help with flamethrower design

[JDP12]

Hey all, here is my design, please excuse the bad drawings, I was really tired when I did it..The reason for the nipple after the valve is so taht it doesn't melt the plastic on the valve.

My main things I need help on are:type of fuel, but any tips or suggestions would be greatly appreciated thanks

<img src="http://i157.photobucket.com/albums/t79/ ... 1179193363">

[cb4289]

Homemade Flame Thrower
Mirrored from the Something Awful Forums

Posted by: RolandTower
Posted on: Jun 27, 2004
Like any red-blooded, masculine man of the male gender, I love PVC weaponry. You should too. If the concept of heading on down to the local Home Depot and transforming $100 worth of random pipe bits into a killing machine doesn't appeal to you, you're a goddamn pansy. Also, you're probably sane and will live significantly longer than I will. Nonetheless you disgust me, and I take comfort in the knowledge that your obituary will be nowhere near as humorous as mine. For those of you who laugh in the face of hypersonic shards of plastic puncturing your spleen, here's an intimate look at how I've kept myself busy for the past week: building a PVC flamethrower. If you're not interested in the building process, skip to the bottom of the post for the fire. My flamethrower has two main parts, a gun/hose assembly, and the tank. I made the gun first: It's made entirely of parts you can get at your average hardware store. The hose connects to a stop valve, which connects to a short pipe nipple that's tapped directly into the tank. The tank took a while to make, because I let each set of chemical welds dry before doing the next ones. The ends of the tank are two 90° elbows and two 90° street elbows, welded to make two full 180° "U"s. One side of the tank is a 2' length of 4" sch.40 PVC, the other is a 4"x4"x1.5" T with standard pipe attached to each 4" socket. Before assembling the parts, I drilled and threaded the two holes I needed in the tank ends: a 1/4" standard pipe hole for the outlet to the hose, and a 1/8" standard pipe hole for the valve that I would use to pressurize the tank. Interesting note: 1/4" and 1/8" pipes have no actual relation to the measurements of distance commonly known as the quarter inch and eighth inch. The holes are actually 7/16" and 11/32" respectively. Hooray for non-metric measurements. Next step: cement one end of the tank: Then the other: After the tank dried, I dredged up an old camping backpack to hold it. I cut a hole in the bottom of the pack and screwed the gun/hose assembly into the base of the tank. Finally, I screwed in the Schrader valve (tire valve) to complete the tank: Now the whole rig was ready for some pressure testing. Since I would soon be running the distinct risk of giving myself heat-assisted, deep tissue exfoliation, I was extra-careful to make sure there weren't any leaks. I used up a lot of Teflon tape. And, after filling the tank with water for a trial run, made sure the cleanout cap was on nice and tight before flipping on the air compressor. No leaks! At this point, I had quite possibly the world's most kick-ass super-soaker. Of course, I didn't go through all that effort for a damn squirt gun. So I added a pilot light in the form of a blow torch. Much better! The finished product

[cb4289]

that was a thing i got off the net though i wouldn't suggest using a pvc tank I would use a tank from northerntool.com use the 10 gal tank it has a shrader valve in it already. Use some gas pipes as the handle try to put in a few metal one way valves in and use alchol lacquer or gas as the fuel but not propane trust me!!! Also use brenzo o matic for the ignitor .

[cb4289]

here is a pick of the tank

[cb4289]

here is another picture

[Killjoy]

Thats the guy who inspired me to build my flamethrower. His desighn though consist of more dwv parts then i would be comfortable using so be warned.

Ilove,
That design looks good, but don't bother with the sprinkler valve, and make sure all parts are pressure rated. Also, for the ignitor you can just use some copper tubing (1/4") and bend it to form the nozzle, and connect this to your propane bottle to the tubing with epoxy or what ever

For fuel you can use denatured alcohol, but that can be expesnive but it doesn't have any effect on the pvc, you can also use gasoline, but its effects on pvc are still not entirely clear.

Edit: Heres the link to the one i made which is slightly similar to yours http://www.spudfiles.com/forums/killjoy ... t7082.html

[cb4289]

if you live in the hills just use moonshine or if your a city slicker use everclear i think everclear will work.

[subterranean]

im not quiet sure why you have a sprinlker lalve on there, but good disign o far. insted of having a T fitting leading from your propane tank, you cluod usea 4 way , and use the extra opening to run a line to your gun, to use as and igtitor. i believe you can but a propane vlave and nozzle with an extension hose at lowes, this would work well as a pilot flame.

[cb4289]

if you use pvc make burst holes using psi rated silicone it'll save your sorry life it works by sealing up holes up with high psi silicone but the kind that that is still flammable look for it on the web then go over it with a really thin coating of super glue oh and ps read

Ragnar's Action Encyclopedia: A Do-It-Yourself Guide to Choosing the Right Weapon, Assembling a Sniper Rifle, Making Improved C-4, Taking Out Tanks and Apcs, Acquiring New Id,: Ragnar Benson
Paperback, 1997 - Buy it for $27.44 (Save 31%)

Breath of the Dragon: Homebuilt Flamethrowers: Ragnar Benson
Paperback, 1990 - Buy it for $23.49

you can get them from www.half.com they have 4 the highest price is 80.00 the lowest is 24.00 s&h is allays 4.00

[JDP12]

cb4289- what do you mean by burst holes??? It seems you mean that i should make a hole, fill it with epoxy for the purpose of the same thing as a popoff valve...why not just use one of those???

K I am updating this...drawing will be coming soon..I just can't find the original- think its on my home computer and i don't want to draw up a whole nother one soo this is what I'm changing..Tell me what you think

1) Ball valve instead of sprinkler valve

2) smaller diameter nipple after valve ( this gives the stream some sense of direction) then after the nipple a hose barb ( thanks killjoy for the idea like on yours

3) 3" female adaptors on top, with cleanout caps so I can fill it with liquid..Kinda forgot about that

4) Instead of having all those adaptors to get to a small hose size..I'm just going to use some end caps and drill through those and put a nipple through there- it saves a lot of money..DOn't have to buy a bunch of parts to reduce it..

Couple questions still though

1) Do you think I should have a separate propane tank for the ignitor, or should I run a line from the pressure propane tank??

2) So the best fuel is pretty much denatured alchohol??
EDIT: here is the new diagram..I don't even think I would need a regulator between the propane tank and chamber..I was thinkin of just using a ball valve, and shutting it when I want to fire so the propane tank can't blow up..But like I said before.. I need help on deciding whether or not to have two separate propane tanks- what would be more efficient??

Here's the link, you may have to copy and paste it into your browser. http://img2.freeimagehosting.net/uploads/d07165bfda.jpg

Thanks guys,

[cb4289]

burst holes using psi rated silicone works by sealing up holes up with high psi silicone but the kind that that is still flammable look for it on the web then go over it with a really thin coating of super glue


oh by theway thiis mightmake me sound dumb but what is a popoff valve
ithink i know what it is i probly just call it sopthing diffrent.

i'm aslo looking fword to your posts a i'm going to build a 30-50 gaallon flame thrower

[JDP12]

Umm I still don't get it..

A pop off valve is a valve that you install in your chamber, and it pops open if it reaches too high of a pressure- so it doesn't overpresurize and blow up on you

So what do you think about the pilot flame part?? Use a separate propane tank or use the same one??

[cb4289]

[quote]A pop off valve is a valve that you install in your chamber, and it pops open if it reaches too high of a pressure- so it doesn't over presurize and blow up on you ; ilovetoblowthingsup

if the fire goes back into the tank for a second if you pressurize it it can explode, at least that's what i'm told so when the fire goes back into the tank the silicone should melt in the intense heat allowing the fire to escape and the tank wont blow and create shratnal be it metal -nasty stuff - or plastic still nasty. so good luck building this thing.

[JDP12]

Yea we'll see what happens..If it even gets off the ground..lol..I'm currently tied up in a bunch of stuff- end of year finals(ugh), having fun with my combustion(not really a project lol) and designing/building a cool little(actually its not little it's gonna be big) piston gun to shoot T-Shirts among other things.. so we'll see what happens.

[zeigs spud]

im not quiet sure why you have a sprinlker lalve on there, but good disign o far. insted of having a T fitting leading from your propane tank, you cluod usea 4 way , and use the extra opening to run a line to your gun, to use as and igtitor. i believe you can but a propane vlave and nozzle with an extension hose at lowes, this would work well as a pilot flame.

yea sprink valve can acualy be quite BAD>
it can let out excess fuel wich can get on you and ignight
and it can is just a storage area for air and more chance of a black flash fire.

simpley don't use it. plus some fuels can carode (i think that is the right word) the diaphram of most sprinks.

i don't know if any one has posted it yet but NEVER us gasoline as a fuel, it is carosive to pvc and is TOO flamable, to put it simpley....if the fuel fumes ALOT and it's fumes are easly lit, don't use it as a fuel. also make sure it wont eat away at ur pvc.

here is a small min replayin vid of that first non main topic thrower---

A pop off valve is a valve that you install in your chamber, and it pops open if it reaches too high of a pressure- so it doesn't over presurize and blow up on you ; ilovetoblowthingsup

if the fire goes back into the tank for a second if you pressurize it it can explode, at least that's what i'm told so when the fire goes back into the tank the silicone should melt in the intense heat allowing the fire to escape and the tank wont blow and create shratnal be it metal -nasty stuff - or plastic still nasty. so good luck building this thing.

ROFL!!!! i sugest you get more experince wih throwers or acualy reseach them a lil more before you give advise such as that....not dissin..just saying lol in my past flame thrower topic we discussed the "back flash fire" in throwers.

1-this "back flash fire" only happens 2 ways, 1)if there is a flaw within the tank and fuel can escape or 2) there is flaw within the delivery system of fuel, primarly the size of the hose delivering the fuel and the hole it exits

*like in some real flame throwers or peizo lighter the exit hoel of fuel is too small to provide sufficient enought air to fuel ratios to ignight, also as the tank is pressurized the fuel exits allowing no air in,if i remember right the hole can be about 3mm-4mm in length and be safe. going to to cm is pushin it though and the pilot lightshould e farther from the exit hole.

2- a pop off vlave will NOT do anyhting to protect you, infactit is jsut more chance of flaws in the chamber. if you pressurize ur fuel with normal air, which most home made throwers are pressurized with, there is oxygen, pressurized fuel and oxygen on your back is another name for a bomb on your back, it wont melt the pvc, it will blow it to peices along with you.
back to the pop off valve, when you pressurize your fuel and you have air in there thats going to explode, the pvc wont be abe to hodl that pressure nor will the valve, they will both go KABOOM!!!! even if the pvc codl hole it for 5 seconds thats probably not enough time for all that pressure to get out such a small hole.

FOR UR SAFTEY lol