Deep freeze with CO2 fire extinguisher?

S

Scaniaman

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Jun 15, 2012
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Hi

I've doing a bit of thinking and reading on the subject of deep freezing SS, trying to figure out a reasonable set up for a hobbyist (me). It's bit of a hazzle for me to get dry ice and LN2, and I'd probably only do a blade every month or two at the most as thing are now.
Different steel producers (for example Sandvik) say that you only have to reach temp and not neccesarily soak at -109 F / - 78 C. I was chatting with this knifemaker and he said he used a CO2 fire extinguisher to deep freeze his blades in CPM154, Rwl 34 etc...

It seem like a rather practical way to go about it when you're only doing one blade every now and then like me (easy storage, easy refill, no messing with dryice/alcohol). I was thinking purpose built small styrofoam box for the blade, then go at it with the spray...

Any thought on this? You think I'd get rid of enough of the RA in steel?
 
I don't see how it would be any cheaper than dry ice/alcohol. Both are pretty cheap and you can just pour the alcohol back into its container once the dry ice evaporates.
Pretty sure once you pull the pin and use a fire extinguisher once, that's all she wrote. I'd be surprised if it worked a month later. The more expensive ones can be refilled, but I wouldn't call it cheap.
 
E.Carlson said:
Pretty sure once you pull the pin and use a fire extinguisher once, that's all she wrote. I'd be surprised if it worked a month later. The more expensive ones can be refilled, but I wouldn't call it cheap.
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You're thinking of dry chemical extinguishers. CO2 works repeatedly.
 
A blast of CO2 would not cool a blade to -100F. The DI "snow" is sublimation into CO2 gas almost instantly. A block of DI costs about $5. A can of alcohol costs $15. The alcohol will last years. I don't recall what a CO-2 fill and inspection costs, but I bet its a lot more than $5.
 
Not that I disagree, but it costs me an hour's drive (round-trip), $5 in gas, and $15 in dry ice every time. Can't buy less around me.
I've been thinking about investing in a dry ice maker. Probably would have paid for itself by now.
 
daizee said:
Not that I disagree, but it costs me an hour's drive (round-trip), $5 in gas, and $15 in dry ice every time. Can't buy less around me.
I've been thinking about investing in a dry ice maker. Probably would have paid for itself by now.
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I am kind of in the same situation. Dry ice maker huh? Interesting. How much dry ice is typically needed for a single say 5" blade?
 
So two of these 9 oz pieces would do it. The thingy is $ 250-300. Then there is the cost for the tank of course. From a 50 lb tank you get appr 20 pieces, so 10 occations of deep freeze. That's about a year of knifemaking for me, probably closer to one and a half. But including the cost of the gas tank, you are well in the neighbourhood of a good LN2 dewar...The advantage would be you don't have to worry about evaporation and refilling regularily...

 
Most grocery stores, including your local Walmart or Costco, should be able to give you a few lbs of dry ice for almost nothing. If you have any grocery delivery services nearby, they'll almost certainly have it as well. I can't imagine blowing off a fire extinguisher will be all that efficient, and even if it were, it's gonna be more expensive than the $5 you pay for a couple lbs of dry ice. Buying some $300 contraption seems like a bit of overkill as well, just to pump out a few pucks of ice every once in a while. You can get 5lb bricks of the stuff from the grocery.
 
One problem with not filling out your profile is we don't know where you live.
Many people who say they can't get something merely don't know where to look. Posting your city and state and country will help us help you. Recently I showed a fellow who couldn't find DI that a RV supplier had it the next town over … a 15 minute drive.
 
I’ve been playing around with coolant sprays like MG super freeze and even canned air dusters. They are supposed to be able to cool to -60.

A few years ago I compared dry ice and MG superfreeze. I tested the hardness in D2 and there wasn’t a detectable difference. I am just using a handheld tester that is hard to delineate anything less than about a point of hardness. I’d only expect to get maybe two smaller knives out of a can of superfreeze and that costs about 16 or 17 bucks. Maybe makes sense for a single knife heat treat when doing one a month or something. Definitely not for a batch.

I would need a bit more testing to be confident in using a coolant spray, but it might be something to consider. Certainly more expensive than dry ice, but less than a dry ice making set up.

I still use dry ice, generally and wouldn’t use the coolant spray on something I was going to sell without more testing.

CO2 cartridges might be something to consider.
 
Stacy E. Apelt - Bladesmith said:
One problem with not filling out your profile is we don't know where you live.
Many people who say they can't get something merely don't know where to look. Posting your city and state and country will help us help you. Recently I showed a fellow who couldn't find DI that a RV supplier had it the next town over … a 15 minute drive.
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True, I have to do this. Thinking of a name change too as a matter of fact.

Edit should say Sweden now.
 
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Sweden.... hmmm, don't know the DI places there.
Are there any welding supply, refrigeration places, food shippers, seafood processors, pharmacies, medical manufacturing, etc. near you?

Depending on where in Sweden, I guess you could just set them outside in the winter for deep freezing :) In Lapland it gets down to -50/-60C.
 
I would still try calling a local grocery store and see if they have anything.
 
Just checked with local grocery store fish dept (LARGE New England chain), no luck.
 
I'm way down south in Sweden, so I'm out of luck :) Usually gets to around freezing only, in the winter.
I did find one place a 15-20 min drive from here, that sells DI. But it is a 11 lb minimum..
 
Scaniaman said:
True, I have to do this. Thinking of a name change too as a matter of fact.

Edit should say Sweden now.
Click to expand...

A fellow norseman!

If I had to venture a guess based on your name, you're probably located around Stockholm/Södertälje. :D

I've bought dry ice from these guys, just bring a container, they even sell them there if you need one:

Freezit (Kallhäll)
http://freezit.se/torr-is-kolsyreis/ - I believe I pay around $20 for like 10 lbs.

Then you have the mother of all your gas needs, AGA, where I have an account and use repeatedly:

AGA (Älvsjö)
https://www.facebook.com/pages/category/Chemical-Company/AGA-Gas-AB-Butik-Älvsjö-332637140276886/

There seem to be another one in Södertälje:

Xena Entreprenad (Södertälje)
http://xenaentreprenad.se/page/kolsyreis-torris/?m=98 - according to their pricelist around $3.5 per kg (2.2 lbs)

Or...

you could also get a dewar for LN2 and fill it at AGA in Älvsjö. The price is around $50 + $3.3 per liter. My 25 liter LN2 dewar last me around 3-4 months (I have it insulated also).

Hope this helps, send me a message if you need more info.

Edit: Good thing I'm not a betting man, my guess on your location was wrong. Haha. And now I get it, Scania as in Skåne, not as in the brand. :oops:. Well, I tried.
 
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