Tank PSI - Over Filled, Drain or Dive?

[chrpai]

Just cause you never heard of it doesn't mean its not happened. Our parents never heard of a road bridge just failing, yet we've seen it how many times recently?

Dude, get real. There are around 6 million bridges in the US and there have been 111 collapses in 150 years. That works out to any one bridge collapsing in a given year at something like 1:4,400,000. I spend about 1% of my day driving over bridges. That means I have about a 1:440,000,000 million chance per year of being on a bridge when it collapses.

Not something work spending time worrying about... Nor do I worry about a scuba tank exploding while I'm diving.

 

[maniago]

Dude, get real. There are around 6 million bridges in the US and there have been 111 collapses in 150 years. That works out to any one bridge collapsing in a given year at something like 1:4,400,000. I spend about 1% of my day driving over bridges. That means I have about a 1:440,000,000 million chance per year of being on a bridge when it collapses.

Not something work spending time worrying about... Nor do I worry about a scuba tank exploding while I'm diving.

Dude, the only thing that is real is that tanks have a working pressure stated on them because of the safety designed into them. Its not just some number some tomdickorharry pulled out of his a.. Overpumping tanks is using then in a way that they are not designed for. Nothing more needs to be said.

 

[Dr. Lecter]

Its not just some number some tomdickorharry pulled out of his a...

Great, you'll have no problem telling us, then, how that precise number was selected and what the envelope above it is. Because otherwise, it's just a number someone put on there and said, 'Well, we think this is safe enough to put our asses on the line for it, but we also know Xpsi over won't hurt anything...but we won't tell you where X is because liability and safety and we know some of you dumbasses will overfill whatever number we tell you.' Which is another way of saying pulling a number out of his ass.

Your dogmatic concern with the stated working pressure is a joke in light of the simple fact that properly maintained tanks are just as safe at some unknown PSI over the number as they are at the number. As in, both pressures are within the stresses the tank is designed to handle without failing. The problem isn't the overfilling, it's the lack of knowledge as to where the real designed pressure limit is. But based on a ton of emperical evidence (see, e.g., decades of Florida fills), overfilling steel tanks by 500-1000psi isn't going outside that unknown limit.

 

[chrpai]

Nothing more needs to be said.

True, there is nothing more for you to say. You've got a lot more reading to do before. You might want to consider that Luxfer tanks are burst tested to 2.5x the service pressure. That's 7500 PSI. The DOT test pressure is 5000 PSI and they are cycle tested at service pressure 100,000 times.

Would I get in the habit of over filling an AL80 to 3800? No. Does it happen from time to time? Yes. It it a recipe for instant death? Typically not. Will it shorten the life of the tank? Some. Hydro every 5, inspection annually is enough to make the odds really really good that you'll be fine.

 

[RJP]

Steel tank? 4,000psi? Dive it. Though I'd be more comfortable with a DIN reg, due to the possibility of extruding an o-ring with a yoke.

 

[ianr33]

My understanding is that tanks typically fail during the fill cycle. Can anyone give me an example when a tank ruptured "while a diver was wearing it"?

Not the tank,and not wearing it at the time, but.........standard burst discs,cave fills and Texas sun can be a bad combination!

 

[soonerwink]

They had just filled it.

It was probably still hot, so pressure would come down a couple of hundred pounds.

 

[chrpai]

Not the tank,and not wearing it at the time, but.........standard burst discs,cave fills and Texas sun can be a bad combination!

While a burst disc is an exciting event, it's not a tank failure.

 

[macado]

Why is this even a question? In layman's terms...steel tank, go diving and enjoy a little gas! Aluminum, bleed that sucker down a little bit..

Not getting into too deep into the technicalities but the test/hydro pressure on that tank is 5250psi. You're not even close to test pressure use for hydro or close going beyond the elastic expansion of the steel tank. At that point you would have to worry about burst discs too.

 

[spectrum]

Why is this even a question? In layman's terms...steel tank, go diving and enjoy a little gas! Aluminum, bleed that sucker down a little bit..

Not getting into too deep into the technicalities but the test/hydro pressure on that tank is 5250psi. You're not even close to test pressure use for hydro or close going beyond the elastic expansion of the steel tank. At that point you would have to worry about burst discs too.

Because the OP tried that, had an O-ring failure and is having second thoughts. A steel tank does not a diver make.

Pete