SpudFiles

I don't know if this is illegal on this site or anything, but has any one else tried using dry ice as a fuel for their gun. I modded one of my old pneumatics to run on dry ice and water, it saves me a lot of pumping and could get up to relatively high pressure. I would post a my dry ice cannon but I have taken it apart for parts.

what type of pressure could you get out of it

it has been discussed before
try using search to find a thread about it

i wouldn't suggest using dry ice with pvc
the cold temperature causes pvc to become brittle, and it could shatter if enough pressure built up in the chamber

sorry eddbot did not know just wondering and i am working on all metal guns because i have access to metal and the look of metal is cool

well the issue is that your "relatively high pressures" are actually incredibly high pressures. Approximately 830psi if I remember correctly, and quite cold. I would never use this without a pressure gauge, safety popoff, and some way to release the pressure other than firing the projectile if it gets too high to fire safely before you can fire it (ie: ball valve hooked up to the back of the chamber.)

jor2daje wrote:I don't know if this is illegal on this site or anything, but has any one else tried using dry ice as a fuel for their gun.

Yep they have. They aren't safe or predictable.

Its illeagal to put dry ice in an enclosed container. I dont know if a valve would count.

rp181 wrote:Its illeagal to put dry ice in an enclosed container. I don't know if a valve would count.

wait, wouldn't that mean you couldn't legally put dry ice in an ice chest?

You should have the dry ice in a spererate container not the gun, oh and i guees you might acctually reach the point whery the pressur eis so large that the carbon dioxide turns to a liquid and ud have like a co2 tank but u pay less. i would do it in a 3000psi rated pressure cylinder, everything else would be suersideal! Some one her should try liquid nitrogen, its ussally free or very cheep and its higher pressure than co2, about 5000psi i guess.

john bunsenburner wrote:Some one her should try liquid nitrogen, its ussally free or very cheep and its higher pressure than co2, about 5000psi i guess.

ummm... how do you suggest I go about getting some of this free Liquid nitrogen? As far as I can tell, given the very foundations of capitalism, they do not just give out free liquid N2

Ussally you can get ap to 10liters of liquid nitrogen directly from dealers for free or very cheeply, after all its just destilled air...

Lentamentalisk wrote: Approximately 830psi if I remember correctly, and quite cold. I would never use this without a pressure gauge, safety popoff.)

I do have a pressure gauge and pop off release valve, I used to take it up to about 70 psi before firing and it would only take a seconds to build up that pressure if I put enough dry ice and water in the chamber.

Oh ya and sorry I didn't know this was already a topic.

If you have access to lots of cheap dry ice, go for it. 800 or so psi isn't much of an issue to contain, and the hazards of very low temperatures can be counteracted by using copper or aluminum for your pressure vessel. Of course, it gets complicated, because most valve seals don't really like those kind of temperatures, and cryogenic valves ain't exactly a dime a dozen.

Overall, unless you get that dry ice REALLY cheap, it could be a better choice to use unregged CO₂ from a cylinder, although the shear ease of use of a 600 psi dry ice mortar-type gun is certainly attractive (after you get the thing built, that is )

john bunsenburner wrote:Ussally you can get ap to 10liters of liquid nitrogen directly from dealers for free or very cheeply, after all its just destilled air...

Hardly.

Yes, the raw material is free. The HUGE amount of energy needed to cool and compress the air to the temperatures needed to distill it is hardly free.

The liquid nitrogen is not a waste product of the generation of pure O₂. There is a big market for N₂ since it is used as an inert atmosphere in many industrial processes.

A compressed gas producer may well let you have a couple liters for pretty cheap but you can only store that N2 for a short period unless you have the proper equipment.

How exactly do you propose transporting a couple liters of liquid nitrogen? Last I looked a two liter dewar flask costs several hundred dollars (at least). A good dewar flask might hold the liquid N2 for a day or so. A pressure rated tank with suitable regulator will hold it indefinetely but is going to cost $$$.

a scuba tank should do it m8, the 300bar ones would hold i guess. and its well worth the cash, you know the friken power u get from that is incredible. oh and iv managed to make liquid nitrogen at hoem plus you can earn money with it by making liquid oxegen and then selling that(or using it in ur hybrid