SpudFiles

Is it possible to fill a chamber with CO2 produced from dry ice and water? As in, the dry ice and water are mixed in the chamber itself, producing pressure enough to blast a burst disk?



Is it possible to harness the pressure produced by the reaction into a chamber?

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It's possible, though dangerous. If you do that, you're going to significantly lower the temperature of the pvc and make it very prone to shattering from the pressure. If you used metal pipe you'd be good, btu I'd say use a burst disk so you can control the amount of presure. Also, it would take a bit of time to build up the pressure in the chamber.

Plausible, but not practical.

Ah yes. The smell of blood and pvc shards in the morning, you have to love it. The main problem with this is too much energy being released at once. I suppose if you had the perfect amount, you could get a decent shot off without losing your head, but you would probably get too much or too little dry ice. To me, i feel it's too ineffective to use, and not worth it. Lets just say I wouldn't be around when you tried it.

Dry ice bomb powered cannons have come up before.

I wouldn't do it because it's as bad as pumping up a cannon with a pump until the burst disk blows which is unreliable and tends to be a bit nerve wrecking. Especially if the disk doesn't blow as planned.

What flamerz describe will certainly work. It would only be safe with a burst disk gun (like he suggested). It would also be a good idea to include a pop-off valve rated to say 100 PSI.

Even though it'll work it does have some serious problems. Like Paaiyan said, you'll freeze the PVC which is not good. Another problem is that you really have know idea when the the gun is going to fire. And, once charged it pretty much has to fire (unless you include a pop-off valve).

Maybe it is just me, but the idea of a gun that goes off when it wants to instead of when I want it to is kind of scary.

Mabye use a small chamber constructed of heavy metal and use that to mix dry ice and water. With a valve, perhaps a gate valve, allow for some gas to pressureize the main chamber and then with a piston valve empty it and shoot whatever projectile you are using. Also the smaller chamber could be attached to the main chamber through a lot of smaller diameter hose coiled around the main chamber and then plumbed into it. That way you are positive that only gas is going into the chamber and no cold liquid.

What flamerz describe will certainly work. It would only be safe as a burst disk gun like he suggested. It would also be a good idea to include a pop-off valve rated to say 100 PSI.

Even though it'll work it does have some serious problems. Like Paaiyan said, you'll freeze the PVC which is not good.

Another problem is that you really have know idea when the gun is going to fire. And, once charged it pretty much has to fire (unless you include a pop-off valve).

Maybe it is just me, but the idea of a gun that goes off when it wants to instead of when I want it to is kind of scary.

Another random thought to add to this thread, but has anyone tried using an alka seltzer tablet and water? That combo would also generate pressure but no extreme cold.

I think that video you posted is reason enough not to try, those individuals are prime nominees for future Darwin Awards

But paintball guns use liquid C02 and they dont blow up. I think that if constructed well and used by an individual of some intelligance it should work well.

Paintball guns are constructed of nothing weaker than high-grade aliminum, the CO2 tanks are steel. You're talking about PVC most likely, not a good candidate for a high-pressure, low-temperature situation. Also, the liquid CO2 is not very cold at all. It's only a liquid because of the pressure, whereas dry ice is solid because of the temperature. There's a big difference. Not only is the dry ice cold to begine with, btu the sublimation of CO2 will make it even colder in the chamber. There's also the little problem of the dry ice freezing the water in the chamber and you having to clean it out every time.

If you're going to build a cannon out of pressure-rated steel and proper fittings, hey, go for it. it'll still be a pain in the butt to work, but have at it. If you're planning on building one out of PVC, can I please have your name so whenever I see it in the next issue of the Darwin Awards, I can say I told you so.

I do what I want!

If I had a nickel for every time this was asked on the SGTC forums, I'd have some serious money. Simply put, it's impractical to the point of uselessness. And, considering how much dry ice is per pound, you'd be far better off by just renting a CO2 cylinder. It's usually only about 20-30 bucks. Navigator7 can give you more details.

How much is it to rent a canistor? And also has anyone used Nitrogen?

Yes, many a person has used N2 as a portable pressure source. Searching in the Bible (SGTC archives), Nav7 said it's 5 bucks a month for the rental and 20 bucks a fill. Not bad.