Self promoting this video and sending it back into the queue for one more try; last queued Wednesday, May 27th, 2009 2:10pm PDT - promote requested by original submitter BreaksTheEarth.
something to do with rapid restructuring of the metals molecules as it cools... he pours it all slow, pours on rapidly cooling surface.. then it "jumps" ... reaction!
Judging by the sound and the spray, I'd say that the bottom of the container went from concave to convex almost instantly due to thermal expansion.
If you listen, the sound it makes is a metallic ping rather than a liquid pop, leading me to believe that the container "punched" the liquid into the air rather than some form of pressure forming within the liquid itself. If you look closely you can see that it completely clears one section of the container near the middle before it is refilled by the remaining liquid.
That's just my guess though. I don't see any evidence of a chemical reaction so all I can think of is the container changing shape very suddenly.
It looks to me like as he's filling it, the molten aluminum covers a pocket in the mold, creating an air bubble surrounded by the molten aluminum. The air bubble rapidly heats up and pops.
The metallic sound is harder to explain, but if any of the aluminum had solidified near the air bubble when it popped, that would make a metallic "ping."
Yeah, it's probably from pouring it into a cold mold. A similar thing happens if water comes in contact with molten aluminum - at a shop I used to work in a guy spat into a smelter full of molten aluminum and got sprayed in the face... wasn't very pleasant.
Judging by the sound and the spray, I'd say that the bottom of the container went from concave to convex almost instantly due to thermal expansion.
If you listen, the sound it makes is a metallic ping rather than a liquid pop, leading me to believe that the container "punched" the liquid into the air rather than some form of pressure forming within the liquid itself. If you look closely you can see that it completely clears one section of the container near the middle before it is refilled by the remaining liquid.
That's just my guess though. I don't see any evidence of a chemical reaction so all I can think of is the container changing shape very suddenly.
Betting you're right. I can't believe the moron was willing to put his face that close to blow it out after that happened. Shit, they are very lucky they didn't burn themselves.
Best Part is the Science Teacher/Lab Manager even says "You were wearing your full face shield?" and the guy totally lies "Oh yeah totally" He was just wearing GOGGLES!
If they are letting just anyone into labs can I get in there and play around too?!
Oh and I'm no science geek a but the container they were pouring it into caused the problem IMO.
If you look the receiving container has a piece of metal in the middle of it sticking up. That piece of metal (as the post above suggested) changed shape probably concave to convex or visa versa and POP the liquid goes flying out. If you watch the direction of the liquid several times over that is what happened IMO.
that's exactly what I was thinking hours ago. It seems like when Your welding and you hit an impurity and it splatters. Maybe there was a piece of shit or something or other in the receiver they where pouring into.
An air pocket appears to escape when molten metal reheats semi-molten metal, giving an escape route towards the center of the mold (spraying out the latest section of the pour). Maybe impurities on the surface, a bubble of air at the start, or even water from washing out the mold a short time ago could help explain.
Whatever the catalyst, expanding air flicks the hardening aluminum at the tongue in the center of the mold as it flies out, making the 'ping' sound.
Looks like a water droplet in the mold. They probably cleaned it very carefully before hand, but didn't heat it before pouring the aluminium in. Could be air expanding too, but water changes volume a hell of a lot more than air and would produce the reaction seen (I think water vapour is 1000 times greater in volume than liquid water). it's the violence of the expansion that causes the sound and the splattering metal.
I very much doubt the mold itself changed shape, it's a proper mold with think walls.
Does no-one else find it amazing that it takes them so long to figure out how to put the fire out?
Looking at the thickness of the mold, I doubt it was a shape change there. Rather, I'm leaning toward the suggestion that something vaporized. If you look closely, there's something in the angle where the bit of mold sticks up in the center, and that appears to be where the burst originates. That something is gone after the pop. (Either it's gone, or laminated with cooled aluminum.)
Oh, hey. Google. The first result for "molten aluminum explosions" details methods for preventing these types of reactions in industrial settings. Apparently, they call them aluminum-water steam explosions, and they occur as hypothesized:
As molten aluminum contacts the water, a steam film forms on the surface of the metal. The steam film can destabilize as the molten aluminum contacts other surfaces in the pit. When this occurs, the water spontaneously transforms from a liquid to steam leading to a high pressure steam explosion.
Yeah, I'm going with water bubble. Water is extremely energetic when it changes phase rapidly. Think the old "cup of water in a microwave" explosion or throwing water on to burning oil (eg. http://www.videosift.com/video/Kitchen-Oil-Fire-gone-terribly-wrong). Could be easily avoided by inserting the mold in to the furnace for about 10 seconds an end (if that is indeed the cause)
The cooling outer skin of the aluminium would have resisted the expansion of the steam which is why it took a second or so to pop after they had poured the bulk of the ingot, and why it caused such a big spray.
Both guys are, of course, extremely lucky.
As for putting it out, blowing on it??? Yeah, right. The moron trying to bat out a crucible that is up ended (hence there would be molten Al on the bench burning the bench top) and would be in excess of 660 deg cel, the melting point of Al, with a glove is just icing on the idiot cake at this point. /golfclap
I love how it takes them nearly a minute to think of the fire extinguisher. After the more intuitive approaches of blowing on the molten metal from 10 feet away then lightly slapping it with a glove.
Doesn't pure Aluminum react violently with air? I vaguely remember from highschool science my teacher say that Aluminum you find in common use is covered by an oxidized layer, but if you can ever get a fresh piece, thats been stored in a medium like oil or turps, as soon as you pull it out it will burst into flames. I think he may have even demonstrated. The way it's burning after the flare up kind of suggest that reaction might be going on.
Judging by the sound and the spray, I'd say that the bottom of the container went from concave to convex almost instantly due to thermal expansion.
Bravo for an interesting guess. But .... IMHO thats not what happened. There is not elastic force stored in a die cast iron receptical required to be released as a "pop"...and definatley not one that looks at LEAST 10 years old, and is probably way more, and has the same process done a few hundred times.
The expansive force on the concave surface would of slowly lost struct...ok fuck it.
Anyway I think there is a black residue from the last fuck nuts who where trying to make explosive substances for kicks. They never got around to cleaning it/they did not believe they had made anything of worth - and thats why you see some crud before in the corner, and not the instant after.
EDIT: And bravo for his mate for at least clearly instructing the dude to take of his glove.
>> ^Gabe_b: Doesn't pure Aluminum react violently with air? I vaguely remember from highschool science my teacher say that Aluminum you find in common use is covered by an oxidized layer, but if you can ever get a fresh piece, thats been stored in a medium like oil or turps, as soon as you pull it out it will burst into flames. I think he may have even demonstrated. The way it's burning after the flare up kind of suggest that reaction might be going on.
No, aluminium is a lot more stable than that. Other metals will react with air and moisture like potassium.
There's a very easy test of this. Get something aluminium and scratch the surface, revealing non-oxidised aluminium underneath. Watch for the flames...
I have actually had this happen to me except on a much larger scale. I used to melt scrap aluminum car parts in a large smelter. One morning I poured the ingot and it exploded in this fashion, hit the roof and rained molten metal down on me. Luckily, very luckily, I only got a couple of minor burns. Two things, the mold was cold and damp. Now I don't know which or both factors caused the reaction but I started preheating the molds with a torch and it never happened again.
>> ^savethecirclepit: I have actually had this happen to me except on a much larger scale. I used to melt scrap aluminum car parts in a large smelter. One morning I poured the ingot and it exploded in this fashion, hit the roof and rained molten metal down on me. Luckily, very luckily, I only got a couple of minor burns. Two things, the mold was cold and damp. Now I don't know which or both factors caused the reaction but I started preheating the molds with a torch and it never happened again.
They don't teach you that in ingot forming school?!
I like Asmo's suggestion that there was, for a brief moment, a cooled skin of aluminum over the water droplet, which allowed the steam pressure to build up. That might also explain the metallic "ping" when it pops.
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Judging by the sound and the spray, I'd say that the bottom of the container went from concave to convex almost instantly due to thermal expansion.
If you listen, the sound it makes is a metallic ping rather than a liquid pop, leading me to believe that the container "punched" the liquid into the air rather than some form of pressure forming within the liquid itself. If you look closely you can see that it completely clears one section of the container near the middle before it is refilled by the remaining liquid.
That's just my guess though. I don't see any evidence of a chemical reaction so all I can think of is the container changing shape very suddenly.
The metallic sound is harder to explain, but if any of the aluminum had solidified near the air bubble when it popped, that would make a metallic "ping."
That's my guess, anyway.
My Guess:
Judging by the sound and the spray, I'd say that the bottom of the container went from concave to convex almost instantly due to thermal expansion.
If you listen, the sound it makes is a metallic ping rather than a liquid pop, leading me to believe that the container "punched" the liquid into the air rather than some form of pressure forming within the liquid itself. If you look closely you can see that it completely clears one section of the container near the middle before it is refilled by the remaining liquid.
That's just my guess though. I don't see any evidence of a chemical reaction so all I can think of is the container changing shape very suddenly.
Betting you're right. I can't believe the moron was willing to put his face that close to blow it out after that happened. Shit, they are very lucky they didn't burn themselves.
If they are letting just anyone into labs can I get in there and play around too?!
Oh and I'm no science geek a but the container they were pouring it into caused the problem IMO.
If you look the receiving container has a piece of metal in the middle of it sticking up. That piece of metal (as the post above suggested) changed shape probably concave to convex or visa versa and POP the liquid goes flying out. If you watch the direction of the liquid several times over that is what happened IMO.
Whatever the catalyst, expanding air flicks the hardening aluminum at the tongue in the center of the mold as it flies out, making the 'ping' sound.
I very much doubt the mold itself changed shape, it's a proper mold with think walls.
Does no-one else find it amazing that it takes them so long to figure out how to put the fire out?
(Either it's gone, or laminated with cooled aluminum.)
Oh, hey. Google. The first result for "molten aluminum explosions" details methods for preventing these types of reactions in industrial settings. Apparently, they call them aluminum-water steam explosions, and they occur as hypothesized:
The cooling outer skin of the aluminium would have resisted the expansion of the steam which is why it took a second or so to pop after they had poured the bulk of the ingot, and why it caused such a big spray.
Both guys are, of course, extremely lucky.
As for putting it out, blowing on it??? Yeah, right. The moron trying to bat out a crucible that is up ended (hence there would be molten Al on the bench burning the bench top) and would be in excess of 660 deg cel, the melting point of Al, with a glove is just icing on the idiot cake at this point. /golfclap
That's right, nothing like extra oxygen to put out a small fire. Always works like a charm, that.
My Guess:
Judging by the sound and the spray, I'd say that the bottom of the container went from concave to convex almost instantly due to thermal expansion.
Bravo for an interesting guess. But .... IMHO thats not what happened. There is not elastic force stored in a die cast iron receptical required to be released as a "pop"...and definatley not one that looks at LEAST 10 years old, and is probably way more, and has the same process done a few hundred times.
The expansive force on the concave surface would of slowly lost struct...ok fuck it.
Anyway I think there is a black residue from the last fuck nuts who where trying to make explosive substances for kicks. They never got around to cleaning it/they did not believe they had made anything of worth - and thats why you see some crud before in the corner, and not the instant after.
EDIT: And bravo for his mate for at least clearly instructing the dude to take of his glove.
He lied to the teacher about having the face shield on.
Doesn't pure Aluminum react violently with air? I vaguely remember from highschool science my teacher say that Aluminum you find in common use is covered by an oxidized layer, but if you can ever get a fresh piece, thats been stored in a medium like oil or turps, as soon as you pull it out it will burst into flames. I think he may have even demonstrated. The way it's burning after the flare up kind of suggest that reaction might be going on.
No, aluminium is a lot more stable than that. Other metals will react with air and moisture like potassium.
There's a very easy test of this. Get something aluminium and scratch the surface, revealing non-oxidised aluminium underneath. Watch for the flames...
I have actually had this happen to me except on a much larger scale. I used to melt scrap aluminum car parts in a large smelter. One morning I poured the ingot and it exploded in this fashion, hit the roof and rained molten metal down on me. Luckily, very luckily, I only got a couple of minor burns. Two things, the mold was cold and damp. Now I don't know which or both factors caused the reaction but I started preheating the molds with a torch and it never happened again.
They don't teach you that in ingot forming school?!
i love the spanish at the beginning, then the total breaking character.
haha i'm the guy in the left for those 7 seconds of the video, the spanish was due to the video being a spanish project.