I'm attempting to construct a butane based flamethrower using a plastic butane tank for refilling gas lighters, and a simple mechanism. What I'm trying to figure out is how to make the flame trap so the flames would not get into the nozzle and back into the tank. I've made some research and found out that the flame traps used on ships to keep the flames on board from entering the fuel tank (luckily I'm in a nautical military school, so I have teachers to explain such things) is made of a thin copper net and a metal casing with holes. The copper metal has a very high heat reception rate, so it recieves the flame's heat. So, does anyone here has any idea on how to construct one?
Thanks.

As long as there is no oxygen in the butane tank you have nothing to worry about. A flame trap is not nessessary. There is only liquid butane and gaseous butane in the tank.

I'm of the same opinion of cyclonitepyro. However, yes passing the gas through a metal mesh will stop the flame from passing through, just like in the Davey safety mining lamp. Also, bubbling the gas through a liquid like water would also work.

You could also use something like this:

<img src="http://www.hobbybrouwen.nl/apparaat/watersl.jpg" alt="" />

maybe in combination with the Cu net ...

The trouble of using water in a contraption, is making sure it stays where it's supposed to be. And if pressure is too high, it will blow the water out !!!
This effect may lessen if you use a heavier liquid, lets say Hg :D

I'm pretty sure a butane flame would melt right through a plastic fermenting airlock. :D

Brainfever, how am I supposed to use these? Please explain.
Zambosan, yes, it will, this is why I'm trying to build a flame trap :)

There is always the possibility of the heat from the flame reaching the butane tank causing it to burst...

LOL,

I'm not suggesting that the flame front moves up that close to the plastic thingy's, just build it in as a failsafe, should the Cu net burn through or melt from the intense heat.

Though it will probable not work, because of high pressure of the gas ...

The other day I was fooling around with some Right Guard Deodorant. Just shooting it through a candle. Then it burned back towards the can, after just a second of sparying, luckily I stop pushing on the top in time, and all it did was melt the hole in the cap closed. Anyways, the point is that if you are going to build a butane flame thrower like that, you deffinately need to have something to stop the flame from going back into the tank. Sounds like you need some type of high pressure regulator.

What size of butane tank are you planning on using? The ones I've seen for lighters, such as this one:

(copy and paste)
<a href="http://www.geocities.com/extremepyro2/386bomb1.jpg" target="_blank">http://www.geocities.com/extremepyro2/386bomb1.jpg</a>

don't seem to have much pressure. I only got them to shoot flame about a foot. I have seen some impressive pictures from the Burning Man Festival of a flamethrower built with a metal propane tank as the fuel source, if you wanted a decent flamethrower, that seems to be the way to go.

<small>[ May 23, 2002, 06:35 PM: Message edited by: EP ]</small>

randomquestion, the flame will not "go back inside the can". You were in no danger besides flamable liquid having dripped from the nozzle set fire to the top of the can (does happen), in which case the plastic parts *could* burn through and rapidly vent the contents of the can which would be burnt. I.e your flame thrower would go out of control. You don't need any kind of flametrap as long as your propellant doesn't contain an oxidiser and the flames from the nozzle won't over heat the fuel container.

I agree on those butane refil cans, 12-18" flame max - I made a concealed mini flame thrower before with one.

So that you should know it CAN go back inside the can if you spray it for a while (20 sec+) and yes they have blown up on people.

There is nothing but liquid coming up from the bottom of the can, up through the straw and out the nozzle, there is no oxygen at at in those cans. It is impossible for the flame to "eat" back through the liquid into a can with no oxygen and exlplode. If there was oxygen in the can and it was towards the end of the flammible liquid so that it is sputtering up liquid mixed with oxygen, then there is a risk.
But you won't find any commercial sprays with oxygen in the can.

I have definately read stories about that happening. (reliable newwpapers) The flame can travel back down the can, and apparently can explode.

I don't know how, in theory i believe it should'nt, though i suppose there is a reason behind it. Once the flame gets back to the can, i drop / throw them....

When was the last time we trusted the explosive knowledge of a newspaper? :) It *is* impossible for the flame to go back inside the can.

Yes, the one with tazer ignition.

If you feel like puking up $5 bucks, you could just use the nozzle assembly (modified for full flow of course) from a propane torch, which already have flash-back arrestors built in.

I'm with Anthony on this one, aeresol cans cant just explode, they have to heated beyond the safe pressure levels of the can, or penetrated. Usually some kid chucks one in a fire to watch it explode, and then accidently gets most of the explosion himself, then makes up some bullshit story for his mom and his doctors.

There would have to be some air in the tank before they started to pressurize it with hydrocarbon, butane, propane whatever.

The tank is about 10 cm at height, 3-4 cm in diameter, made of plastic. It costs about 5 NIS, which is about 1.25 US dollars, so it really pays off. From reading the above posts, I decided to use a double copper trap and also a water trap with appropriate sizes so it will resist the gas pressure. My question now is, should I locate the copper trap before or after the nozzle? If it is located before the nozzle it will not bother the burning gas stream, so the gas will go straight forward, however there is a disadvantage, since the spraying nozzle might expand from the immense heat and not function properly.