Acetylene explosion

[whateg0]

Just watched this news clip. Some burning debris from a nearby fire caught a truck on fire which had at least 1 acetylene bottle on it. The bottle exploded and injured several firefighters. Doesn't sound like the injuries were serious, but it does demonstrate how even when you think you took all the necessary precautions, stuff can still happen.

http://www.ksn.com/news/local/story/...je3ra4eBw.cspx

Dave

[brianko]

But please...when the s**t does hit the fan, DON'T DRIVE BY TO LOOK!

http://www.youtube.com/watch?v=RoatgaQrK28

(Watch carefully for the bottles that launch across the freeway. We heard this one happen from about 15 miles away.)

[Aerometalworker]

What I have never been able to figure out, is if its really the acetylene cylinder that goes up. They have plugs that melt out and vent the cylinder at 212F or if it goes overpressure. Our shop burned down many years ago, with 3 acetylene cylinders in it. All vented as they are designed and none "exploded". Now an oxygen or inert gas cylinder......

[whateg0]

Any kind of gas could potentially explode from sheer expansion of the gas as it heats up. I suppose that if a flame front hit the end opposite the safety plug the acetone could vaporize and expand faster than the plug could melt. I guess I don't want to try to test the theory in person, but it is interesting to consider. Maybe that could be a "Mythbusters" experiment! (I'd actually watch that one.)

Dave

[KPS]

Originally Posted by whateg0

Any kind of gas could potentially explode from sheer expansion of the gas as it heats up. I suppose that if a flame front hit the end opposite the safety plug the acetone could vaporize and expand faster than the plug could melt. I guess I don't want to try to test the theory in person, but it is interesting to consider. Maybe that could be a "Mythbusters" experiment! (I'd actually watch that one.)

Dave

closest I have been to an an acetylene explosion was many years ago, a guy I knew would put a small balloon inside another balloon, then inflate with accetylene, then place in a 55 gallon barrell then on top he would lay a stack of newspapers, & then ignite the top paper, in a min or two, KABOOM! shredded newspaper was 50 feet in the air.

I was alot younger, & dont know how much pressure he used to inflate, & wonder how much pressure was inside the balloon when 5+ stacks of heavy Sunday papers were placed on it to press it down. I think I saw him do that three times, but he did it a bunch to piss off his neighbors from what he said. he died a few years ago from accute alcohol injestion, so no way I could ask him.

Later,
Randy

[ptsideshow]

Originally Posted by Aerometalworker

What I have never been able to figure out, is if its really the acetylene cylinder that goes up. They have plugs that melt out and vent the cylinder at 212F or if it goes overpressure. Our shop burned down many years ago, with 3 acetylene cylinders in it. All vented as they are designed and none "exploded". Now an oxygen or inert gas cylinder......

I have to agree with, you on this one. Other than standing loose full cylinders, with out caps as at a fill plant falling over and the valve snapping off cause a chain reaction of other cylinders, falling over and snapping the valves off.

"from "Welding Essentials" book Acetylene cylinders contain one to four fusible safety plugs depending on their capacity. These fusible plugs, made of a special metal alloy, melt at 212'F(100'C). They also release the cylinder contents to atmosphere to prevent rupturing (and then exploding) when the cylinders is exposed to excessive temperatures, usually from a fire. Acetylene may have the plugs on the top, or top and bottom."

Full size lease cylinder


Other style acetylene cylinder, home owners size.

Bottom of a B cylinder with fusible plug, I will say that I have another B cylinder that has no fusible plug on it in either place.

"from "Welding Essentials" book Their purpose is to prevent the cylinder bursting from overpressure when it is heated. Oxygen cylinders have a small metal diaphragm in a section of the valve which burst.
Here is the High pressure valve, with the rupture disk the rupture disks (ruptures) above the cylinder test pressure 3360psi which is the cylinder test pressure. This valve came off an full size oxygen cylinder."

[ptsideshow]

Continuing along this thread, All high pressure cylinders whether inert or oxidizers have the same basic valve.

Here is my helium cylinder

Here is the 10³ft 75/25

Here is a 40³ft Argon

Here is a 125³ft75/25

So in theory and by design all cylinders have overpressure rupture relief devices built in.
With out the catastrophic release, of the contents caused by other things mostly the valves snapping off. No matter how fast the Temperature rises the fusible plugs will melt and start to releasing the gas inside the cylinder.

Now there can be certain conditions that do cause catastrophic releases.

I have seen a fusible plug develop a leak and then melt out when ta spark hit it. It did shoot a flame up and out quite the distance. I didn't get a good idea as to the length of it. But if somebody was near the cylinder they would have a good burn and had to change their shorts. As we were hot footing it out of the area. And looking back towards the cylinder. It was a 3/4's full cylinder, probably a 250³ft. It burned it self out as the fire chief was smart enough to know that if they put it out there would be free gas floating around.

[Roger]

This is from up close personal experience.
When cylinder valve's blow out disc blows it sounds like a gun shot followed by loud air flow.