SpudFiles

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I agree with Bubba05, But TurboSuper does pass a good point, PVC dust is actually hazardous.

yeah just like any plastic thats but turned to dust! wel i wouldnt wanna breath it in!

Bubba

I would trust a RATED piece of ABS, but i'm not sure i would trust it more than rated PVC.

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Yeah every one knows (mostly first hand) what PVC dose when it fails.
Boys every time this comes up it ends the same way. some like ABS some like PVC both material have there ups and downs. Put it this way they both make sick cannons!
What ever you prefur is your prefrance.
I just want to here the end of the ABS vrs PVC argument that goses on and on and on and on and on and on! well you get the point!
I've never made a cannon outa ABS as we dont get good size ABS here. I think i mentioned it's only used for reticulation. But now im getting real keen to make a mini and see just how good/bad the stuff is.
I'll let you guys know how i get along. If the bastard thing expodes and i get hurt.........please REMEMBER ME!!!!!!!!

Bubba

I can't find pressure rated ABS anywhere near me, only PVC, otherwise I would give ABS a chance.

Exactly the situation in my area

Just thinking about the steel thing again (yes, I did read what you said BCP):

IIRC, corrosion is dependant on the presence of both oxygen and moisture at the same instant, which doesn't really happen during the combustion process. There should in theory be no region where both oxygen and water are available in sufficent quantity to do major damage.

And what about the use of a sacrifical node? A lump of zinc or Magnesium could be attached to the system in the right fashion to reduce any Iron ions (i.e. any oxides) present back to their elemental form, reversing any minor damage done by oxidisation. (And all damage should be relatively minor.)
The process works fine for steel hulled boats, so what about here? Or am I missing something big?

joannaardway wrote: IIRC, corrosion is dependant on the presence of both oxygen and moisture at the same instant, which doesn't really happen during the combustion process. There should in theory be no region where both oxygen and water are available in sufficent quantity to do major damage.

CO2 and H2O can form carbonic acid, the electrolytic properties of which would further promote rust from the O2 produced as a reaction byproduct.

Te sacrificial node might be worth checking out, provided it would work on a microscopic level (?).

I may be concerned with pure Mg during a high ROF situation.

Electrolysis is a big factor when using steel, especially if using opposite metals without a dielectric union or something, but the only place that you would notice to be rusty at first are the threads, because there is no zinc coating on them, (if using galvanized steel). If you used black iron pipe, that is just plain wrong because it is rated only for gas lines, and the elements would get to it so fast it would shoot rust out.

BC Pneumatics wrote:The sacrificial node might be worth checking out, provided it would work on a microscopic level (?).

I may be concerned with pure Mg during a high ROF situation.

The node could be outside the chamber and still work fine, so need not be exposed to the actual combustion.

The nodes work down to the molecular level, over time (not instantly mind) then any damage to the steel should be reversed quickly.

ive been building DWV ABS cannons for years. never had a problem. im as low tech as you get. i brace the gun on my thigh and light it with a bic. have the scars to prove it. but ive never had the materials fail on me. had my first one for probably four years. dont anymore cause it was at a friends and we had a falling out. its easier just to build another. but yea id never use pvc. ive never liked working with it for even sprinkler systems.

and spudblaster, you only lost some arm hair? haha ive lost eyebrows, half my head burnt, etc. burn off your eyebrows then have em not grow back in properly. then you can bitch.

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Think starting fluid would be too powerful? I'm almost done with a huge cannon (DWV ABS) and that's what I was planning to use as fuel. I'll add a 1/16" hole in the beginning of the barrel if starting fluid is too strong a fuel.