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Its been a while since i last posted here and this wasn't the post I would have liked to return with, but...

Can someone explain how disposable propane tanks can be used to fire a pneumatic cannon? OR, is it filled with CO2... this is all confusing, and don't bother me because I used search :hmph: I have tried to look for an explanation but this was my last resort.

Additionally what fittings/ special hoses are required?

Thanks and sorry for the noobness

The_Kangsta wrote:Its been a while since i last posted here and this wasn't the post I would have liked to return with, but...

Can someone explain how disposable propane tanks can be used to fire a pneumatic cannon? OR, is it filled with CO2... this is all confusing, and don't bother me because I used search :hmph: I have tried to look for an explanation but this was my last resort.

Additionally what fittings/ special hoses are required?

Thanks and sorry for the noobness

Disposable propane tanks have a very small valve, so to be effective, extensive modification is required. Either the valve core is removed and the bottle neck is drilled out larger, or the entire original valve is removed and something larger is welded in.

Before modifying a tank, it is highly recommended to remove the core from the relief valve and the core from the main valve and use an air compressor to fully purge the remaining propane. When it is diluted down to around 4% fuel, the mixture of propane and air becomes quite explosive. You don't want to have it reach that concentration while soldering, brazing, drilling etc. Purge the tank to 0% concentration of propane before starting any work on the tank.

If you have the ability to braze, you may find and interesting propane tank mod in my Marshmallow Cannon. The original valve was removed and a 1 inch valve was built into the tank to make a high performance launcher.

Photos, videos, and damage pictures are in this thread.
http://www.spudfiles.com/forums/quick-d ... 17858.html

The_Kangsta wrote:Its been a while since i last posted here and this wasn't the post I would have liked to return with, but...

Can someone explain how disposable propane tanks can be used to fire a pneumatic cannon? OR, is it filled with CO2... this is all confusing, and don't bother me because I used search :hmph: I have tried to look for an explanation but this was my last resort.

Additionally what fittings/ special hoses are required?

Thanks and sorry for the noobness

Simple.

1. Unscrew the mixer from the tip of the torch head. (The part the mixes propane with air)
2. Get a suitably sized piece of pressure rated hose, a barbed nipple that matches the hose and a pair of hose clamps.
3. Tap/screw the nipple into your chamber.
4. Put one end of the hose on the nipple and the other on the tip of the torch head.
5. Clamp the hose in place on both ends.

You are done.

Like tech said, the orifice on a torch head is pretty small so it'll take a while to pressurize a large chamber. (A pressure gauge would be nice but isn't required)

You can cut the orifice end off the torch head and get higher flow rates but the torch is permanently ruined if you do that. (If you don't cut anything the air mixer can be screwed back on and the torch is still useable.)

I wouldn't be a good idea to refill a propane tank with CO2. Indeed a place that refills CO2 cylinders should refuse to do it. The tank isn't rated anywhere near high enough to handle the pressure of liquefied CO2. Besides, the Bernzomatic cylinders are probably cheaper than refilling with CO2 anyway.

The pressure in a propane cylinder varies a fair amount with temperature. (See the spud Wiki page on propane). Usually a propane tank's pressure is low enough that it can be used unregulated with pressure rated PVC. On a hot day the propane cylinder will be at a higher pressure than what a typical shop compressor can do.

tech was talking about using the tank as the main chamber, while I suspect The_Kangsta was discussing the use of propane as a pressurized gas in a pneumatic. anyway, jimmy is correct, and it does work quite well.