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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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Tanker accident
I just heard on New Hampshire Public Radio that Rt 89 was closed down because a
tanker filled with liquid nitrogen had gone off the road. The road was closed because of the danger of explosion! Sigh..... Earle Rich Mont Vernon, NH |
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ERich10983 wrote:
I just heard on New Hampshire Public Radio that Rt 89 was closed down because a tanker filled with liquid nitrogen had gone off the road. The road was closed because of the danger of explosion! Sigh..... Actually quite real. Nitrogen supercools tarmac. Oxygen condenses on tarmac, soaks in. Tarmac goes boom as it warms up, or a fly lands on it. |
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Well... My understanding is that liquid nitrogen is not shipped under
(much)pressure. It is just shipped in a insulated container and is constantly boiling off. I suppose if the tank's intergrity wasn't compromised but the vent got damaged or plugged the whole thing could go bang. Just a guess. -Kris ERich10983 wrote: I just heard on New Hampshire Public Radio that Rt 89 was closed down because a tanker filled with liquid nitrogen had gone off the road. The road was closed because of the danger of explosion! Sigh..... Earle Rich Mont Vernon, NH |
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Actually quite real. Nitrogen supercools tarmac. Oxygen condenses on tarmac, soaks in. Tarmac goes boom as it warms up, or a fly lands on it. Interesting, although I don't recall any warnings about this in all my years of working with cryogenics, though. LN2 isn't all that much colder than the condensation temperature of oxygen (-270 F) but if the tarmac got to full LN2 temp (-320 F) it could work. Certainly LN2 doesn't cause oxygen to condense appreciably in typical lab conditions. Now, chilling from liquid hydrogen definitely does it. On un-insulated flex lines, the LH2 (at -420 F) would condense oxygen and nitrogen directly out of the air, and it would actually 'rain' in the vicinity of the LH2 lines. The LN2 tended to gas off fairly quickly, leaving it LOX enriched. If the droplets of liquid air hit grease, you got little *poofs* as they ignited. Note, temperatures are from memory, I don't have a chart handy. DT |
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Correction, oygen condenses at -297 F, not -270 F, so the LN2 is only about 20
degrees colder. I think it would take unusual circumstances to condense oxygen on an LN2 cooled road, since it frosts over with ice so quickly. DT |
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DT wrote:
Actually quite real. Nitrogen supercools tarmac. Oxygen condenses on tarmac, soaks in. Tarmac goes boom as it warms up, or a fly lands on it. Interesting, although I don't recall any warnings about this in all my years of working with cryogenics, though. LN2 isn't all that much colder than the condensation temperature of oxygen (-270 F) but if the tarmac got to full LN2 temp (-320 F) it could work. Certainly LN2 doesn't cause oxygen to condense appreciably in typical lab conditions. But you've not got whole tanker-loads of LN2. I'm not saying it's certain to happen, just that there may be a risk. |
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On Wed, 17 Dec 2003 15:23:03 -0500, Tom Quackenbush
wrote: I just heard on New Hampshire Public Radio that Rt 89 was closed down because a tanker filled with liquid nitrogen had gone off the road. The road was closed because of the danger of explosion! Sigh..... I'm not qualified to comment on the explosion danger (although I found Ian's response interesting), but I'm wondering if you know whereabouts on I89 the accident occurred? I don't want to be anywhere near a large discharge of LN2. Never mind the explosion hazard, what do you plan on breathing? Remember the climax of the movie Terminator 2? After that tanker burst, a nitrogen atmosphere may not have bothered Arnie, but what was everybody else using for a source of oxygen? ## Your CA governor can beat my premier-- and I wish he would! |
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In article , Ian Stirling says...
But you've not got whole tanker-loads of LN2. I'm not saying it's certain to happen, just that there may be a risk. I don't think this is a real-world risk. You may possibly be thinking of liquid *air* where there is already a considerable amount of oxygen present. The nitrogen will indeed distill off and leave behind a considerably enriched mix, and this could in principle light off. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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Well you could always get nitrogen nacosis. Just like you get that
high from going down to deep when scuba diving. It comes from being saturated with nitrogen. I had it a couple of times, and it was pretty neat at the time. It all dissapated just about imediately when you got up to a certain depth, but it would creap up on you without your knowing it very easy. I made some deep dives with experienced divers that were accustomed to it, and knew what they were doing, so I felt at the time I was in good hands. Now I tend to think otherwise as it was really a foolish thing on my part. Things you do when your young and survive! Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
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Roy wrote:
Well you could always get nitrogen nacosis. Not at 1 atmosphere. Rick |
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Hitch wrote: (ERich10983) wrote in : I just heard on New Hampshire Public Radio that Rt 89 was closed down because a tanker filled with liquid nitrogen had gone off the road. The road was closed because of the danger of explosion! Sigh..... Earle Rich Mont Vernon, NH Maybe they're afraid the venting system was damaged and the tank might explode as the nitrogen warms up? Either that, or the laws of physics are a little different in New Hampshire and elemental nitrogen is explosive? You can't expect the vent system to work right if the tank is on its side. When the regulator gets frozen, it could freeze open or closed. I'm sure such a huge dewar has to have several safety releases, but the activation of the safety release could still be quite messy. While the release of tons of liquid Nitrogen onto a road would not technically be an explosion, it could still release a HUGE amount of gas pretty suddenly. I sure wouldn't want to be anywhere near it if the tank cracked or if a safety relief valve that happend to be under the liquid level was forced to open. Still, not quite as exciting as a gasoline tanker blowing up. I had the occasion to see one of THOSE a few years back. 5000 gallons or so of gasoline poured down a storm drain, under a highway, and into a drainage canal behind a subdivision. It looked like a preview of hell, the air was black, the sky was orange, trees were burning, and there were over 50 fire combo units all sitting there trying to contain the fire. Jon |
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DT wrote: Actually quite real. Nitrogen supercools tarmac. Oxygen condenses on tarmac, soaks in. Tarmac goes boom as it warms up, or a fly lands on it. Oh, yeah! LOX condensation can cause some very strange events. Jon |
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DT wrote: Actually quite real. Nitrogen supercools tarmac. Oxygen condenses on tarmac, soaks in. Tarmac goes boom as it warms up, or a fly lands on it. Interesting, although I don't recall any warnings about this in all my years of working with cryogenics, though. LN2 isn't all that much colder than the condensation temperature of oxygen (-270 F) but if the tarmac got to full LN2 temp (-320 F) it could work. Certainly LN2 doesn't cause oxygen to condense appreciably in typical lab conditions. We made experimental quantities of LOX with just LN2 in our lab, to demonstrate the paramagnetic effect of LOX. I think we just filled a thin-walled metal container (part of a nitrogen trap) with a couple hundred cc's of LN2, and placed an insulated container below it to catch anything that dripped off. We then poured the captured liquid off, and it was repelled by a magnet. It was also clearly a blue color. I have a friend who works on medical MRI magnets. When they have a magnet quench, it blows the burst diaphragm. The liquid helium is almost immediately vaporized, although you could arque that there are structures inside the magnet that would still be near 4 K. Condensation of Oxygen in the opened dewar is a serious safety problem, and they have to use vacuum pumps with special silicone oil, as the pumping of gases containing too much oxygen can cause a truly spectacular explosion of petroleum-based oil in vacuum pumps. Jon |
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Rick wrote: Roy wrote: Well you could always get nitrogen nacosis. Not at 1 atmosphere. Suffocation could be a concern. -- -- Mark N.E. Ohio Never argue with a fool, a bystander can't tell you apart. (S. Clemens, A.K.A. Mark Twain) When in doubt hit the throttle. It may not help but it sure ends the suspense. (Gaz, r.moto) |
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Jon Elson wrote: (clip) While the release of tons of liquid Nitrogen onto a road would not technically be an explosion, it could still release a HUGE amount of gas pretty suddenly. I sure wouldn't want to be anywhere near it if the tank cracked or if a safety relief valve that happend to be under the liquid level was forced to open.(clip) ^^^^^^^^^^^^^ I sure wouldn't stand around gawking. It seems to me the real danger from this "explosion" would not be nitrogen narcosis or asphyxiation, but frostbite or outright freezing. How would you like to be in the path of an expanding, boiling mass of liquid nitrogen? |
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Hey DT,
Wow!! That's amazing! What sort of relative humidity would there be in the area. I would have thought that as the exterior surfaces of the flex line began to cool, that it would form a heavier and heavier layer of "ordinary" frost from the ambient room air. Is the LOX taken from that frost? Or some other action? I guess if the frost built to the point that it fell off, or the flex "flexed" and knocked it off, then it would expose the super-cold surface directly. Pretty interesting. As a gruesome aside to what started this thread...many years ago near Hamilton, Ontario, a semi-trailer tanker, with a tank diameter of only about 5 feet, was rounding a corner too fast and rolled over onto its side. It had a smallish cat-walk at the tank top around the filler cap, which "hung out" from the tank top, due to the small diameter of the tank. When the truck rolled, this cat-walk ended up laying right into the passenger seat of a convertible car that was alongside. The lady passenger was killed instantly, and other than the seat back being pushed flat back, there was not so much as a scratch or a mark on the rest of the car, not even the dash-board. How come I always remember these gruesome bits?? Take care. Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXXXXXXXXXX On 17 Dec 2003 21:09:57 GMT, (DT) wrote: Actually quite real. Nitrogen supercools tarmac. Oxygen condenses on tarmac, soaks in. Tarmac goes boom as it warms up, or a fly lands on it. Interesting, although I don't recall any warnings about this in all my years of working with cryogenics, though. LN2 isn't all that much colder than the condensation temperature of oxygen (-270 F) but if the tarmac got to full LN2 temp (-320 F) it could work. Certainly LN2 doesn't cause oxygen to condense appreciably in typical lab conditions. Now, chilling from liquid hydrogen definitely does it. On un-insulated flex lines, the LH2 (at -420 F) would condense oxygen and nitrogen directly out of the air, and it would actually 'rain' in the vicinity of the LH2 lines. The LN2 tended to gas off fairly quickly, leaving it LOX enriched. If the droplets of liquid air hit grease, you got little *poofs* as they ignited. Note, temperatures are from memory, I don't have a chart handy. DT |
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In article , Leo
Lichtman says... I sure wouldn't stand around gawking. It seems to me the real danger from this "explosion" would not be nitrogen narcosis or asphyxiation, but frostbite or outright freezing. How would you like to be in the path of an expanding, boiling mass of liquid nitrogen? I suppose this really belongs in the shop pranks but... A co-worker had purchased a brand new pair of safety shoes from the shoe van that comes around to work periodically. Later that day he was filling an LN2 tank and the boil-off was dripping on the floor, and froze his shoes. When he went to walk away, the soles cracked - right across the insteps. The van had not left yet for the day, so he went back there and said "hey, look what happened to these brand new shoes!" "Oh my god, that must be some kind of manufacturing defect" was the response, and they gave him a brand new pair of shoes in exhange for the 'defective' ones. Another fun-n-games is to wait until the mark is about to re-enter his office - and pour a couple of quarts of LN2 into his chair. The look when he comes in and finds his seat cushion frosted and smoking is amazing. Reverse hot-foot if you will. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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In article . net, Rick says...
Well you could always get nitrogen nacosis. Not at 1 atmosphere. Well maybe if the tank hit one on the head... Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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In article , Brian Lawson says...
Wow!! That's amazing! What sort of relative humidity would there be in the area. I would have thought that as the exterior surfaces of the flex line began to cool, that it would form a heavier and heavier layer of "ordinary" frost from the ambient room air. Really cold exposed transfer lines don't really frost from water vapor, the amount of gas condensing on them seems to prevent that. Basically they just get 'wet' looking and start dripping. Obviously when one is transferring cryogenic fluids for real the use of a flexible vacuum-insulated transfer stick is required. The good story I read about the apollo rocket program was that the engines were all tested on the ground, and the exposed flex lines would frost up to a large degree. The frost provided significant mechanical damping to the stainless bellows lines. The second time the rocket was flown, an engine failed because the flex line had a resonant oscillation, and fatigued during operation, and fractured open. Dampers were added. Note, temperatures are from memory, I don't have a chart handy. Appx boiling points of: LO2: 90K LN2: 77K Liq Neon: 27K LH2: 20K LHe-4: 4K LHe-3: 3.5K Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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Tanker accident
On Wed, 17 Dec 2003 16:16:16 -0500, Tom Quackenbush
wrote something .......and in reply I say!: I guess the double post of the statement makes up for the post of a null statement? GG On 17 Dec 2003 18:07:05 GMT, (ERich10983) again wrote: ************************************************** ** sorry remove ns from my header address to reply via email I was frightened by the idea of a conspiracy that was causing it all. But then I was terrified that maybe there was no plan, really. Is this unpleasant mess all a mistake? |
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Jon Elson wrote: (clip) Oh, yeah! LOX condensation can cause some very strange events. ^^^^^^^^^^^ At the Shell Chemical plant in Martinez, where they make ammonia (NH3), they had a lot of liquid oxygen, and no use for it, so they just let it evaporate in an open tank. People used to throw in candy bars, etc, just to see the fireworks, so the company had to put a cover over the tank. |
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On 18 Dec 2003 05:17:38 -0800, jim rozen
brought forth from the murky depths: In article . net, Rick says... Well you could always get nitrogen nacosis. Not at 1 atmosphere. Well maybe if the tank hit one on the head... Wouldn't that be "Nitrogen KnockOutsis"? ================================================== ======== Save the + http://www.diversify.com Endangered SKEETS! + Web Application Programming ================================================== ======== |
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In article , Larry Jaques says...
Wouldn't that be "Nitrogen KnockOutsis"? Hmm. Nitrogen Knock-out-O-sis! LOL. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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In article , DT says...
Yep, I've seen it happen also. I guess the average citizen is pretty shocked to think of people walking around in a cloud of *damn* cold nitrogen with liquid on the floor, but we did it all the time. Ha ha. I was putting some LN2 into a small hand dewar one time, outside a co-workers's lab. I made the comment to him that the LN2 worked *great* at removing floor tiles and he said that was bull****, it would never do that. So I simply poured a small steady stream onto the floor and sure enough that tile fractured into a hundred pieces and the mastic let loose on about half of them. You should have heard the crying and wailing, "look what you just did to the floor outside *my* lab!!" They actually removed the accumulated paint from the inside of the statue of liberty using LN2 - stripped it all off without damaging the already-fragile iron armature inside of the copper skin. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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On Thu, 18 Dec 2003 02:45:42 GMT, Rick
wrote: ===Roy wrote: === === Well you could always get nitrogen nacosis. === ===Not at 1 atmosphere. === ===Rick Yep I guess your right, nothing there to apply sufficient prressure to make you saturated with it. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
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There have been several replies about LN2 in industrial settings that
imply that LN2 does instantly vaporize when spilled. Yes? In that case, a tanker spill wouldn't represent an explosion danger - there's not enough heat available to vaporize it fast enough to be explosive. Just an observation. Bob |
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"Bob Engelhardt" wrote in message ... There have been several replies about LN2 in industrial settings that imply that LN2 does instantly vaporize when spilled. Yes? In that case, a tanker spill wouldn't represent an explosion danger - there's not enough heat available to vaporize it fast enough to be explosive. Just an observation. Bob True to a point...except that the LN2 is under ALOT of pressure and if the tank itself fails, it would get ugly very fast. So it's not a true "explosion" in the chemical sense, but shrapnel from a hand gergade doesn't care what made it go boom, just that it went boom. Mike |
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What pressure would nitrogen have to be stored at to be liquid at room
temperature anyway? Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms "The Davenports" wrote in message ... True to a point...except that the LN2 is under ALOT of pressure and if the tank itself fails, it would get ugly very fast. So it's not a true "explosion" in the chemical sense, but shrapnel from a hand gergade doesn't care what made it go boom, just that it went boom. |
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On Fri, 19 Dec 2003 23:29:13 -0600, "Tim Williams" wrote:
What pressure would nitrogen have to be stored at to be liquid at room temperature anyway? It can't. The critical temperature for nitrogen is -232.5 F. Pressure alone won't keep nitrogen liquid above the critical temperature. Gary |
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Tim Williams wrote:
What pressure would nitrogen have to be stored at to be liquid at room temperature anyway? Tim Atmospheric seem to fine for all the liters we hauled around in the chem. dept. :-) ...lew... |
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"Lewis Hartswick" wrote in message
... What pressure would nitrogen have to be stored at to be liquid at room temperature anyway? ^ ^ ^ ^ ^ ^ ^ Atmospheric seem to fine for all the liters we hauled around in the chem. dept. :-) Erm... read closer :^) Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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It's just kept cold, in a dewar.
Steve R. "Tim Williams" wrote in message ... What pressure would nitrogen have to be stored at to be liquid at room temperature anyway? Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms "The Davenports" wrote in message ... True to a point...except that the LN2 is under ALOT of pressure and if the tank itself fails, it would get ugly very fast. So it's not a true "explosion" in the chemical sense, but shrapnel from a hand gergade doesn't care what made it go boom, just that it went boom. |
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"Gary Coffman" wrote in message
... It can't. The critical temperature for nitrogen is -232.5 F. Pressure alone won't keep nitrogen liquid above the critical temperature. Hmmm... why? Tim (never took a gas physics class) -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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On Sun, 21 Dec 2003 00:49:25 -0600, "Tim Williams" wrote:
"Gary Coffman" wrote in message .. . It can't. The critical temperature for nitrogen is -232.5 F. Pressure alone won't keep nitrogen liquid above the critical temperature. Hmmm... why? Because that's what the definition of critical temperature for gases means. Basically, the intermolecular forces between nitrogen molecules (due primarily to asymmetric charge distribution in the individual molecules) aren't that strong. That's because of the particular electronic structure of the nitrogen atom and the particular covalent bond angle of the diatomic molecule. The magnitude of the forces trying to break those weak intermolecular bonds increases with temperature. Shoving them closer together with pressure isn't enough, above the critical temperature, to get them to stay in the liquid state because the pressure alone can't compensate for thermal agitation, ie the force vectors don't line up in opposition often enough to cancel out throughout the bulk of the material. Gary |
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On 18 Dec 2003 05:04:41 -0800, jim rozen said: In article , Leo Lichtman says... I sure wouldn't stand around gawking. It seems to me the real danger from this "explosion" would not be nitrogen narcosis or asphyxiation, but frostbite or outright freezing. How would you like to be in the path of an expanding, boiling mass of liquid nitrogen? I suppose this really belongs in the shop pranks but... A co-worker had purchased a brand new pair of safety shoes from the shoe van that comes around to work periodically. Later that day he was filling an LN2 tank and the boil-off was dripping on the floor, and froze his shoes. When he went to walk away, the soles cracked - right across the insteps. The van had not left yet for the day, so he went back there and said "hey, look what happened to these brand new shoes!" "Oh my god, that must be some kind of manufacturing defect" was the response, and they gave him a brand new pair of shoes in exhange for the 'defective' ones. So you think it's funny that someone cheated the shoe salesman and someone else had to pay for his own carelessness? Another fun-n-games is to wait until the mark is about to re-enter his office - and pour a couple of quarts of LN2 into his chair. The look when he comes in and finds his seat cushion frosted and smoking is amazing. Reverse hot-foot if you will. Jim You're about as funny as a fart at a funeral. |
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