Posted: 11/29/2006 7:30:48 PM EDT
|
I was watching a show on the history channel and they were showing something about superconductors. A guy took something, cant remeber what it was, dipped it in liquid nitrogen with hid bare fingers took it out and then showed his example of the superconductor. Wouldnt that have froze his finger or something. I'm by no means a scientist but...... 
|
| The short answer is it would have frozen his fingers and most likely killed the flesh on his fingers from frost bite. It would fell like burning not cold. I know this from experience. There is a little trick you can do with liquid nitrogen; a drop on a flat surface of you skin will run off with out freezing your skin but if you dip you fingers in it or try to contain the liquid in your hand you will freeze the skin. Don't try though. |
I would have figured it would have frozen them "off" but... |
| I used to do temp testing with a nitrogen chamber 20 years ago.. We had more than a few "runaways" where the nitrogen valve froze open... first time it happened I shut the nitrogen off and opened the door.. there was a big landslide of frosty cold air that poured out of the chamber and the circuit boards we were testing shattered in a million pieces.. weird and dangerous stuff.. |
| Years ago, the Jet Propulsion Lab in La Canada, Calif(5 miles east of Los Angeles), let the public into their cryogenics lab, but due to safety restrictions because of the dangers of suffocating without notice from liquid nitrogen, the public has been since restricted. They demo'd quick a few tricks of super cold materials when subjected to liquid nitrogen. It was really impressive. Subsequent visits to the lab were not as intereting nor informative. |
youtube.com/watch?v=l8v_Ik0siQo 
|
|
what's happening is his hand isn't exposed long enough to actually contact the liquid nitrogen. When he dips his hand in, the nitrogen instantly converts to a gas forming a gas bubble around his hand, which protects him from the liquid. It's the same principle that makes the liquid nitrogen dance across a table. It's riding a bubble of gaseous nitrogen |
i saw a similar thing where some daredevil shit first wet his hand in water and then faster than shit dipped it in some hot liquid molten metal. The story was that the water evaporates and creates an instantaneous temporary barrier from the molten metal. fuck that shit. |
|
I got a chance to play with LN today, was pouring it on my hand. Due to the LN boiling upon nearing your hand it simply shoots off (similar effect to pouring it on the table, floor, papers, calculator, etc). If a LN bubble gets stuck on your hair follicles it will burn your skin through prolonged contact. Lesson learned today: LN is tons of fun! Creating a paper spoon out of a piece you tear out of a notebook is great for ladling small amounts. ETA: When I say play, I literally mean it, with a tank full of LN and time to kill, what does one expect to happen? |
+1 Notice how he warms his hand after each dip, and keeps it out longer and shakes it when it's been in too long? I've had 10 or so liters of that stuff spill over my leg and boot from the dewar fill station. No effect. It was partially gaseous by the time it hit. Now, the cryo tank tech told me of a guy at another site who was on the pad when tank ruptured. He tried to get up on the pipes or the fence, but it was too fast and too deep. Froze him up to the stomach. Game over. 
|
|
Working security for a defense contractor, we had several 2-story tall tanks of LN around the plant. Scary stuff! We had a runaway valve once: while the LN delivery truck was pumping, the filler safety valve stuck open, and the ENTIRE BUILDING got a full-pressure dose of LN! Only the people actually using it were affected though; but geez, the entire lab got dosed with it, and it ended up looking like a winter wonderland. I was sent down to take some pics (standard procedure for any lab accident), and then was told that the lab was a classified area; I had to surrender the camera for a day until the lab manager OKd the pics for release. ETA I had a friend who was a Marine in 'Nam; he said that the people servicing the F4 Phantoms used lots of LN. They had some fun stories involving LN and rodents... 
|
| We used Liquid Nitrogen to IQF seafood at a cannery I ran. As mentioned you can wet your hand and dip it quickly into the liquid without losing skin,fingers etc. We ran some fairly good sized exhaust fans as it reverts to gas on contact with air and displaces oxygen. We had a vessel overflow once and I got pretty light headed before I got the valve un-stuck. One of our underground lines developed a pin hole leak and and it took 6 months of thawing before we could dig down the 3 feet to repair it. It was great stuff if you had a bearing stuck on a shaft. Dip the end of the shaft in a can of LN and in a minute or so the bearing would fall right off. 321 degrees below zero IIRC. |