Exploding scuba tank kills one - Florida

[ktomlinson]

Okay, but you need to be aware that the aluminum tanks in this 1970 U.S. Navy report are not the same ones you think about today. These were a special tank made only for the U.S. Navy, with an old technology with a 3/4 inch opening at the top and a plug in the rounded bottom (look at the report and see). These are the tanks this report was talking about (aluminum):

These tanks are no longer in the inventory. They went out when US Divers Company came up with their newer aluminum tanks. I used them in the U.S. Naval School for Underwater Swimmers in 1967. They were in the inventory until probably the mid-1970s. They had a 15 year lifetime (as I recall), and could not be hydrostatically tested.

The steel tanks in this report were truly "low pressure" as they were the "steel 72" rated at 2250 psig (2475 psig at 10% overfill with the "+" sign, and at this pressure they were 71.2 cubic feet). This is what they looked like:

In short, you are comparing apples to oranges if you try to use this report to discuss today's steel and aluminum tanks.

Realize that during that time the U.S. Navy was involved in the Vietnam War, and they were doing all sorts of things to try to keep their SEAL teams going. Probably the same is true today. The probable purpose of this report was to see what would happen for SEALs and UDT who were in combat ops, and who's lives may have depended on that overfill. This is a long ways from cave diving for fun.

SeaRat

Thanks for pointing out that they changed, I did not notice that the aluminums were different than aluminums of today. I did think about the small number of steels in the study later after I posted, and dont think it is statistically relevant (n=3)...it sounded like they just had three steels laying around and decided to blow them up too. Cool pictures by the way.

 

[Brewone0to]

Oh, gosh! How could I forget those? Yes, well, if the tank's rated at 3300, why I'd be ok & not get nervous 'till at least 3600. But for regular old 80's with the 3000 psi working pressure, 3300's my "nervous number."

Rick

I don't fill AL tanks beyond DOT's wishes.
AL 80's to 3150-3200, and they end up @ 2950-3050.

People who do drastic overfills on AL tanks
are IMHO as instable as their fresh hot fills.

But LP steels are designed with proper fills in mind.
They even stamp your turn pressure
right on the shoulder of the tank.
Just in case you forget what it was.

 

[Rick Murchison]

...Does anyone remember reading about that terrible diving accident?
The one where the dive team didn't run out of gas
because they had plenty in reserves?...

Well, we may be reading about that terrible diving accident in this thread, eh?
Rick

 

[ktomlinson]

If it makes all those who don't believe that subtle overfills are safe.
If it is found to have been the absolute undeniable cause of this accident.
(the overfilling of an undamaged LP tank)

I vow to from this day forward to limit any slight overfills to a more reasonable
pressure than in the past. Therefore I will not fill my tanks over a maximum of say 4000psi.

Hopefully, knowing this will allow these people who don't believe that overfills are safe/sane
to sleep better at night, just knowing that my regs seats will never see 4400-4500psi should
make them happy that I will have swayed into their way of thinking
and started to drink their purple drink.

********************************************************************
My tanks flew through their last hydro test.
It is said that properly maintained 3AA steel tanks
will last in service for 40-50 years.

If I pump mine up a tad and they only last 10-15 years,
I feel that I will have gotten my money's worth from them.
At that point in my life I will likely change over
to RB to get the weight off my old back.

I believe that too much gas is always the correct amount.
Does anyone remember reading about that terrible diving accident?
The one where the dive team didn't run out of gas
because they had plenty in reserves?
Oops, I'm sorry,those divers lived and dove another day.

Donning Kevlar Suit.

RIP RV

You ever hear the one about the divers that made it back because they monitored their pressure, dove thirds or other appropriate plans? 4000psi may extend your dive, but it shouldn't make it any safer.

 

[Doc Harry]

...But hey, like I said, I really think that the talk of overfilling steel tanks is incredibly off topic...

Agreed. Let's get back on topic.
.
.
.
.

This is a very interesting accident.

In the past many of the explosions were caused by the 6351 alloy cracking.

Other than that, accidental scuba cylinder explosions are very rare and almost all non-6351 explosions occurred in cylinders that were not properly maintained (i.e., did not have a current hydro or VIP). Undetected corrosion was generally the culprit.

There was one cylinder explosion that occurred because of a manufacturing defect (slag was accidentally incorporated into the wall of the cylinder).

And, if I recall correctly, all of these accidental scuba cylinder explosions occurred during the filling process.

However, recently there was an O2 deco cylinder that exploded when the cylinder was accidentally knocked over. And I have some vague memories of a cylinder that exploded in the trunk of a car.

Can anyone else add something here, or correct me?

It will be interesting to see the details of this accident analysis. Does this accident fall into one of the above categories, or do we have a new and unique catastrophic failure here?

 

[Blue Sparkle]

I noticed that in a thread about this incident on another forum (Deco Stop) someone who sounded "in the know" said it was an AL40. Were 40's also made of the 6351 alloy? (I would presume so, but don't know.)

 

[DandyDon]

However, recently there was an O2 deco cylinder that exploded when the cylinder was accidentally knocked over. And I have some vague memories of a cylinder that exploded in the trunk of a car.

Those have both been covered in previous posts here.

Now, from Clues suggest pure oxygen may factor in fatal St. Petersburg scuba tank blast - St. Petersburg Times

ST. PETERSBURG — A witness getting his morning newspaper told police he saw a bright flash when a scuba tank exploded early Sunday morning.

The man holding the tank, avid diver Russell Vanhorn II, suffered what appeared to be burns in the blast that took his life and destroyed the condo he was standing in, according to St. Petersburg police.

As investigators continued their search Monday for answers in the puzzling blast, those potential clues suggest pure oxygen could have played a role in the explosion that killed the 23-year-old Iraq war veteran.

"That signifies to me that oxygen was involved and not just compressed air," said Doug Jackson, vice president of Bill Jackson's Shop For Adventure and a certified diving instructor and trainer. Jackson said pure oxygen increases the risk of fire and explosion.

Most recreational divers use compressed air — the same mix of 78 percent nitrogen and 21 percent oxygen we all breathe on land — in their pressurized cylinders. But pure oxygen is used for much more advanced and riskier diving, such as cave or deep diving.

Pure oxygen can be used for decompression, for example, to help divers purge themselves of nitrogen before surfacing from deep depths. That's to prevent decompression sickness: gas bubbles that can develop in the body and cause pain, paralysis and even death.

If pure oxygen was being used for a diving trip in the Tampa Bay area, Jackson said, that suggests Vanhorn may have planned to go cave diving.

Because of its explosion risk, pure oxygen should only be handled by skilled divers using special procedures and the utmost care, Jackson said.

Exploding scuba tanks are rare and devastating events. But in cases such as the 1981 blast that cost a Lakeland man his legs, the cause of the explosions appeared to be catastrophic failure of the pressurized metal tanks — not the gases inside the tanks.

Russell Vanhorn Sr. said his son enjoyed cave diving as well as other forms of diving in both Florida and his native Iowa. But his son was always careful.

"He enjoyed deep diving, he enjoyed open diving," said Vanhorn Sr., 55. "I know he did some cave diving, but he didn't do it on a regular basis.

"He would take pictures of underwater volcanoes down there. He said, 'Dad, I don't do it all the time. I do it with a bunch of guys and we're always safe.' "

The complicated nature of the investigation led St. Petersburg police to take over from the Fire Department.

Police spokesman Mike Puetz said investigators will track down the history of the exploded tank, determine who inspected and serviced it in the past, who recently filled it and with what kind of gases.

The tank was found split down the middle from top to bottom, lodged overhead in what was left of the kitchen ceiling. The blast shattered drywall and ceiling, collapsed walls, smashed furniture, blew out the doors and windows and damaged cars in the parking lot.

The Tampa Bay Regional Bomb Squad came in to inspect and empty the 11 other tanks found inside. Authorities did not say what was in the tanks.

Sara Swoch, 27, and Brent Stevens, 22, were inside the condo at 5865 37th Ave. N when the tank exploded at about 6:50 a.m., police said.

Swoch lives in the condo. She and Stevens were in different rooms when the tank blew up, police said, shielding them from serious injury.

Master scuba diver trainer Joyce Hannaseck of Narcosis Dive Shop in Tarpon Springs went diving with Russell Vanhorn II over the summer. She said the Tampa Bay diving community is anxious for answers.

"We're all just holding our breath to find out what caused this," she said.

 

[Blue Sparkle]

The latter article looks like the one from post #67 (it is sometimes hard to keep track though, isn't it?).

I'm curious about one thing: Is there any "tradition" of over-filling or changing burst discs on Aluminum tanks? I was under the impression that was more steel tanks, but it's a bit out of my league.

 

[Some X Dry]

If it makes all those who don't believe that subtle overfills are safe.
If it is found to have been the absolute undeniable cause of this accident.
(the overfilling of an undamaged LP tank)

I vow to from this day forward to limit any slight overfills to a more reasonable
pressure than in the past. Therefore I will not fill my tanks over a maximum of say 4000psi.

Hopefully, knowing this will allow these people who don't believe that overfills are safe/sane
to sleep better at night, just knowing that my regs seats will never see 4400-4500psi should
make them happy that I will have swayed into their way of thinking
and started to drink their purple drink.

********************************************************************
My tanks flew through their last hydro test.
It is said that properly maintained 3AA steel tanks
will last in service for 40-50 years.

If I pump mine up a tad and they only last 10-15 years,
I feel that I will have gotten my money's worth from them.
At that point in my life I will likely change over
to RB to get the weight off my old back.

I believe that too much gas is always the correct amount.
Does anyone remember reading about that terrible diving accident?
The one where the dive team didn't run out of gas
because they had plenty in reserves?
Oops, I'm sorry,those divers lived and dove another day.

Donning Kevlar Suit.

RIP RV

I believe the suit you should be donning is a NOMEX. Much more resistant to fire.

 

[DandyDon]

The latter article looks like the one from post #67 (it is sometimes hard to keep track though, isn't it?).

Yeah, I guess it is - sorry.