LN2 Usage - Need Help

H

Heli00

Joined
Oct 19, 2017
Messages
325
Hi again,

I ordered a Dewar, 10L with a 2” opening for cryo of AEB-L, 440C and A2. Is the 10L enough, or should I have ordered the 20L?

Does the blade have to be completly submerged in the liquid? What if it is only submerged half way? What if it doesn’t even touch the liquid? What is proper?

Of course, the blade will be completely inside the dewar and the cap on.

Thanks in advance,
Constantin
 
A quick search would show at least 5 LN threads on your subject in the last month or so.

10L will work, but the tank life will be shorter.
The knife does not have to be submerged. Actually, hanging the knife vertically from a stainless hook/wire is a better method.
 
Stacy E. Apelt - Bladesmith said:
A quick search would show at least 5 LN threads on your subject in the last month or so.

10L will work, but the tank life will be shorter.
The knife does not have to be submerged. Actually, hanging the knife vertically from a stainless hook/wire is a better method.
Click to expand...

Sorry Stacy, I got impatient and didn't search, just ordered the dewar literally minutes before posting. So I was wondering if I should have gotten the 20L, before they shipped.
 
JTknives said:
Where are all these dewar threads coming from?
Click to expand...

JT, I'm sure I will be using your services in the future, I just want to learn for now.
thanks.
Stacy E. Apelt - Bladesmith said:
A quick search would show at least 5 LN threads on your subject in the last month or so.

10L will work, but the tank life will be shorter.
The knife does not have to be submerged. Actually, hanging the knife vertically from a stainless hook/wire is a better method.
Click to expand...

So in a 10L dewar, or any other volume, the liquid is not to the throat, correct? Is it maybe a quarter of the container or so?

Thanks again,
Constantin
 
I use a 10L, I submerge. No snap temper, just go after quench.


You'll be fine with the 10L, You'll just have to refill more often.

It's $3 per Liter In my area and I just drive to get a refill.

Some folks have a delivery refill set up so they can save money with having a larger Dewar and it will last longer.

I would still prefer the 10L and save money to buy other tools in the shop.
 
Stacy E. Apelt - Bladesmith said:
A quick search would show at least 5 LN threads on your subject in the last month or so.

10L will work, but the tank life will be shorter.
The knife does not have to be submerged. Actually, hanging the knife vertically from a stainless hook/wire is a better method.
Click to expand...

Stacy E. Apelt - Bladesmith Stacy E. Apelt - Bladesmith , Just looked at some other related posts you've mentioned, but I still don't have the answer.

My question still to be answered is, when you fill up a dewar, where is the liquid level at?

The answer to this will tell me if the blade ends up in the liquid or just suspended on top of it. I guess this is my main question and could not find the answer in the searched posts, unless I missed it, please point me to the specific thread.

Thanks,
 
Last edited:
DeadboxHero said:
I use a 10L, I submerge. No snap temper, just go after quench.


You'll be fine with the 10L, You'll just have to refill more often.

It's $3 per Liter In my area and I just drive to get a refill.

Some folks have a delivery refill set up so they can save money with having a larger Dewar and it will last longer.

I would still prefer the 10L and save money to buy other tools in the shop.
Click to expand...

Thank you!
 
A full Dewar is just that - FULL. It is filed to just below the neck. If you wanted a heigth, I'd say it is about 3/4 the Dewar height. As the LN evaproates, the level drops. The inside of Dewar is still at the same temperature until the last of the LN is gone.
 
Heli00 said:
Hi again,

I ordered a Dewar, 10L with a 2” opening for cryo of AEB-L, 440C and A2. Is the 10L enough, or should I have ordered the 20L?

Does the blade have to be completly submerged in the liquid? What if it is only submerged half way? What if it doesn’t even touch the liquid? What is proper?

Of course, the blade will be completely inside the dewar and the cap on.

Thanks in advance,
Constantin
Click to expand...

Where did you get a 10l dewar with a 2in neck????
 
Heli00 said:
Stacy E. Apelt - Bladesmith Stacy E. Apelt - Bladesmith , Just looked at some other related posts you've mentioned, but I still don't have the answer.

My question still to be answered is, when you fill up a dewar, where is the liquid level at?

The answer to this will tell me if the blade ends up in the liquid or just suspended on top of it. I guess this is my main question and could not find the answer in the searched posts, unless I missed it, please point me to the specific thread.

Thanks,
Click to expand...

Mine usually overflows when they fill it. I push the lid in and the rest runs out onto my feet, causing chilly toes. It's not a propane tank, it doesn't need room for expansion.
 
Stacy E. Apelt - Bladesmith said:
A full Dewar is just that - FULL. It is filed to just below the neck. If you wanted a heigth, I'd say it is about 3/4 the Dewar height. As the LN evaproates, the level drops. The inside of Dewar is still at the same temperature until the last of the LN is gone.
Click to expand...

So if I understand you correctly, if the knife is tottaly submerged in the liquid, or not at all, just maybe 2" of LN2 on the bottom of the dewar, the same temperature is reached.

Therefore regardless of the ln2 level in the dewar, the knife will be cryoed at the same temperature, and there will be no difference in the results, correct?

Thanks again,
Constantin
 
Heli00 said:
So if I understand you correctly, if the knife is tottaly submerged in the liquid, or not at all, just maybe 2" of LN2 on the bottom of the dewar, the same temperature is reached.

Therefore regardless of the ln2 level in the dewar, the knife will be cryoed at the same temperature, and there will be no difference in the results, correct?

Thanks again,
Constantin
Click to expand...
Correct
 
Mostly correct,

there is a temperature difference between the liquid and foam plug. It’s not much but it’s there. I think the study I read said that it was -300° under the plug.
 
I've actually measured the temperature inside my LN2 container, it's a 25 liter pretty basic Taylor-Wharton LD25. I use it until it's more or less completely out of LN2.

During this measurement the probe is hanging just below the neck of the container, and it's only a couple of inches of LN2 left at the bottom of the container.

qILnxVB.jpg
 
Stromberg Knives said:
I've actually measured the temperature inside my LN2 container, it's a 25 liter pretty basic Taylor-Wharton LD25. I use it until it's more or less completely out of LN2.

During this measurement the probe is hanging just below the neck of the container, and it's only a couple of inches of LN2 left at the bottom of the container.

qILnxVB.jpg
Click to expand...

Cool, thanks!

So here is my dilemma. I bought the 10L version, but now I see that with longer knives, part of the handle is protruding inside the neck, maybe half way. Would it be cold enough inside the neck. The cap will be sticking half way up with these longer blades.

Would that be ok?

Thanks again,
Constantin
 
It will work. The handle/tang area may still have some RA, but that isn't a bad thing. Toss a piece of ins-wool over the top while the blade is in the cryo.
You could also make a custom cap from styrofoam or other foam that had a slot in it. That would only allow the blade to slide in and keep the opening to a minimum.
 
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