Tanker accident

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

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Well maybe if the tank hit one on the head...

Jim

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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.

Appx boiling points of:

LO2: 90K LN2: 77K Liq Neon: 27K LH2: 20K LHe-4: 4K LHe-3: 3.5K

Jim

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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?

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?

You are correct, as normal ice builds up, it insulates the LH2 line from the air and the liquification of the air stops. This was in a high performance rocket engine test stand (I work for NASA) and the final fuel lines to the engine were just plain flex lines. Each time the engine fired it tended to shake off the frost and re-expose the bare metal line to some extent.

As an interesting note, we ran some low pressure LOX transfer lines uninsulated for dozens of feet at a time, -297 F just isn't cold enough to worry about at times. But the final LOX lines out of the high pressure tank ran in open LN2 troughs to supercool the LOX. In fact the entire high pressure LOX tank was submerged in LN2. We always watched the LN2 to see if it turned blue, indicating a LOX leak into the LN2 bath.

Further note: The LOX and LH2 systems were running at 3000-4000 psi!!

DT

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.

DT

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.

On 18 Dec 2003 05:17:38 -0800, jim rozen brought forth from the murky depths:

Wouldn't that be "Nitrogen KnockOutsis"?

========================================================== Save the +

Hmm. Nitrogen Knock-out-O-sis!

LOL.

Jim

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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 bullshit, 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

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Yep I guess your right, nothing there to apply sufficient prressure to make you saturated with it.

Visit my website:

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

So you think it's funny that someone cheated the shoe salesman and someone else had to pay for his own carelessness?

You're about as funny as a fart at a funeral.

Once an asshole, always an asshole.

On Sun, 21 Dec 2003 14:26:24 -0800, Ken Davey whined:

Yup

Cute. Got any more addresses to let you get in the last word?