Tank hit by propeller explosion

[mth1993]

Thank you for posting the article from st pete. I remembered the story and was searching for it but could not find it.

 

[bamafan]

The tank in st pete was filled with oxygen and wasn't even oxygen cleaned. Yeah it definitely exploded but this was an oxygen explosion.

 

[Griffo]

Definition of Explosion - a violent expansion in which energy is transmitted outward as a shock wave.

I'd say a 3000# tank opened up would produce a violent expansion, and I would not want to be in the way. I was always trained, even before SCUBA, that a HP tank should be respected, not only for it's contents, but for the damage the HP itself can produced when loosed. I cringe, and look for cover, the way some divers handle their tanks.



Bob
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This space for rent.

The pressures we play with can certainly be dangerous. This accident always has me standing back from tanks as they are being filled

Dangers associated with mismatching portable (scuba) cylinders and valve fittings - Workplace Health and Safety Queensland

 

[Mustard Dave]

This fella was saved by his 'oxygen tank' when it was hit by a propeller:

Saved by his oxygen tank: Father-of-two tells how he cheated death in horrific diving accident | Mail Online

 

[Diver0001]

I saw an industrial cylinder explode, with a little help from a very small shape charge. I believe there was enough force at 2000 PSI to sink a small boat. I doubt a fiberglass boat would survive an exploding Scuba tank that was near full. The point is you would probably hear of boat and passenger damage if an explosion occurred.

I can see it happening with a stainless steel high speed prop versus an Aluminum Scuba bottle. The failure caused by a rifle shot would be much different than a prop. OK, who is going to send this one to Myth Busters?

If the tank was under water, which I assume it would have to be if it was opened up by a propeller, then the water would absorb most if not all of the force. If I'm not mistaken hydrostatic tests are done with the tanks submerged for this reason.

In an accident like that one I wouldn't suspect the air escaping from the tank would be the thing that would kill the diver. Once the tank is open then the diver has no air and if they're also injured, disoriented, in panic or unconscious because of the collision then I would suspect drowning as opposed to being blown to smithereens.

R..

 

[Storker]

Mythbusters couldn't even get a propane tank full of propane to explode by shooting it.

No wonder. Over here, if the fire brigade has a situation involving gas tanks - usually propane or acetylene - in a fire, one of their options is to call in a shooter who can puncture the tank(s) from a safe distance before the increased pressure makes the tank(s) rupture violently. It's happened more than once.

For obvious reasons, the shooters prefer FMJ rounds... :cool2:

 

[Bob DBF]

If the tank was under water, which I assume it would have to be if it was opened up by a propeller, then the water would absorb most if not all of the force. If I'm not mistaken hydrostatic tests are done with the tanks submerged for this reason.
R..

In a hydrostatic test the tank is filled with water to pressurize the tank, since water is non-compressible, if the vessel should rupture it takes little release to bring the pressure to ambient making the event much safer. It is submerged in an enclosed pressure vessel completely filled with water to measure the expansion and contraction of the tank under pressure using a water column from that pressure vessel.

Hope that makes sense.


Bob
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Always use the right tool for the job. A hammer is the right tool for any job. Anything can be used as a hammer.

 

[Diver0001]

Thanks Bob. I stand corrected.

R..

 

[Akimbo]

If the tank was under water, which I assume it would have to be if it was opened up by a propeller, then the water would absorb most if not all of the force...

Not quite. We were taught how to use shallow water to direct explosive forces up, which is exactly the situation on a small boat propeller. The force of an explosion starts out omnidirectional as it seeks equilibrium with the pressure around it. The water to the sides and below is non-compressible and very difficult to displace due to the weight and bottom. A few feet of water is much easier to displace, thus focusing the explosive energy up.

This property is the basis of most modern torpedoes. They don’t try to hit the side of the ship anymore. They are designed to explode under the ship and the gas bubble breaks it’s back. Think of suspending a ship at a point fore and aft with nothing in the middle to support it. It looks like the upward force of the water is the killer, but the giant gas bubble amidships is the coup de gras.

To expand on Bob’s hydro explanation: It is exceptionally rare that a cylinder being hydro tested fails by splitting open. They fail because they expanded beyond acceptable limits.

 

[luscioman]

Here is the mythbusters video

MythBusters - Jaws Special - YouTube