Liquid Nitrogen use and storage

It really doesn't help carbon steel much,but is benificial on D2 mostly use it on SS.
Does wonders for improving 440-C and ATS 34.
Stan
 
Well that answered alot of questions. Now for the next thing. Is it possible to make a storage container that will work. Right now funds are tight.
 
It would be very difficult to make an appropriate container, I would think. A LN dewar is basically two layers with a gap between that has a vacuum pulled on it. A vacuum is a VERY good insulator as energy has nothing to pass through. They are very precisely made containers.

Check around Craig's list and ebay or keep an eye out on for-sale forums. I found mine through a guy on Bladeforums who works in a genetics engineering lab. He sold a batch of 6 dewars, and I was able to pick one up. It's an 8 week dewar and will hold a charge for at least the two months its rated for. They're used quite a bit in the cattle industry.

--nathan
 
SBuzek said:
...
Does wonders for improving 440-C and ATS 34.
Stan
Click to expand...

These steels are what I've used Dry Ice on.
But I didn't get a block, I got the pellets.

I bought 3 of those styrofoam coolers, put 2 of them together for the Treatment and wrapped them in Insulation Board(lasts for 2 weeks), and the other for dumping some of the pellets into so I can get my blades farther down in the container, then pour the rest of the pellets over them.
2thumbs
 
Bit the bullet and got a 20L dewar.

I'm looking forward to getting it filled and doing some LN cryo!

BC
 
We got a dewar when we started heat treating CPM S30V and couldn't do without it. I think is ran about $280.00. Some of the necks of the dewars are small in diameter and you will need room to get blades in and out. Ours is about 3 inches wide and seems to work fine. The Liquid Nitrogen last for several months. One thing that should be mentioned is the welding supply places around here won't fill the dewar if you can't carry it outside the vehicle. Like in the back of a truck instead of in a car. Trying to breathe 100% nitrogen is not very good for you and I guess they are watching out for those that won't watch out for themselves.
 
One safety fact that needs mentioning , for any of the guys thinking about making or using something other than a real Dewar to carry LN

DO NOT .......I repeat, DO NOT use a container that has an airtight cap or top.

LN produces gas as it "boils off". It can and will reach pressure that will turn a sealed container into a truly explosive container. It can/will kill you if you are in the vicinity when it explodes. Not if it explodes ............. when it explodes

I've seen guys on other forums say that you can use a regular thermos bottle like you carry your coffee to work in. Maybe so, but you would have to leave the cap loose enough to allow for the gas to bleed off without creating any pressure whatsoever. I would say, don't do it

Seriously, get a real Dewar or use Dry ice with Kero, Alcohol or Acetone.


cool 1
 
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I was just looking through the ebay listings and I was sort of getting a laugh from some of the crap they are trying pull off but I'm thinking this might be one of the worst I've seen so far: http://cgi.ebay.com/Liquid-Nitrogen...in_0?hash=item4399f5408f&_trksid=p3286.c0.m14

Is that yellow electrical tape wrapped around the insulation (that he says is in real good condition)? Where is the lid?

Hmmm, I just ran across another one with tape around it and no lid, I guess thats the norm for a dewar flask :(

Maybe this one will work: http://cgi.ebay.com/DEWARS-12-STAIN...in_0?hash=item1c048d1284&_trksid=p3286.c0.m14
 
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Could one not make a vessel with two steel pipe pieces of different size? Weld bottoms onto the pieces of pipe, make 1 pipe one inch larger diameter, insert smaller pipe into larger, make a ring to fit both and weld together. drill hole and solder/braze in a piece of pipe like 1/4" copper water pipe long enough that you can attach a vacuum pump and crimp it off when the vacuum is attained. Draw vacuum and crimp pipe.

Figure 2 in this paper: the cryogenic treatment of tool steels Seems to suggest that leaving D2 in the cryo for longer than 38 minutes causes a reduction in hardness.
 
Steve_G said:
Could one not make a vessel with two steel pipe pieces of different size? Weld bottoms onto the pieces of pipe, make 1 pipe one inch larger diameter, insert smaller pipe into larger, make a ring to fit both and weld together. drill hole and solder/braze in a piece of pipe like 1/4" copper water pipe long enough that you can attach a vacuum pump and crimp it off when the vacuum is attained. Draw vacuum and crimp pipe.

Figure 2 in this paper: the cryogenic treatment of tool steels Seems to suggest that leaving D2 in the cryo for longer than 38 minutes causes a reduction in hardness.
Click to expand...

I'm planning on doing it. Most people don't have the equpt to make it. And like DW said you can't make it airtight cap the CO2 has to be able to bleed off.
 
Seems to me, depending on how much volume you require, that a 20# or 30# propane tank would be perfect for the outside shell. A 6" - 8" pipe with a bottom welded on for the LN container. Slide that into a hole cut in the top of the propane tank with 3"-4" sticking out for a good insulated cap to be placed on then weld the pipe into the tank. I'm sure if one called around, you could probably find somebody to pull the vacuum for you, HVAC repair companies come to mind.
 
Just off the top of my head I would think that as liquid nitrogen warms up and reverts from a liquid state to a gas that it would be nitrogen. It's been a long time since I took chemistry so it should be understandable that I might have a problem understanding this, but how does liquid nitrogen convert to CO2?
 
I was wondering the same thing myself.

One thing for certain is that dry ice will give off carbon dioxide as it evaporates.
 
Something to think about is that most of the places that have liquid Nitrogen for sale wont sell it if it's not going in an appropriate container. The stuff is dangerous if the right precautions aren't taken. Just ask them Aggies what happens when you don't use the right equipment for storing Liquid Nitrogen.
 
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Rusty McDonald said:
Something to think about is that most of the places that have liquid Nitrogen for sale wont sell it if it's not going in an appropriate container. The stuff is dangerous if the right precautions aren't taken. Just ask them Aggies what happens when you don't use the right equipment for storing Liquid Nitrogen.
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You make a very good point.
 
Mathsr said:
Just off the top of my head I would think that as liquid nitrogen warms up and reverts from a liquid state to a gas that it would be nitrogen. It's been a long time since I took chemistry so it should be understandable that I might have a problem understanding this, but how does liquid nitrogen convert to CO2?
Click to expand...

My Bad Harry :eek: You are correct. It's dry ice that boils off as CO2, Not LN

Hey, it was early, unsure and I had only taken a few sips of coffee :rolleyes:

:eek: :eek:

I edited my post to correct my mistake.

Thank you for pointing it out ...............

Still, there are very explosive results when sealing LN in an airtight container.
I think I read the same report as Rusty referred to, where the LN container went through several floors of a building when it exploded


;)
 
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David it was a good point to make. A liter of LN converts to about 25 cubic feet of gas. A huge volume difference. In a container that can't contain the pressure it could be explosive and dangerous.
 
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