Liquid Nitrogen... for freezing... anyone have any thoughts?

[SPYDERLK]

I have not, but dry ice isn't made that way. I can't see any way that I could have it frozen in and around the foam, given the way dry ice is produced. But it might be cold enough to solidify the foam long enough to test. Which is all I am after at this point.

What do you see that would prevent the foam being in the cold co2 liquid and getting the "snow" incorporated through and through in the cells as it got colder?

Dry ice - Wikipedia

 

[IslandTractor]

What do you see that would prevent the foam being in the cold co2 liquid and getting the "snow" incorporated through and through in the cells as it got colder?

Dry ice - Wikipedia

I don't think dry ice has a liquid form commercially. Pellets yes but I have never heard of liquid at normal atmospheric pressure.

 

[ustmd]

I have had a lot of experience with gas cylinders. I ran service centers and calibration labs for Mass Flow Controllers and we used 10 different types of high purity (6-9s) gases for calibration.

Dewars are rated by the amount of liquid Gas (in this case N2) they hold. Typical sizes are 180 liters and 230 liters (~3 ft diameter, 5 ft tall) and are on wheels. Most of the time you can't buy the dewars, you have to lease them on a month to month basis. The rental is where the gas companies make their money. I would pay $50-60 for 230 liters of N2 and the lease for the dewar for the month would be $90.

I think you will have trouble finding a 5 gallon (20 liter) dewar. The smallest dewar I ever saw was a 120 liters--~30 gallons.

In the old days we would pull liquid N2 off of the dewars for the N2 traps for the Helium leak detectors. It is not difficult so long as you have the correct PPE.

The only other concern I would have about using N2 to freeze the foam is that the foam may shrink significantly.

Good luck

 

[buickanddeere]

Dry ice mixed with alcohol gets awful cold . Cold enough to stiffen the foam for certain.

 

[buickanddeere]

A medical supply house may have smaller 3 to 5 gallon units ?

 

[CalG]

dry ice purchased from a beverage supply has a lot of H2O included in the weight. It's cold though ;-)

 

[oldpilgrim]

I'd bet the foam would become shatteringly brittle in LN.

 

[Weedy Fields]

at a certain point I think that making a mold is will be quicker. If you have to do a couple of processes and have time limitations for maching the foam then where is the advantage over the mold. I can't imagine injecting the foam into the mold is a time consuming or difficult process.

Sometimes its more efficient to have more easy steps than fewer more difficult steps in processing a product.

Would machinable wax be ok for a one shot mold? could machine it very quickly.
Melt the mold down with the chips from machining and your ready for the next mold.

 

[SpringHollow]

Freeze the foam in water to form a block of ice and mill that? Being open cell foam, that should work I would think.

Ken

 

[/pine]

...liquid Gas...

I hate it when that happens...!