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

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.

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

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

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.

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

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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

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.

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

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

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

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In article ,
says...

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.


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

(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?

--
John Snow
"If I knew what I was doing, I wouldn't be here"

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

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?

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

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In article , says...

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

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.


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

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.

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

On 17 Dec 2003 18:07:05 GMT, (ERich10983) brought
forth from the murky depths:

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.....

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

--
Remember: Every silver lining has a cloud.
----
http://diversify.com Comprehensive Website Development

On 17 Dec 2003 18:07:05 GMT, (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!

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!
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Roy wrote:

Well you could always get nitrogen nacosis.

Not at 1 atmosphere.

Rick

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)

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

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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"?


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In article , Larry Jaques says...

Wouldn't that be "Nitrogen KnockOutsis"?

Hmm. Nitrogen Knock-out-O-sis!

LOL.

Jim

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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.

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