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Topic: liquid nitrogen vs. thermos  (Read 26857 times)

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Offline vmelkon

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liquid nitrogen vs. thermos
« on: March 25, 2010, 08:47:23 PM »
What would happen if you had had one of those glass dewars made by Thermos at 20 C and you poured LN2 in it. Would it crack?

Offline AWK

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Re: liquid nitrogen vs. thermos
« Reply #1 on: March 26, 2010, 04:56:10 AM »
Sometimes. Chemist generally use glass dewars for small amounts of liquid nitrogen (up to a few liters)
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Offline eadt

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Re: liquid nitrogen vs. thermos
« Reply #2 on: March 27, 2010, 03:36:32 PM »
Hi there I'm really interested in that question, I've a termo for coffee similar to this one:

It's like 1,5L capacity, and I wonder if I could put LN2 into it and put it in the freezer. Would it last for 7 days or something like that? Would I've to left the termo open? (I ask because I've seen people putting LN2 into a closed bottle and puting it into a pool, and the bottle explodes).

Offline Borek

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Re: liquid nitrogen vs. thermos
« Reply #3 on: March 27, 2010, 04:39:05 PM »
No idea how long it will last. You can't close it tight, gas must be able to escape.
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Offline eadt

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Re: liquid nitrogen vs. thermos
« Reply #4 on: March 27, 2010, 05:55:46 PM »
Ok, so if I left it a bit opened, at -20ÂșC in the freezer and with some kind of blanket around (leaving air ot get out) what do you think, more or less, 4-5 days?

Offline billnotgatez

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Offline skyjumper

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Re: liquid nitrogen vs. thermos
« Reply #6 on: March 28, 2010, 05:48:35 PM »
According too my Flinn Scientific catalog and reference, 2009
"How long can liquid nitrogen be stored in a Dewar flask? Our best estimate is that a GOOD 1000 ml Dewar flask will lose approximately 500 mL for every 24 hour period stored. The larger the Dewar Flask the slower the loss rate.

I doubt your thermos will even come close to that. The same reference also warns against over tightening causing an explosion in a standard thermos, and that it is very likely for any plastics on the thermos to crack due to the temp. decrease N2 (lq) produces.

In case you were wondering, The prices for a Dewar flask from Flinn are:1000mL 119.00
1900mL 277.
d4l (with .4L a day loss) 638.35
and 10L with .22L loss a day: 808.35.

Flinn Chemical and Biological Catalog Reference manual 2009 Pp237-238

Offline Borek

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Re: liquid nitrogen vs. thermos
« Reply #7 on: March 28, 2010, 05:50:12 PM »
One more thing - I think steel termo can become so cold on the outside that it can be dangerous to touch with bare hand.
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Offline Grundalizer

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Re: liquid nitrogen vs. thermos
« Reply #8 on: March 28, 2010, 06:35:14 PM »
We just bought two, 200$ 1 or 2 L Dewars, high quality, from Nalgene, and they only last 6 hours max when filled.  No way you'll get 4-5 days

Offline billnotgatez

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Re: liquid nitrogen vs. thermos
« Reply #9 on: March 29, 2010, 02:18:37 AM »
I know they transport liquid nitrogen on rail cars but i have no idea on what the loss rate is during the long trips.

Offline skyjumper

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Re: liquid nitrogen vs. thermos
« Reply #10 on: March 29, 2010, 08:39:55 PM »
I can't imagine that they loose that much. If a 10 ltr. loses .22l a day, when we get into the hundreds of liters it has to be less.

Offline silenceisgod

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Re: liquid nitrogen vs. thermos
« Reply #11 on: March 31, 2010, 11:43:09 PM »
Would insulation make any difference? Styrofoam wrapped in a space blanket in the freezer makes all the difference with dry ice, for me.

Offline skyjumper

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Re: liquid nitrogen vs. thermos
« Reply #12 on: April 01, 2010, 09:39:40 PM »
With the temps that low, I cant imagin it making a world of difference. A Dewar flask has a vacuum between the inside and outside, NOT insulation (it attempts to stop thermal conductivity between the liquid and the rest of the world) Now, some thermoses per wikipedia use this technology (apparently the expensive Thermos brand ones) but I cant imagine the vacuum being as strong as say, a professional one.

Offline Grundalizer

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Re: liquid nitrogen vs. thermos
« Reply #13 on: April 01, 2010, 09:51:07 PM »
I think this calls for some science.  Tomorrow I'm going to go buy a regular coffee thermos...fill it with liquid nitrogen, and place the cap loosely over the top.  Then we shall see how long it lasts if it doesn't implode or something crazy.


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