I think this might work and solve the portable dilemma...

[spudkpi]

Okay so the picture explains most everything but what you do is open the ball valve and fill the chamber up with some water then drop in some dry ice... The ice begins to create gas and pressure and when said pressure reaches the amount you wish you simply relieve all pressure by using the modded sprinkler valve and hurtle the projectile... think it will work? I was also thinking of making it from steel?

[BC Pneumatics]

I would be amazed if a sprinkler valve survived. Even if it is brass, and the rest of the cannon is metal, the valve's seals would still freeze. Long story short, this is a poor idea. Bottled CO2 is easier, safer, and ultimatly cheaper.

Not to mention that the water would redice chamber volume, meaning you would need an even larger chamber built from (comprably expensive) metal. And.. Why have a 'portable' cannon, that is too damn cold to touch?

Also, your diagram is mislabled.

[SCrid2000]

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[DonTheLegend]

I think i saw another thread that was similar to this, but it used the dry ice to fill a separate storage tank, and then used that tank to fill the chamber on the actual gun. I like the idea though.

[noname]

If you do this, put an elbow right after the valve and before the barrel so you can hold it upright and shoot so no water comes out and you don't have to refill it.

[BC Pneumatics]

How does anyone think that this is a good idea? I mean.. seriously. It will require a cannon that would cost more than a regular pneumatic that was set up to use a CO2 bottle, not to mention that you wouldn't be able to hold the damned thing...

I'm not sure if it is ignorance or stupidity

[M3NT4L]

WHAT THE FK! bc is right are you guys must be stupid. Please dont put dry ice inside pvc pipe, pvc is brittle and the cold from the dry ICE will make it more suceptible to shattering because it reduces the elasticity of the pvc (mind the spelling, no time). To make a cannon like this you would hav to make it 100% metal that means no sprinkler valves no diaphragms. So then you would have to go with a qev (expenccive) or a ball valve (suks) and it would be cold and not portable at all. Thats only my opinion feel free to blow up

[spudkpi]

Well jesus... i didn't say one nasty thing to any of you all i simply posted an idea of mine and i quote myself asking for help:

... think it will work?

BC and mental neither one of you needed to be asses like that... my god

[MrCrowley]

ok you can try it,i dont think it will work and if it does it wont be portable it would be a waste of money and the power wouldn't be all that great.

have fun, just build a co2 cannon or a normal pneumatic
and to get the dry ice through the ball valve you would have to crush it up and you would lose most of it and then you would have to pour it in fast before it comes back out,your only using a 1" ball valve that doesnt mean a 1" piece of dry ice can fit though.

[Jarim]

good idea... ive used dry ice and watter for bottle bombs and the little bottles do good under intense pressure... so why not... i bet it would work... its worth a try at least...lol


suggestion: use warm water for a faster increase in pressure... and use really thick tubing....


the gas created is c02 so why waist money on tanks when you can just use dry ice and have a custom created gun with a new idea involved

[BC Pneumatics]

spudkpi, if I'm not an 'ass' people tend not to take me seriously, so, in short, I am an ass. Get used to it.
To answer your question, no, I dont think it will work, but only becasue I dont think you will ever pull it off without killing youself, since your post count seems to be higher than your IQ.

Jarim, those water bottle bomms sound hella cool man! got some plans? plzthnx!!

[boilingleadbath]

I'd have the CO2 generator as a seperate unit.
A preliminary cost estimate:

2"x12 steel pipe: 12$
2" endcap: 5$
2" plastic ballvalve: 13$
150 psi pop-off valve: 5$
PVC air storage chamber: 12$ (pair of 4" endcaps)
Misc brass fittings: 4$

Total: 51$

Not bad, compared to the standing bottle + regulator system.

[BC Pneumatics]

BLB, you have to factor the cost of dry ice into that too, as it costs alot more than regular CO2 would, Not to mention, the loss on this thing would be rather high.

[pyrogeek]

A seperate holding tank would be a better idea, then you could regulate the pressure better and not risk making the PVC too brittle. Otherwise, does anyone know what kind of pressures could be made using a chemical reaction like between baking soda and vinegar?

[pyromanic13]

I've already made one that runs off dry ice... but it was just some spare galvanised pipe and a ball valve, look up the steam gun if you want to see what it looks like