In case no one told you, flamethrowers are really dangerous. This is NOT an instructable for kids! This is for educational purposes and if you attempt this you are doing so at your own risk. I am not responsible if you get hurt attempting this. The responsibility for your safety depends on you! I try to discuss how to do this safely throughout the instructable so, READ EVERYTHING CAREFULLY, but realize I can't think of every safety problem. HAVE A FIRE EXTINGUISHER HANDY! If you do not have a high level of understanding of the chemistry and physics involved you really should not do this.
That said, science and learning without danger would yield no cars, no fireworks, and no disease cures. So, I'm going to donate my body to some dangerous science!
Maybe some of you experienced a common flame test lab in high school. The one where you try to identify the presence of different metals by dipping little sticks in alcohol mixed with salts and observing what color the solution burns. This is basically like that on super soldier serum. This little baby can shoot up to 5 feet of flame and shoot two colors at once (three colors are possible if blending the fire streams). This thing can produce impressive flames for up to twenty seconds. To me, that's pretty sweet for a pocket-sized flamethrower holding maybe 20 grams of fuel.
BUT CAN'T THE FLAME GET SUCKED INTO THE CANISTER AND BLOW UP?!
No. In this case the fuel canister is made safe with self pressurizing butane fuel. In order to have fire you need fuel and an oxidizing agent such as O2 (makes up ~20% of air) or N2O(nitrous oxide) or one of many other oxidizing agents (oxygen may not even be involved). Since the canister is full of fuel with no oxidizer, it is not going to explode. If this were not the case, bic and other butane lighters would all be potential grenades in your hands. Their fuel sprays directly from where it is stored, into the flame. Some may say, but I've seen videos of lighters turned into little explosives. True and this could blast fire everywhere too if the plastic canisters melt and release the fuel. The container can explode if there is a second hole in the container, as this could cause air to get sucked up into it. You still have to be careful here.
To achieve colored fires another fuel, 100% denatured alcohol, is added to various fire coloring ionic compounds and mixed in with the butane. Some of these ionic compounds are toxic (very small amounts are used though), as is denatured alcohol. Yet another reason to be cautious.
Why do the chemicals used produce color? As the metals in the ionic compounds get hot, their electrons get bumped up to a more excited orbital state. It is an electron's nature to not want to stay in this excited state. So, to go back to the way it was, it rids itself of energy in the form of light. Due to different metals having electrons in different orbital states, the different metal's electrons emit different colors of light when excited. Since the alcohol and butane don't really emit much visible light, when burned efficiently, (like with the high pressure nozzle used here that mixes in a lot of oxygen with the fuel ) you see the colors emitted by the metals clearly.
How does it fire? I just simply push the little clear plastic tabs down onto the butane tanks' valves and out comes the pressurized fuel over a flaming pilot light wick. Each tab activates one tank making multiple colored blasts possible.
Make sure to read all the picture notes too.
You can't be a convincing pyromancer/pyrokinetic without fire! Turn an ordinary walking stick into a WIZARD STICK OF DOOM!!!
Step 1: Rounding Up the Tools and Parts
Nitrile gloves (preferably thicker/better chemical resistance than I used) -Drug store-
Denatured Alcohol -hardware store/department store-
Pure SrCl2 hexahydrate salt -eBay/chemical suppliers/United Nuclear-
Boric Acid -Hot Shot Roach killer (check the ingredients) -hardware store-
Copper(I) Acetate and/or Copper(II) Acetate -eBay/ chemical suppliers/United Nuclear-
Potassium Chloride (No Salt Salt- or get the pure stuff) -grocery store/ebay-
Sodium Chloride (regular table salt)
Bernzomatic mini butane refill canisters (There are other similar products out there, but their dimensions may be different and I don't know how well they will work for this) -hardware store or Home Depot found with in area w/ barbeque lighters-
Leather strips or a leather belt to cut up (fuel tank strap)
Adhesive hook and loop velcro strips -hardware/walmart-
Tiny bic lighter (optional)
All metal lipstick tube (small retractable metal makeup brush w/ cap could work too) -eBay/department store/metal lipstick pipe on amazon may work as well-
4 tiny machine screws with nuts (many workable sizes)
4 slightly larger machine screws with nuts (also many workable sizes)
1 small machine screw with locking nut (pick a small size)
Aluminum sheet .064" thick -Ace Hardware/eBay-
Aluminum sheet .032" (optional) -Ace Hardware/eBay-
Rectangular brass tube (optional) -Ace Hardware-
Flat fiberglass wick/fire stove component -Ace Hardware-
-2.3 mm - 2mm inner diameter (Must be this diameter for safety) nitro line silicone tubing (I used DU-BRO 2239) -RC hobby shop/Amazon/eBay-
2 small flat washers(many workable sizes, but must be able to push down butane tank nozzle) -hardware store-
Large butane refill canister with standard refill nozzle -hardware store/walmart-
Cups, HDPE plastic containers, or glassware to mix up and measure colorant solutions
Stir rods or sticks
3/4" x 5/8" brass hinges -Ace-
Lexan polycarbonate sheet .1" aka 2.5mm thick (plexiglass is too weak and will break) -Home Depot-
Brass rectangular tube 8mm x 4mm -Ace hardware- (optional)
Thread -Walmart/Michael's- (optional)
3/32" x .014" round brass tube -Ace Hardware-
9" long reusable zip tieabout 1/4" wide -Walmart-
High temperature silicone muffler paint -auto stores-(optional)
Big ole walking stick (preferably enchanted) -Local walking stick emporium-
Not everything is pictured.
Rotary tool with fiber reinforced metal cutting wheel (use safety glasses while operating especially with cutting disks)
Band saw (optional)
Metal cutting hack saw (optional)
Needle nose pliers (preferably wide and flat)
Clothing that does not contain: polyester, nylon, spandex, or any other material that could melt to your skin if caught on fire
Large damp cotton towel (for fire safety)
Bucket of water
Syringe w/ no needle (hardware store/local crack dealer)
Metal vice (optional, but highly suggested)
Leather sewing needle (Walmart/Michael's)
Step 2: Cut and Shape Fuel Tank Holder
Cut up the aluminum sheet to the dimensions shown. You can bend the little tabs that hold the fuel tanks in place with a pair of pliers or by putting the aluminum sheet in a vice and bending them. Bend them nice and strait and only once, as it will weaken the metal considerably if you keep bending it back and forth. Make sure to use aluminum that is around .064" thick or else it will bend too easily.
Step 3: Attaching Hinges for Fuel Canister Nozzle Levers
Drill holes to hold your hinges (use something to secure the metal don't just hold it). Mount exactly as seen in the pictures. Mount hinges with nuts and screws. Make sure the screws aren't sticking out so much that the fuel tanks can't sit flush with the metal backing. I used a rotary tool to cut off the part of the bolt that was sticking out. Use locking nuts for this entire build or some kind of epoxy to fasten the screws securely when you finish everything.
Step 4: Making the Polycarbonate Canister Nozzle Levers
Cut the polycarbonate to the specified sizes. Make sure the holes for the hose and nozzle are big enough that the hose can fit through and sit well when the lever is pushed down on the nozzle. The nozzle holes must be big enough to fit the hose, but small enough that the washer does not go through them. You'll need to add a notch at the nozzle holes as seen in the pictures to allow this polycarbonate lever to slip onto the tanks.
Secure the polycarbonate in a vice or use some kind of tool to hold it while drilling it because the drill bit is likely to catch and spin it out of your hand. I cut myself and ruined a hinge because I did not do this. Sad thing is I totally knew better... Remove any sharp edges from the polycarbonate so that neither you nor the hose gets cut. Bolt the polycarbonate to the hinge and make sure to countersink the hole for the screw so that the lever can fully press down the tank valve. Cut any of the bolt that is left sticking out past the nut with a rotary tool. I would recommend bolting the polycarbonate to the hinges first to figure out where to drill the nozzle holes. You may want to then unbolt the polycarbonate rectangles to clamp them down and drill all of the holes.
Step 5: Flame Guard Construction
Cut and bend this guard as specified. I used thinner .032" aluminum sheet here. Bend the remaining metal on the tank holder and cut off any extra so you achieve what is in the picture. Attach the flame guard to the rest of the tank holder with a small bolt. Put some epoxy on around the screw when done with the project, just to make sure none of the pilot light's liquid fuel leaks out here. Keep an eye out for that! You may wish to use even more metal than I did to cover even more of the fuel tanks. The clear plastic does not melt with butter like ease, which helps. The yellow plastic does not seem like it would hold up as well though. Regardless, watch for where there is heat on the tanks.
Step 6: Pilot Light Construction
Empty the all metal body lipstick tube of all its lipstick paper and plastic. Cut the lipstick tube as specified. Run the bolt from the flame guard and tank holder through the middle of the lipstick tube and fasten it on with a locking nut. Cut a fiberglass wick/rope to the size shown. I used a flat wick/rope from the wood stove section of ace hardware and just doubled it over on itself a couple of times. Stuff this wick into the lipstick tube. I actually gave the inner lipstick tube a coat of high temperature silicone muffler paint too. It's not necessary, but will protect against corrosion from the coloring salts.
Step 7: Make the High Pressure Firing Nozzles
The flexible tubing used here is very important. Don't use vinyl tubing for this. Vinyl tubing gets rigid and leaks at the nozzles when the super cold butane comes out of the canisters. Rapidly expanding gases cause cooling (the tubes will feel as cold as ice when operating this device). It's the same principal that makes a refrigerator work. Nitro line is made from silicone and is somewhat fire resistant and does not get rigid in the cold. Check and be absolutely sure that the nitro line you use stays on the butane tank nozzle. If the diameter of your hose is too big it will just get blown off or slip off. The stuff I used is said to be 2 mm internal diameter, but close observation with digital calipers puts it more at 2.3 mm. I tried this with some 2.6 mm internal diameter silicone hose and it did not stay on as well. I used a 50' spool of Du-BRO (2239). You can buy shorter 2 ft sections sold as Du-BRO 2231 and it also comes in lots of colors. The stuff I used was perfect; the silicone makes it grab and stay on the nozzle very well. Just make sure there is no fluid on the nozzle when you slip it on. Always be watchful so you don't spray yourself with flammable fluid. I have not yet had this happen to me, despite heavy use of this thing.
The tubing for the firing nozzle (referring here to the part that actually shoots the flame) that I really liked is made of brass. The aluminum stuff its too bendy. One of the most important things to achieving good colored flames is having a high pressure tiny nozzle. If you spray too much liquid that is not aersolized well, it will just burn the same color as an ordinary flame. In order for the colors to show, the fuel must mix well with air to burn completely.
Cut the hose and round brass tube to size as seen in the pics. Crush the end of the tube with needle-nose pliers to make a very small opening for fuel to shoot out. Make sure to sand sharp edges off the tube before inserting it into the hose. Pro tip: Insert the clean factory cut ends to into the hose.
Step 8: Make the Leather Strap
Cut leather strap as seen to 17 cm. Add sticky back velcro (best if you sew it on too). Only add enough velcro to attach the strap together and avoid having any exposed. Velcro burns, so it is best not to have any exposed. Orient the attached velcro strips on the side of the flamethrower away from the flames as shown.
Step 9: Test It Out With the Butane in the Refill Canisters
Hook up the tubes well and check for any leaks. Might as well give these a try with the butane that is already in the butane tanks. They will have to be empty to add the colorant solution. I dip the pilot light wick in Coleman camp fuel because that fuel gives a long burn time with a big flame. It's best to just get the wick wet and not go crazy over-saturating it or else some of the fluid may get all over the flamethrower and the whole thing will be on fire. Have a bucket of water, fire extinguisher, and a wet cotton towel on standby. This is an outdoor activity. A small amount of fuel will likely leak right where the brass tubes transition from the silicone tubes. It won't be liquid, but only a tiny amount of vapor. This did not cause any problems for me because of the flame guard.
Light it with a match or lighter and give it a shot. I'm firing with the wind here and it is working flawlessly without any sputtering (flame is not starting and stopping). Always be mindful of even the slightest breeze and its direction.
Step 10: Make the Special Coloring Sauce
Do all of these filling steps in a well ventilated area away from any fire sources! Wear splash glasses when filling these tanks. I've had this stuff spray me while working with it and I was glad I was wearing them. You don't want this crap in your forehead balls. I only use about a gram or fraction of a gram of ionic compounds for about every 100 mL of denatured alcohol because it takes very little to get color and more may just clog up your nozzle. Plus, some of these ionic compounds are toxic, but rather small amounts are used.
Don't use methanol alcohol (Heet). It works, but it's more toxic and allows whatever is mixed with it to diffuse through your skin. The methanol itself also goes right through your skin. It's a lot more toxic than ethanol (the alcohol in booze). There is some methanol (or a similar substance) in denatured alcohol (in some cases >10% methanol), hence why I wear the nitrile gloves when mixing this stuff. Denatured alcohol largely contains ethanol. They put something toxic like methanol and bitter substances in denatured alcohol to discourage people from drinking it (to keep sales costs down by avoiding liquor tax). Read all the included material and safety data sheets on the chemicals being used here so you know what is going on with them.
My friend and I accidentally spilled a couple of ounces of methanol and boric acid on our arms while teaming up to make a large green flamethrower (which worked great). We promptly washed it off with water, but felt a weird tingling sensation on the surface of our arms for a few hours afterwards. I don't think it was good for us, but we survived. Just be careful with these chemicals and work only with small amounts. Methanol can actually cause blindness and according to the Nation Institutes of Health, "As little as 2 tablespoons can be deadly to a child. About 2 to 8 ounces can be deadly for an adult."
I can't say that I completely know what all the products are that are produced by burning all of this stuff together. A mix of butane, denatured alcohol (which can be a mix of several things), and ionic compounds burning in air comprises a lot of chemical reactions occurring at once. In a standard scaled down version of this that a teacher would conduct in a chem lab, a butane burner may be used to burn these ionic compounds mixed with methanol alcohol, but a very small amount is used. I'm burning a big cloud of this stuff. So, there is a certain unknown risk in all this to be aware of.
Isopropyl rubbing alcohol will have crappy performance even at 99 percent purity. It doesn't burn clear enough for the colors to show through well.
Copper chloride is not a good colorant to use here since it is rather corrosive to metal and may wreck the seals on the butane tanks. I use copper acetate instead. I also avoid lithium salts. They look cool (magenta), but they're not so great for you.
Links for Material and Safety data sheets.
Denatured alcohol Kleen Strip brand (blue and red can)http://jwbasecamp.com/Articles/SuperCat2/MSDS/MSDS%20-%20SLX.pdf
This stuff has more methanol in it and overall seems more toxic than the new "green" stuff. You can read what's in it in the sheet. I used the blue can stuff for the video, but I'm starting to phase it out.
Denatured alcohol Kleen Strip (green) http://go.rockler.com/tech/RTD20000423AA.pdf
I recommend this one!
Strontium chloride http://www.sciencelab.com/msds.php?msdsId=9925107
Boric acid a.k.a. orthoboric acid http://www.sciencelab.com/msds.php?msdsId=9927105
(green/greenish yellow flame)
(Green flame) -Supposedly, have not tested yet-
Sodium chloride (Table salt)
Potassium chloride/Potassium tartarate (No Salt Salt)
(Purple/Pink/Orange flame) Could not capture this well on camera, but it looks sweet live.
Mix 1.5 grams SrCl2 to 100 mL of alcohol (red flame mix). Add .75 gram of copper acetate to 100 mL of alcohol (blue/green). 1 gram of Boric acid to 100mL of alcohol(yellow/green). With most of these I usually just eyeball this and try to get it close to this amount. I will try and update later with the effects of exact ionic compound to alcohol ratio on performance. I made my No Salt salt solution a bit more saturated and did the same with my regular salt solution.
Bright Blue flames are possible, but I will do a separate inscrutable on that topic. These butane containers would not hold up well to the chemicals required for blue fire.
Step 11: Add the Special Sauces and Butane
The syringe will have to have a section of nitro line tubing attached to it. The completely empty tanks can be put in the pocket flamethrower tank holder to make filling with the alcohol and colorant solution easier. Attach the hose snugly to the top of the mini butane refill tank nozzle. The lever on the nozzle simply needs to be pushed down and the fluid can be injected in. The container must be emptied of butane or else it will be very hard to push the fluid in and it may just wind up spraying everywhere. You can fill the butane tanks with this liquid anywhere from very little to 3/4 full. I've found that adding more tends to make the fire last longer, but doesn't make it that much more colorful. The more alcohol you have the more likely it is for the flaming liquid to make it to the ground rather than burning up in the air. This is due to the fact that butane burns up more readily. This of course makes it more dangerous for you as it keeps burning whatever gets sprayed longer.
I attached a small section of hose to the fill nozzle of the large butane refill canister that will be filling the little ones. The other end of the hose was attached to the nozzle of the little canister. The section of hose must be long enough to seal both nozzles well to prevent fuel leaking out, but short enough to not kink. Press the big canister strait down into the other one and make sure the hose isn't getting pinched and that the nozzles aren't bending. Again, make sure to use safety glasses!
I plan on retiring these little butane canisters after a couple dozen refills since they were never designed for being refilled and I don't know how many times one can do this without them starting to leak. I have yet to see any of the 9 containers I have spring a leak despite over a dozen fills with each. Always check for leaks though.
Fill up plenty of extra cartridges to make refilling quick and easy and to give yourself lots of color options.
Step 12: Become a Colored Fire Bender!
Disregard what Dr. Spengler said about crossing the streams! It works great! Remember no polyester, spandex, vinyl, nylon, or other flammable meltable clothing! No flammable hair products either! I wet my hair down just to be safe.
You will have to cross the streams to get two colors at once. If you just shoot the colors side by side, then the colors just mix together and often come out looking like ordinary yellow/orange fire. Some color combinations mixed together may work to create new colors, but the exact amount of chemicals used will play heavily into the results.
Step 13: Bonus Stuff and Looking to the Future
Included are pictures of my original single tank system. I made a lot of changes from the original. The new nozzle is much simpler, pilot light gained a cover, lever system was made smaller, and the lighter was removed from the assembly. I do have to say that I like using rectangular brass tubing better for a lever than the polycarbonate because it removes the need for those little flat washers. I think a future hybrid design between my 1st system and 2nd will yield something better all together.
I'm still working on a sparkle solution that's relatively safe, consistent, and that doesn't clog up the systems. I'm getting close, but it still needs a bit of tinkering. Certain formulations I have tried may be a bit too volatile to show others how to make. Once I get it it figured out though I'll post about it.
My double color firing system seems to work well, so next up will have to be a triple color system. Perhaps I'll make two so I can shoot six different colors at once!
I already have larger servo activated versions of this that can be controlled via cheap hacked led remotes/receivers, so stay tuned for more of this stuff!
Runner Up in the
Halloween Props Contest