That must be really sad to feel such a way. Fortunately you have an IQ over 85 and a super powerful pocket computer to help you research, then you can make an informed decision for yourself. Hopefully that takes away some of your anxiety
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The Titan Submarine Imploded Due To Micro-Cracks In The Carbon Fiber Hull - Has A Carbon Fiber Bottle Broken/Exploded On Anyone?
- Thread starter SkeeterHawk
- Start date
That must be really sad to feel such a way. Fortunately you have an IQ over 85 and a super powerful pocket computer to help you research, then you can make an informed decision for yourself. Hopefully that takes away some of your anxiety
Boy that must make you feel good about yourself worrying and feeling sorry for me. I assure you it is only necessary for you not me……
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^^^^ This
The structure of the CF and resin will control the release of air in the event of a failure. And since these tanks we are use are so small (relatively), the pressure drops to a safe(r) level quite quickly. The energy source is incredibly limited in volume, comparatively. The potential for catastrophic/explosive failure is quite small. Think of it as more of a violent leak, and less of an explosion. Unless of course you're a youtuber who shoots a CF bottle with a handgun to show how "dangerous" they are. Really the only danger there was that guy's lack of common sense.
If a typical airgunner's CF tank/bottle does fail, the most likely injury would be to their hearing from the noise.
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Some fun math..
A 45min scuba tank is 6800 Cubic Centimeters in volume. At their fill pressure of 4,500 psi, air contains roughly 270 FPE per gram of air. The density at 4,500 psi is roughly .49 grams per cc, which means the weight of the air in this tank should come out to 3,332grams, or just shy of 8 lbs of air (7.35), or about 1lb shy of a gallon of water. One could check their tank weight empty, and then full and confirm, but this math is very close, although rounded and napkin'd slightly.
With 270 fpe per gram and 3,332 grams, that is 899,640 FPE that the tank is holding! Granted not all of that energy can be converted without loss, but in its compressed state, there inside your tank, contains nearly 1 million FPE. Reality is we're lucky to extract 15-25% of that, which is closer to 180,000 FPE, but that is if you took that tank down to 0 which you can't do in a pcp, so reality of that is as an air gunner you have 1/3-1/4 of that energy available to you, bringing it down to around 45,000-50,000 fpe. At 32 fills, shooting 1440 FPE per fill (60 fpe @ 24 shots), that comes out to...45,000 FPE, which is what I get out of my tank. My napkin math isn't far off there!
As the previous poster mentioned, you're more likely to damage your hearing than anything else in a tank failure event, although anything is possible, be safe!
-Matt
A 45min scuba tank is 6800 Cubic Centimeters in volume. At their fill pressure of 4,500 psi, air contains roughly 270 FPE per gram of air. The density at 4,500 psi is roughly .49 grams per cc, which means the weight of the air in this tank should come out to 3,332grams, or just shy of 8 lbs of air (7.35), or about 1lb shy of a gallon of water. One could check their tank weight empty, and then full and confirm, but this math is very close, although rounded and napkin'd slightly.
With 270 fpe per gram and 3,332 grams, that is 899,640 FPE that the tank is holding! Granted not all of that energy can be converted without loss, but in its compressed state, there inside your tank, contains nearly 1 million FPE. Reality is we're lucky to extract 15-25% of that, which is closer to 180,000 FPE, but that is if you took that tank down to 0 which you can't do in a pcp, so reality of that is as an air gunner you have 1/3-1/4 of that energy available to you, bringing it down to around 45,000-50,000 fpe. At 32 fills, shooting 1440 FPE per fill (60 fpe @ 24 shots), that comes out to...45,000 FPE, which is what I get out of my tank. My napkin math isn't far off there!
As the previous poster mentioned, you're more likely to damage your hearing than anything else in a tank failure event, although anything is possible, be safe!
-Matt
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our Carbon fiber Tanks can withstand the pressure inside because the pressure is pushing outward on the material..... carbon Fiber is designed to be strongest when it is being pulled or Tension, so it is strongest with an outward pushing pressure or tensile Strength, the mistake they made on the Sub is Carbon Fiber is Weak with an Inward pushing pressure, it crushes very easily, when I seen the video of the sub, I knew right away that they made a terrible mistake in design. that is why Carbon fiber tanks will work in the vacuum of space and not in the high pressures of the deep ocean,
please note the resin used is only a binding agent use to keep the fibers in place, it has very little strength value compared to the Carbon fiber itself,
a good analogy: take a Rope and pull on it, it is strong when being pulled and has good structural tension, now take the same rope and push on it, it becomes slack and has no structural tension... thus the rope only has Tensile strength.
please note the resin used is only a binding agent use to keep the fibers in place, it has very little strength value compared to the Carbon fiber itself,
a good analogy: take a Rope and pull on it, it is strong when being pulled and has good structural tension, now take the same rope and push on it, it becomes slack and has no structural tension... thus the rope only has Tensile strength.
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I had suspected that this would be the case.
I'm glad that in the example, that everyone was OK. I didn't think that the bottle would explode. You'd probably stand a better chance of that with an aluminum bottle since it doesn't have the CF wrap.
THIS is the fundamental question in my mind that started this thread. Our pressures are trying to get out, whereas the Titan had pressure trying to get in. This seemed counter-intuitive for what carbon fiber does, which is resist the tension of the pressure trying to get out. I have never seen the inside of the Titan, but they would have obviously have had to had a monstrous internal sub-frame to keep the pressure from crushing it, and then the CF was just a fancy "wrap" pushing on that sub-frame.
As @Hy-Score mentioned, this thread on the Titan tragedy (Sad as it is) is the basis for an interesting discussion on the properties of Carbon Fiber and when/where/how it should be exploited, not a discussion on gossip, as @steve-l suggested. I sincerely appreciate everyone's experience here as a lot of us have been using carbon fiber in different applications for years.
Great math, BTW, @Stubbers !
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Not sure about CF bottles failure rate but I am sure you would have to be about 50 shades of stupid to pay 1/4 mill to go that deep in that little thing to see a stupid ship. Darwinism at work folks….
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Yeah too rich for my budget.
And when I saw an interview with a submarine engineer who said there are 8-10 submarines doing the same tour but with subs that meet international standards I was amazed. Add to that the Titan concept was based on a philosophy of "innovation over safety".
Exploration and adventure is cool, I get it, but even Lewis and Clark had the best equipment available.
(And if I ever get to go to space or down to the sea in ships I’m damn sure not going with a budget friendly travel package.)
The dive operations were conducted in international waters for a reason, no regulations or oversight. Yeah thats a big red flag.
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People lost there lives in this exploration what the hell does this have to do with air guns… feel sorry for the people that lost family and give some respect. This should be locked out. Due to stupidity.
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This thread is not being disrespectful to the families of the people that lost their lives. It is simply looking for a lesson to be learned, that stems from a tragedy. You could say the same thing about the Holocaust, the shuttle explosion, the original sinking of the Titanic, the weekly slaughter in Chicago, etc. There are lessons to be learned in life regardless of the motivating factor. If anyone on here had been disrespectful to the families of those who perished, I would have chastised them myself.
So, back to the point. After this discussion, it is my belief that if you were to seal a CF bottle at sea level and you were to force it to go to 12,500 below the surface of the ocean, the lower pressure in the bottle coupled with the higher pressure of the water would certainly cause the CF bottle to implode as well since there would essentially be a vacuum inside it compared to the ton of pressure outside.
Now even more food for thought...
If you pressurized the bottle up to 280 bar and dropped it to the ocean, it is my belief that it wouldn't care the whole way down because the pressure inside the bottle would be consistently higher than that outside, until it got to the Titanic, at which point the pressure would be equalized. Does anyone disagree with this theory??
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I just thought of another one. Using the example above of filling the bottle to 280 bar and dropping it to 12,500 feet of depth. Once it gets there, what would happen if you opened it up with the nozzle facing downward? Would the tiny bit of air leak out or water leak in to equalize the tiny differential in pressure, but the air would just stay in there? Makes sense... 
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That concept is sometimes used on submersibles. At least on certain parts of them, mainly the bottles that house electronics. In some situations they also use oil filled bladders which compress relative to the depth and push oil inside the pressure vessels which effectively equalizes the pressure on the inside of the bottle to that of the outside. But the key is, whatever is inside the bottle needs to be able to withstand that pressure.
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took advantage of this pressure eq many years ago in a few subs.
The escape trunk was a small area that would be over pressurized just above the current depth pressure.
It allowed us to swim out of the submarine undetected and make our way to shore or nearby ship.
Always thought it was cool to do that, but hated and still do not like subs. Except at Subway.
Doc
The escape trunk was a small area that would be over pressurized just above the current depth pressure.
It allowed us to swim out of the submarine undetected and make our way to shore or nearby ship.
Always thought it was cool to do that, but hated and still do not like subs. Except at Subway.
Doc
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Interesting segment on CBS Sunday Morning. According to a retired sub captain interviewed the Titan was destined to fail. It was built with titanium, CF, and viewport of glass or plexiglass. 3 materials with different expansion contraction ratios. He summed it by saying subs only use one material for the hull for that reason. And finished by stating only a fool would have set foot in that submersible. The show had footage from a segment done about a year ago that showed the interior an build method. Also had the owner designer on..seem like someone that did things in unconventional ways..and bragged about it. He was the same guy that recently fired one of the project guys who raised safety concerns. Make one wonder
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I couldn't find a link to the video of the special that you watched, but I found the "meat and potatoes". Here is the text:
"McLaren theorizes that the Titan failed not because it was made of carbon fiber, but because it was made of three dissimilar materials: carbon fiber, titanium, and Plexiglas for the porthole. "When you have different materials, different molecular structure, they have different coefficients of expansion and compression. And then you make repeated cycles in depth? Of course you're gonna work that seal loose. And that's why submarines don't run around with any portholes at all, come to think of it. It's a weak point.""
Here is a link to the article I found.Since I originally posted this thread I have seen pictures of the interior of the Titan, and I must say that I am surprised that there aren't Titanium cross supports. Moving on.
This issue rings more true to me than the original theory about micro-cracks in the CF itself. My career is in analytical instrumentation, and a lot of these are running at over 1000C This causes big issues in thermal expansion coefficient of the different materials as the components heat up and cool down.
Again, this is a really interesting thread...based on the tragedy of a few explorers.
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Just a reminder for those that either do not know or forgot, CF tanks are actually aluminum and CF reinforced. Aluminum has poor fatigue resistance and the composite construction with CF prevents to a large degree the swelling and subsequent shrinkage related to charging and discharging related to use. The enemy of CF tanks is moisture. Prevent condensation and you will have very long tank life.
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I caution everyone to not jump to conclusions before we know the facts. That includes McLaren's wild ass conjecture. He does not know what actually failed or why either. In time, I sincerely hope we do find the cause and we will all benefit accordingly
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This link was posted here not too long ago. It's from Digital Wave, the original company authorized to do SCBA cylinder recertifications, and although not dated, it's likely about a decade old. It's 7 pages, but well worth reading, as it explains the history of the mythical 15-year life and general technology behind them. It is not an engineering paper - it's easy reading. A few key takeaways:
* The 15 year life for carbon fiber vessels is not
based on any experimental or historical data that
was performed using carbon fiber data.
* Three years of intensive studies requested by the
US Navy and DOT which followed ISO 11119-2
“at manufacture” testing procedures have
conclusively shown that the DOT-CFFC cylinders
can be safely used for at least 15 years beyond
their current lifetimes. (emphasis mine)
* The tests showed that the cylinders were still
meeting “at manufacture” design requirements,
even after 15 years of hard use (many of the
cylinders in the studies were from large
metropolitan fire departments and had seen
extensive use in the field). (emphasis mine)
* DOT-CFFC cylinders have been fatigued up to
24,000 cycles at developed pressure (5192 psi
for a cylinder with an operating pressure of 4500
psi), and did not have liner leaks. This number of
cycles, according to ISO 11119-2, results in an
infinite life cylinder. (emphasis mine)
My opinion is that even used fire department SCBAs are safe for our usage, for a long time to come. The paint ball cylinder mentioned in a post earlier in this thread that leaked was likely either significantly damaged (with the damage hidden by the wrap/bag it was in) or a poor grade, imported model.
https://docs.wixstatic.com/ugd/d00b78_72625b919876457fb9191418c1259c6b.pdf
* The 15 year life for carbon fiber vessels is not
based on any experimental or historical data that
was performed using carbon fiber data.
* Three years of intensive studies requested by the
US Navy and DOT which followed ISO 11119-2
“at manufacture” testing procedures have
conclusively shown that the DOT-CFFC cylinders
can be safely used for at least 15 years beyond
their current lifetimes. (emphasis mine)
* The tests showed that the cylinders were still
meeting “at manufacture” design requirements,
even after 15 years of hard use (many of the
cylinders in the studies were from large
metropolitan fire departments and had seen
extensive use in the field). (emphasis mine)
* DOT-CFFC cylinders have been fatigued up to
24,000 cycles at developed pressure (5192 psi
for a cylinder with an operating pressure of 4500
psi), and did not have liner leaks. This number of
cycles, according to ISO 11119-2, results in an
infinite life cylinder. (emphasis mine)
My opinion is that even used fire department SCBAs are safe for our usage, for a long time to come. The paint ball cylinder mentioned in a post earlier in this thread that leaked was likely either significantly damaged (with the damage hidden by the wrap/bag it was in) or a poor grade, imported model.
https://docs.wixstatic.com/ugd/d00b78_72625b919876457fb9191418c1259c6b.pdf
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