SpudFiles

Hey what is a more powerfull for use in a combustion cannon propane or hydrogen

Hydrogen but your cannon would blow up then so use propane

Hydrogen is the most powerful of all fuels of all kinds. Never attempt to use hydrogen in PVC. Things on your body now no longer will be.

I thougt that the C2H2 burnes hotter and faster.H2-3000C/H2C2-3500C

Yes,i think C2H2(acetylene)has a hot and faster burn then hyrdogen.Prove me wrong but,just what i thought.

hydrogen and oxy has 500 psi combustion pressure.

1. Would you people ever stop giving advice without having solid info on the issue?
Par example... where the HELL did sgort get the idea that H2 is the most powerful fuel ever? Seventh grade chemistry tells us the oxyacetylene torch can yield 3480 °C, while oxyhydrogen only 2200 °C. Practical experiments on Brainiac also show acetylene to clearly be a better explosive.
And as I've said a few times before, I've seen a dozen "carbide cannons" made from drain PVC that held up the pressure, but eventually got contorted because of the heat.
2. What the hell does combustion pressure have to do with anything? It refferes to the pressure at which the gas spontaneously detonates, so unless you plan on containing H2 at 500 PSI inside a tank without porous material inside you're pretty safe. Containing H2 is an issue of its own.

So in a nutshell, H2 is probably more powerful. But you'll have to generate it on the go, since it's difficult to contain.
Propane is pretty inexpensive and easily available. I use butane because it's even more available.

if you are all curious check out the upper and lower explosive limits here. it will give you all of the percentage or the air/chemical mixtures needed to have a successful reaction. also, never EVER use acetylene, using acetylene will make for one quick trip to the hospital or the local authorities.
http://www.engineeringtoolbox.com/explo ... d_423.html
copy that link into your browser, you will see a long list in brackets, but it will be in a very small font, copy and past that into microsoft word, and resize it. it will give you the percentages for every flammable gas known to man.

I suppose I was probably wrong. My logic was "If anything was more powerful than H2 then why are H-Bombs still the most destructive force known to man?".

I'm thinking maybe that with a set chamber volume H2 may be more explosive because there is a higher ammount of molecules able to react in H2 and O2 than C2H2 and O2.

Think about it. 2 parts of H2 and 1 O2 will take up 66.6% of the chamber volume for H2 and 33.3% for O2. 2 parts C2H2 and 1 part O2 will be somewhere in the neighborhood of 80% C2H2 and 20% O2 because that carbon takes up 40% of the space. (ish)

Molecule for molecule I think C2H2 is more powerful but Volume for volume it would seem Hydrogen is more powerful. Still, I could be completely wrong.

The H2 molecule is stable>energy is needed to brake it so the H atoms will react with the O atoms.The C2H2 is much more unstabe(Cu2C2 was supposed to be an explosive)> it burns faster and with a little more heat.I think we shuld stop looking for all these exotic fuels and just add O2 to the already riched mix when we need more power.

If anything was more powerful than H2 than why H-Bombs still the most destructive force known to man?

That's the funniest thing I've heard since Robin Williams on Broadway.
If you could make an H-bomb with hydrogen and matches, do you think Al-Quaeda would have settled for a couple of buildings?
H-bombs are based on NUCLEAR FUSION, the same thing that makes stars shine. Two Hydrogen atoms are squished together at immense pressure and heat to merge into one Helium atom, radiating a lot of energy in the process. You'd still need a fission bomb to generate the above-mentioned immense heat and pressure.
I tell ya, the mind works in misterious ways...

@Flinchy: Thanks for the info. Interesting chart, indeed. What we can draw from it:
H2 is actually a better fuel for spud guns because you don't need precise metering: it will ignite anywhere between 4% and 75% mix.
Butane is slightly more sensitive than propane, but will also last you a little longer.
Looks like alkohol is also pretty insensitive, but since it's a lot less volatile than the previously-mentioned, you'd have to spray it to a fine mist.
Pyrophorous gasses like Silane are the least capricious, while acetylene, with it's high energy output and wide ignition window, remains in 1st place.

sgort, clearly the concept of gasses has never been explained to you.
Here goes: they are mostly empty space, and bigger molecules therefor don't matter much.

1 mol of any gas takes up almost exactly the same volume as 1 mol of another gas; 22.4 liters at STP.

This means that if you used a 2 C2H2 / 5 O2 mixture (which is correct; 2:1 isn't) it'd be 2:5 (~28% and ~72%) by volume too.

Wow, I slipped up like 3 times there. Sorry. Yeah I forgot to compensate for the Carbon in the C2H2. 2:5 would be right, yeah, my bad. And the volume thing, yeah, I wasn't sure if C2H2 would apply to that. I had thought it was only Noble gasses by themselves or something... I dunno.

As for the H-Bomb thing, I forgot everything I had ever know about em I guess. <skooled>Gort</skooled>

In a joking manner, I'd point out that if there was indeed a 'schooled' tag, it'd almost certainly not require a closing tag - in the manner of the img tag, for instance.

...so, <schooled> or something like that.

Oh you know I think it would be like this really: [skooled="sgort87"] Yeah, I like that one.

(<> should really be there instead of [ ] but it wont let me because it removes most of what's there somehow.)

I'm thinking that was what you were goin for BLB. Yours is exactly what mine looked like after I used <> even with my name in it and such.