cylinder valve shears off, tank travels 1/4 mile

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abnfrog

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I remember reading in Skin Diver mag years ago about a 72 full, 2250 PSI, that fell valve 1st from a vise. It fell about 3 feet and broke the valve. This happened in the basement of a 3 floor tenement building plus attic. The tank went out the roof and came down from ?? high went thru the roof and floor of a parked car and buried 1/3 of itself in the street. Nobody was hurt not even the "repairman".

I've never forgotten the story it installed a lifetime healthy respect for high pressure gas.
 
I remember seeing where an old 72 went through the meal trashcan full of water and then the cinder block wall at a dive shop in Atlanta back in the 70's. I don't believe they ever found the tank after it left the filling room as it went into the woods across the street.........
 
One of the Facts to Consider is that the report is with regard to a cylinder of Halon. Halon is stored as a pressurized liquid, not a gas. The ejection of the liquid produces more propulsion than would the ejection of a comparable volume of air (because of the significantly higher mass), and once most of the liquid is ejected the remaining liquid will boil produce a large volume of gas, much larger than the volume of gas in a scuba cylinder filled to 600 PSI.

While scuba cylinders do pose significant risks from a sheared valve, I do not believe that it would be possible to get a scuba cylinder filled to 600 PSI to travel 1/4 mile horizontally due to a sheared valve, even under ideal conditions.
 
you may be right
 
The thread name is misleading, the cylinder travelled 1/4 mile, not the valve which it sort of implies. This is consistent with the Mythbuster's test back in about 2007 or 2008. The one there went through a Bessa block (cinder) wall and smashed another one before stopping. Not sure of the pressure in that tank.

See the video .
 
The thread name is misleading, the cylinder travelled 1/4 mile, not the valve which it sort of implies. This is consistent with the Mythbuster's test back in about 2007 or 2008. The one there went through a Bessa block (cinder) wall and smashed another one before stopping. Not sure of the pressure in that tank.

See the video .
There are a few details that need to be considered. For one, older tanks with older valves that have larger orifices are more dangerous because force in this situation is basically PSI times cross sectional area. Because of this, a valve who's threads fail would give the largest cross sectional area possible & the most pronounces effect.

Another detail to consider is the space that the tank has for acceleration before it hits the wall. Longer acceleration =
more speed = more impulse energy.

The tank looked like a 244 cf industrial tank. Off the top of my head, I think that they are rated for a little over 2kpsi, but it's been a while since I worked with them.
 
hers another incident , whats different was it had only 600 psi in it , ..... Cylinder Training Services. 600 PSI Cylinder Travels 1/4 mile
Basic Newtonian mechanics tells us that S=ViT+1/2ATT. On the way down, acceleration is 32 feet/second squared. On the way up, F=MA gives us our acceleration. As pressure decreases, the force decreases, & so does the weight of the cylinder. This creates a fairly sticky calculus equation that I don't want to get into, so I'll just use some approximations. Lets say that the opening in the end of the cylinder is 2 square inches (which would be on the large side). 600psi x 2 sq in =1200 pounds of thrust. The cylinder was said to be around 200 pounds. 1200=200 x A Therefore, A = 6 on the way up. If we estimate that it takes 10 seconds to empty the tank (a long time for a 2" opening) and estimate that average force over 10 seconds is half of max because force decreases as gas escapes then A = 3 & T =10. Since initial velocity is zero, S=Vi T + 1/2 ATT becomes S = 1/2 ATT S = 3 x10 x 10 /2 = 150 feet traveled during acceleration. If we assume that it went up at 45 degrees (which gives the longest total travel distance) then the vertical distance is 150 x sine 45 or about 106 feet high while covering 106 feet of distance (forgetting that air has some resistance due to viscosity). At this point, we must also consider that the velocity is 30ft/sec at a 45 degree angle, and the upward component of that would be 30 sign 45 or about 21. With acceleration due to gravity at 32, rise time would continue for another 2/3 of a second, giving us another 21 feet of distance for a total of 171' so far. Using the same formulas, we calculate the fall time as roughly 170 = 1/2 x 32 x TT or TT = 19.6 so T = about 3,25 more seconds at 30 ft/sec, that only adds about another 100' for a total of like 270 feet horizontal travel or about a football field (American football), not 1/4 mile.

Those calcs were off the top of my head. It's late. I'm tired. I had some estimations in there to keep it simple. I neglected a few influences for simplicity (mostly on the side of the cylinder going further). Maybe I made a mistake or two, but from those quick numbers, I find it hard to believe that 600psi would push that cylinder that far unless Haylon has some gigantic expansion rate that would keep the pressure going for much more than 10 seconds. Then again, I don't know jack about Haylon, so maybe that's that case.

Anybody care to correct my mistakes?
 

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