressure burst discs as well.
Usually, the person who is going to die from an overfill on a modified or unsafe cylinder is the poor guy who is filling it. Most of them won't touch an excessive overfill.

 

[Some X Dry]

Since the topic of overfill has been raised and may or may not be a factor in Russ's death, I would like to express my disgust at those divers that would condone and practice such reckless behavior as over filling tanks. As a new Cavern diver the issue of respect for safety in the Cave community was driven home many times during my training. Only took a post cert trip to the Caves to find out how much concern there was for my new teams safety as we arrived being the new kids at the Caves. How hypocritical you are to come and question my gear choices or my training in the name of my safety when you would consider it ok to overfill your tanks. Next time I am questioned about my gear and training I hope you will let me check your tanks pressure. I hear the crow here in FL tastes like ***t. If your going to talk the talk. Then walk the walk..

Perhaps this practice should die with Russ in his Honor. Whether relevant to his death or not. He was a Marine who served this country and died on 9/11 going to do what he loved best. Dive..

 

[Blue Sparkle]

Here is a new article: (They mention that it was an aluminum tank, although who knows how accurate that is at this point.)

Scuba tank explosion raises questions among divers | wtsp.com

Written by Eric Glasser
St. Petersburg, Florida -- The Tampa Bay scuba diving community is rasing questions about a scuba tank explosion Sunday that killed a local dive instructor.

23-year-old Russell Vanhorn died when the blast ripped through a condo on 37th Avenue North.

Detectives say they're looking at all possibilities, including whether Vanhorn's aluminum tank was faulty, or whether the Iraq war veteran used his knowledge as a dive instructor to alter his dive tank in some way.

Some who knew him describe Vanhorn as an avid cave diver. In order to maximize their "bottom time" or time spent underwater, it's not unheard of for some divers to over-fill their scuba tanks.

Dive shop workers say a membrane called a "burst disk" in the valve-stem is supposed to prevent such over-filling. But a skilled dive technician like Vanhorn, they say, would know how to add an extra burst disk -- or perhaps a stronger one -- in order to fill the tank beyond its normal specs.

"If that's tampered with, the safety is tampered with. And if the pressure gets too high, it's got nowhere to go but through the tank wall," said Bill Hardman, owner of Aquatic Obsessions Dive Shop in St. petersburg, "And that's a bomb."

Police do not suspect foul play. They are speaking with two other people who were inside the apartment when the tank exploded to see what they know about the tank, when it was last serviced, whether it was over-filled, and who last pressurized the cylinder.

"We have heard -- not necessarily from them -- but we have heard in the past, that tank modification is not unheard of in those individuals that like to cave dive," said Spokesman Mike Puetz. "So, again, that's just one aspect of this we're going to be looking at."

Witnesses say Vanhorn was carrying the tank to his car for a dive trip when the explosion occurred.

Please note that by pasting in the text of the article I am not trying to discourage people from clicking on the link and reading the article at its source. I always try to do that and I often find the comments there interesting. But, in future, an A & I thread's usefulness can be compromised if the article links are "dead" and their text is not available (I have read some past threads where this was a problem).

 

[JahJahwarrior]

Since the topic of overfill has been raised and may or may not be a factor in Russ's death, I would like to express my disgust at those divers that would condone and practice such reckless behavior as over filling tanks. As a new Cavern diver the issue of respect for safety in the Cave community was driven home many times during my training. Only took a post cert trip to the Caves to find out how much concern there was for my new teams safety as we arrived being the new kids at the Caves. How hypocritical you are to come and question my gear choices or my training in the name of my safety when you would consider it ok to overfill your tanks. Next time I am questioned about my gear and training I hope you will let me check your tanks pressure. I hear the crow here in FL tastes like ***t. If your going to talk the talk. Then walk the walk..

Perhaps this practice should die with Russ in his Honor. Whether relevant to his death or not. He was a Marine who served this country and died on 9/11 going to do what he loved best. Dive..

That defies the logic of accident analysis and Pareto analysis.

If we want to talk about what kills most cave divers then over filling tanks is way, way down a list that probably starts with driving cars.

I respect the dead but be logical about this. You do NOT know that overfilling was even at issue here, and if the tank was aluminum then even if it was overfilled you can cool your horses because the overfilling of aluminum cylinders is not condoned by any dive shop that I know of.


Regarding the presssure change I believe I accidentally called it absolute degrees, when it should be Kelvin. 70 f is 294 Kelvin, 95 f is 308 Kelvin. That should take a 3600 psi tank or 36% over fill to 3789 or 43% overfill. Can a genius please double check my math?

 

[Insta-Gator]

Well said. Hypocrisy has no place in diver safety.

Since the topic of overfill has been raised and may or may not be a factor in Russ's death, I would like to express my disgust at those divers that would condone and practice such reckless behavior as over filling tanks. As a new Cavern diver the issue of respect for safety in the Cave community was driven home many times during my training. Only took a post cert trip to the Caves to find out how much concern there was for my new teams safety as we arrived being the new kids at the Caves. How hypocritical you are to come and question my gear choices or my training in the name of my safety when you would consider it ok to overfill your tanks. Next time I am questioned about my gear and training I hope you will let me check your tanks pressure. I hear the crow here in FL tastes like ***t. If your going to talk the talk. Then walk the walk..

Perhaps this practice should die with Russ in his Honor. Whether relevant to his death or not. He was a Marine who served this country and died on 9/11 going to do what he loved best. Dive..

 

[DandyDon]

Although a tank can create a big explosion, it would be difficult to loft an adult through the air, and to create enough overpressure to blow out indows and doors....

Whatever exploded, it threw the diver thru the front door, threw the back door screen across the lot, broke the windows in the apartment, broke car windows in the lot, and more.

Not at all, if the tank was inside the apartment when it blew it could easily create that kind of damage and move someone. The explosion here in Fayetteville earlier this year did a lot more than shattering windows and it blew people across the room.

"The explosion here in Fayetteville"...?