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 (preferably Green Kleen Strip) -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 tie about 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
Step 3: Attaching hinges for fuel canister nozzle levers
Step 4: Making the polycarbonate canister nozzle levers
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
Step 6: Pilot light construction
Step 7: Make the high pressure firing nozzles
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
Step 9: Test it out with the butane in the refill canisters
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.
Butane Bernzomatic http://www.homedepot.com/catalog/pdfImages/9b/9b78225d-a74a-4a07-a643-bb75bc09c6c4.pdf
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)
Copper(I) Acetate http://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?country=US&language=en&productNumber=403342&brand=ALDRICH&PageToGoToURL=http%3A%2F%2Fwww.sigmaaldrich.com%2Fcatalog%2Fproduct%2Faldrich%2F403342%3Flang%3Den
(Green flame) -Supposedly, have not tested yet-
Copper(II) Acetate http://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?country=US&language=en&productNumber=326755&brand=ALDRICH&PageToGoToURL=http%3A%2F%2Fwww.sigmaaldrich.com%2Fcatalog%2Fproduct%2Faldrich%2F326755%3Flang%3Den
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
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!
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
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!