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publius
2013-Aug-29, 04:07 AM
I just had a little superheated water incident. It's one of those things that reminds you how dangerous little things can be. I had some hamburger meat patties in the frying pan that I cooked for supper and got hungry again just now and decided to heat it up. Waited a few minutes with the eye on med low, then went to check. I had lifted the lid off a few inches with one hand and was picking the pan up with the other, when "Pooft!" and then splatter all over me and everything else.

What had happened was there was some water in there with grease floating on top. That water underneath got superheated somehow, and when I disturbed it, she vaporized spectacularly. Luckily for me, the flying grease wasn't too hot somehow. It was warm, but not scalding hot. It may have been a hot spot on the pan, actually that managed to superheat a spot of water. There wasn't enough water in there to cover the bottom of the pan, just little spots.

At any rate, that was quite a little "incident" in the kitchen.

*** ETA: I searched around on this, and apparently oil on top of water, or heating any such type of non-mixing "mixture" where the liquid with the lowest boiling point is the on the bottom below something less dense with a higher boiling point, is begging for something like this to happen. I saw reference to mishaps of this nature in various industrial processes -- keeping it stirred is necessary. And the oil on top also hinders evaporation, allowing the water trapped underneath to heat that much faster.

novaderrik
2013-Aug-29, 10:39 AM
so were the burgers worth it?

Hornblower
2013-Aug-29, 01:43 PM
What happened was that the overlying grease put a small amount of pressure on the water and raised its boiling point, allowing it to remain liquid at a temperature above 100C. When the containment failed the water was free to flash into steam and splatter the grease all over the place.

The same thing can happen on a larger and more violent scale if a pressurized boiler ruptures. A particularly gruesome example occasionally happened with steam railroad locomotives. If the water level in the boiler got too low the top of the firebox would overheat, and the next time the water touched that surface it would rupture, and the result would be a violent blast of many tons of a mixture of steam and boiling water into the cab. It usually was sudden death for the engineer and the fireman, and it could hurl what was left of the boiler high into the air.

BioSci
2013-Aug-29, 04:12 PM
*** ETA: I searched around on this, and apparently oil on top of water, or heating any such type of non-mixing "mixture" where the liquid with the lowest boiling point is the on the bottom below something less dense with a higher boiling point, is begging for something like this to happen. I saw reference to mishaps of this nature in various industrial processes -- keeping it stirred is necessary. And the oil on top also hinders evaporation, allowing the water trapped underneath to heat that much faster.

Or.. in my experience, significant water vapor collects on the lid (large droplets), then if the pan juices have mostly evaporated, the pan temperature can raise significantly above boiling. Upon tilting the lid, the accumulated water drops and is flash boiled by the hot pan spewing steam and hot oil...

Ouch!

Kaptain K
2013-Aug-29, 06:24 PM
I was involved in an incident (colateral damage) with superheated sulfuric acid! A co-worker was heating a flask of acid that erupted just as I happenen by:rolleyes:. I spent five minutes over the eye wash, but was otherwise unhurt, although it totally destroyed a one of fifty tee shirt I had gotten as a crew member at a rock-concert.

Nick Theodorakis
2013-Aug-29, 07:32 PM
Wow! You got lucky it wasn't worse, considering that the acid must have eaten all the way through the protective lab coat you must have been wearing, right? ;-)

Nick

JohnD
2013-Aug-29, 08:57 PM
In contrast, a super-cooled water incident (rather less dangerous)

Helping at an outdoor event, our medical team had a tent and a fridge, that we kept bottles of water in.
It was for cases of dehydration and/or heat stroke that we anticipated (Yeagh, and for us!)
The weather was so hot that someone turned the thermostat right down, I mean to minus 11.
I took out a bottle and cracked the screw cap.
There was an odd noise, a sort of soft crackle, and the bottle of water froze in my hands. What had been clear liquid a moment ago was now solid ice, clouded with tiny bubbles of air!

I couldn't reproduce it with other bottles, most of which had frozen already. This must have been a very pure sample with a very clean bottle, and the sudden movement of the cap, or perhaps the release of small particles as it was moved on the seal, initiated the freeze. You could see a column in the ice bubbles where it had spread down from the cap.

JOhn

publius
2013-Aug-30, 04:52 AM
Or.. in my experience, significant water vapor collects on the lid (large droplets), then if the pan juices have mostly evaporated, the pan temperature can raise significantly above boiling. Upon tilting the lid, the accumulated water drops and is flash boiled by the hot pan spewing steam and hot oil...

Ouch!

Yes. My trouble is usually water droplets falling off into hot oil/grease and spitting like crazy, making annoying spatter all over the stove. I got to where I like to put wine on beef (hamburger, steaks, etc) and even pork chops. I tasted someone's who did that, liked it, and have been doing ever since. Pouring the wine on top would usually result in the spitting, so I learned to take it off heat, let it cool for a few moments, then pour the wine and put it back on. :)

publius
2013-Aug-30, 04:53 AM
In contrast, a super-cooled water incident (rather less dangerous)



I've always wanted to see a flash freeze like that, but never have.

Trebuchet
2013-Aug-30, 03:15 PM
I've always wanted to see a flash freeze like that, but never have.

I've seen it happen with cans of soda. Also with beer poured from a bottle into a glass from the freezer. Kind of spoils the beer.

Fazor
2013-Aug-30, 08:49 PM
I've seen it happen with cans of soda. Also with beer poured from a bottle into a glass from the freezer. Kind of spoils the beer.

Yeah; it's relatively easy to do with beer. We had frozen mugs and some beers that were in bottles out in a garage in the middle of winter. The beer was cold, but not enough to freeze. But the second it hit the frozen mug (and I assume the carbonation lowering the density of the liquid has something to do with it) it froze. Beer slushies for all! (They're gross. Don't do it unless you want a science experiment.)

grapes
2013-Aug-30, 11:48 PM
A friend was making bullets, heating lead on our kitchen stove. He had "washed out" an ingot mold and when he poured the lead into it, his face was spewed with small hot iron pellets. It looked like instant acne. Every last drop had missed his unprotected eyes. He never did anything without goggles after that.

PetersCreek
2013-Aug-31, 12:48 AM
A friend was making bullets, heating lead on our kitchen stove. He had "washed out" an ingot mold and when he poured the lead into it, his face was spewed with small hot iron pellets. It looked like instant acne. Every last drop had missed his unprotected eyes. He never did anything without goggles after that.

As a reloader, I have to say YIKES...and that I hope y'all have exceptional ventilation. I don't cast bullets these days but if I did, it would be outdoors or in the garage with the door open and a strong fan running.

publius
2013-Aug-31, 06:06 AM
What doesn't kill you teaches you not to do it again. Wasn't there some finding or something along these lines in evolutionary psychology or whatever discipline it was, where "street smarts" or similiar wasn't so much what you knew to do, but what you knew *not to do*? Those that do deadly acts gets killed, and we learn not to do such deadly things and not so much learn to do things positively that help survival.

I can tell you some stunts I did with fire and flying projectiles. What burned in my head to use safety googles (actually I prefer a full face shield now) was an exploding ball bearing. It was stuck on a shaft (as they are all wont to do) and I was beating it with a hammer and punch trying to move it. Well, the races are made out of glass hard steel alloy and a chunk shattered and sent a piece flying right by my head making a dent in whatever was behind me. I realized had that thing been just an inch to the side, I would've likely been ol' One-Eye.

And then with my welding and torch adventures, I've pulled some doozies. Back in the '90s, my father and I were doing making some bodies for a flat bed truck. My father hit the idea of half-in-half. Half thick sheet metal on the bottom and half plywood, which was nice. The half metal was good for things like gravel, where a full load wasn't that piled high anyway. Anyway, I was squated down running some long beads, and I thrown on old denim shirt for protection, but hadn't tucked the tails in. I was going along and smelled something, then she blazed up all around me. I had set my own shirt on fire. I got it off without damage, but that scared the daylights out of me.

Then one time I was going at something with my big side grinder, making a shower of sparks that was long and wide. Providence made me noticed that a 5 -gallon bucket, with an open top was right in that spark shower path. I hadn't hit it yet, but I wouldn't have shortly if I'd kept moving. There was about 2" of gasoline in that bucket, which I'd been using to clean something earlier and had forgotten about. That shook me up pretty good, and after that, I always check for anything like that before making sparks.

DonM435
2013-Aug-31, 01:31 PM
Wow! You got lucky it wasn't worse, considering that the acid must have eaten all the way through the protective lab coat you must have been wearing, right? ;-)

Nick

Once in chem lab, I messed up while pouring a solution into a burette, and got one arm soaked in dilute sulphuric acid or some such. No harm done, I just wiped it off and went on.

The next time I took my lab coat off the hanger, the entire sleeve crumbled into little shreds and patches.

The shirt I'd been wearing underneath it, however, was fine, didn't even lose any color. The lab coat must have had some extremely soluble material in its cloth.

JohnD
2013-Aug-31, 09:48 PM
On eye protection. D'ye know how the top of a cold chisel, or a bolster, gets that motheaten look, where it gets hit with the hammer?
That bulge of steel is under enormous accumulated stress. Eventually, a piece breaks off, and as it does so, it's moving as fast as a bullet.
If you, or the workmate on the other side of the room is looking in the wrong direction, that steel fragment will go right into your eye.

Always grind the rim off, plus a bit extra to make shallow cone, to relieve the stress and leave no pieces ready to come off.
John

publius
2013-Sep-01, 03:12 AM
Sulphuric acid will do a number on a clothes. In the guise of battery acid, I don't know how many shirts I've ruined. Anytime I handle a battery, such as changing one out, the shirt I'm wearing will have holes develop after the next wash. :) The shirt I'm wearing now will probably develop just because I'm thinking about messing with a battery. Denim, as on blue jeans, seems to fare a little better. It will get a white spot which will last a while, but will eventually turn into a hole.