Tanker accident

snipped-for-privacy@aol.com (ERich10983) wrote in news: snipped-for-privacy@mb-m26.aol.com:

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?

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.

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'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 know that NE Vermont roads are very bad right now. Freezing rain as bad as I've seen in 5 years. You know it's bad when you drive with

R, Tom Q.

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

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 know that NE Vermont roads are very bad right now. Freezing rain as bad as I've seen in 5 years. You know it's bad when you drive with

R, Tom Q.

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

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 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!

On 17 Dec 2003 18:07:05 GMT, snipped-for-privacy@aol.com (ERich10983) brought forth from the murky depths:

Well, that's ONE thing the Shrub won't be able to blame on Hussein.

-- Remember: Every silver lining has a cloud. ----

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 ==================================================

Never seen, or seen evidence of, a liquid nitrogen explosion ? It's comparably energetic to propane.

LN2 is generally shipped in a vacuum insulated vessel. After an impact there's a risk that the two shells are put in contact, or the vacuum may be lost. This is a big heat leak, big enough to boil liquid into vapour and cause an overpressure accident. Although there are blow-out disks etc., if something like a road tanker turns over, then these may either be blocked, or may leak and then block themselves by freezing groundwater into an ice plug.

-- Smert' spamionam

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:

Not at 1 atmosphere.

Rick

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

Oh, yeah! LOX condensation can cause some very strange events.

Jon

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

Suffocation could be a concern.