Modify CO2 extinguisher to chill steel ?

[lalatheman]

According to this website

http://www.shaverkudell.ca/

liquid CO2 is minus 192 degrees F
I have a few old CO2 extinguishers full laying around , however my understanding is that a syphon feed tank is needed to get liquid out and they are not that.
Since the mechanism easily unscrews from the thank with a large standard pipe thread, I'm considering taking an empty apart and putting a bottom feed pipe in , then refilling it from another tank or if this refilling isn't practical, it could be commercially filled.
I am aware the local welding supply sells liquid nitrogen at $7 a litre into the buyer's styrophone container and its somthing like minus 340 degrees F.

However

I got a pickup truck load of old CO2's and would like to have deep chilling capabilitys always available.

Anyone have any experience or thoughts on the practicality of this ?

David

[danlb]

just make sure that they are correctly marked to prevent anyone thinking that they are fire extinguishers.

Don't you get the liquid when you tip it upside down? I do that with compressed air cans.

Dan

[Optics Curmudgeon]

Liquid Co2 does not exist at ordinary pressure, if you siphon it out of a cylinder it turns to dry ice instantly.

[lalatheman]

Thanks for the warning about marking a modified tank.
That website just said syphonfeed jug for liquid extraction.
Proclaming Liquid CO2 is minus 190 F is OK . . . .but where and when ? In the bottom my tank today its 70 degrees. Seems to me it at some point in the bell shaped nozzel it changes from liquid to vapor and cools its self as it expands ?
Now I remember years ago using an extinguisher to make dry Ice by blowing it into a tied off leg of old pair of pants. That was horribly inefficient although it did make a bit of dry ice
But dry ice is not liquid and I have heard (I think ) that dry ice is more like minus 70 or 90 or so.

David

[radkins]

FWIW, I have for the last 30 years or so used CO2 to freeze bearing and bushings and it's very easy to do. What we always did was just attach a hose to a CO2 MIG welding tank (Don't see why a fire extinguisher wouldn't work) then invert the tank and place the end of the hose inside a box or cooler filled with towels or shop rags. When the tank valve is opened the liquid CO2 will discharge and instantly form dry ice, if the part is small enough to place inside the box or cooler being used it will usually become encased in dry ice.

[Lew Hartswick]

Just query "Phase diagram" for various materials like CO2 and you'l
see that if it's under enough pressure to make it liquid it can be almost
any temperature, like "room temperature" for instance. Just see
what the range of temperatures are possible at atmospheric pressure
and it will be obvious.
...Lew...