Build Your Own Flamethrower Step-by-step Manual Table of Contents: Parts List.. page 1 Operation...page 6 Diagrams. pages 7-9 Parts list: Required: Air tank (large) Pressure washer gun with high-pressure hose CO 2 tank (small) 320 CGA Female to 1/8 NPT 1 Female Adapter 1/8 male NPT to 1/8 male NPT (4 in length) Paintball ASA 7/16 drill bit Pipe tap 1/4"-18 NPT Gun oil, 2 stoke oil, or similar lubricant 1/4 hose slip fitting to 1/4 male threads (see image) Teflon tape Short hose clamps 4 minimum (2) Propane cylinder (preferably 14.1 oz) Welding Torch Long Hose clamps: 12 minimum (3) NOTE: The following instructions are for ACADEMIC USE ONLY! Do NOT attempt to build. Extreme injury or death can occur. The author(s) of this manual accept NO responsibility for ANY injury or damages to people, animals, or property. 1 National Pipe Thread 1
Gathering Your Parts: Air Tank (large) The large air tank is to your flamethrower what your gas tank is to your car. It is the holding tank for whatever liquid you will be shooting. The tank used in this build was an aluminum 15lb 2 CO 2 tank used for soda machines and beer kegs. A 20lb tank (about $15 more) will work equally as well and will provide more volume and longer firing time. If you do not know the size of your tank, you can figure it out by measuring the height from the top of the tank (not including the regulator/valve) to the base. Height will be 24 for both a 20lb and 15lb tank. The base diameter of a 15lb tank is 7 and for a 20lb tank is 8. A height shorter than 24 indicates a tank smaller than 15lbs. The 15lb tank holds approximately 2.5 gallons of liquid and will shoot for a total time of about 40 seconds. A 20lb tank will shoot closer to 1 minute. The handle on the top of the tank needs to be removed so there is room to attach the fitting that leads to the CO 2 tank. A c-clip is the only thing holding on the handle. Using c-clip pliers and possibly a flat head screwdriver, you should be able to remove it with little difficulty. These tanks come equipped with 320 CGA male threads that will need to be reduced (see next step) to attach the small CO 2 tank. 15lb and 20lb tanks available at BeverageFactory.com for $95.50 and $109.20 respectively. This tank is recommended since theses instructions provide the parts to reduce the included fitting. http://www.beveragefactory.com/draftbeer/tanks/co2.shtml If this link ever goes dead, a simple search will provide many alternatives. 320 CGA Female to 1/8 NPT Female Adapter The fitting on the tank will need to be reduced in order to attach either the CO 2 tank or compressed air tank. Simply layer the male 320 CGA CO 2 threads with 3 passes of Teflon tape. 2 The lb rating is the volume measurement for CO 2 and Nitrogen. Unlike scuba tanks, cubic feet is not used for measurement. A 15lb tank holds approximately 2.5 gallons. 2
Attach the adapter and tighten the adapter using a wrench or pliers. 1/8 Male NPT to 1/8 Male NPT (4 in length) This is a simple 1/4 diameter pipe with 1/8 NPT male threads on both ends and is used as an extension. 4 is needed to provide adequate space so the small CO 2 tank will stand vertically without touching the large one. Wrap both sides of the pipe with 1-2 passes of Teflon tape. Tighten this pipe using pliers gripped on the middle of the pipe (not the threads!). Paintball ASA This is used to attach the small CO 2 tank to the 1/8 NPT pipe. Attach to the other end of the 1/8 NPT pipe. Not all ASAs will look like the picture provided (image at right). Virtually all ASAs for paintball use will work. This piece is used to apply pressure to the nipple valve on the small CO 2 tank, letting the compressed gas pressurize the system. Available at most all paintball stores for about $15 or do a search on the web for Paintball ASA. CO 2 Tank (Small) This tank is what provides the pressure for projecting the liquid. A 20 oz CO 2 tank, commonly used for paintball guns, is recommended to ensure enough pressure is provided to maintain a consistent shot. This CO 2 tank will put out between 700-1200psi 3 depending on temperature and how full the tank is. Here are general guidelines for pressure output based on temperature (assuming outside temperature and tank temperature are equal). The tank is rated for 1800psi and the hose for over 2000psi so over pressurizing the system will not be an issue. This tank will attach at the ASA. 100 F = 1200psi 4 80 F = 950psi 60 F = 700psi A 20oz CO 2 tank is available in any paintball store as well as most sporting goods stores such at Sport Chalet for around $20-25. Pipe Tap 1/4"-18 NPT and 7/16 Drill Bit Since your CO 2 tank will not have a hole to attach the pressure washer hose, you will need to make your own. Drill a 7/16 hole on the side of the tank, 2 from the bottom of the tank to avoid drilling into the 3 Pounds per square inch 4 All pressure ratings are approximations based on temperature. Other factors such as elevation, humidity, and barometric pressure can affect pressure. 3
base (right image). Once the hole is drilled, you need to cut the threads. To properly cut the threads, you will need some kind of lubricant such as gun oil or motor oil to disperse heat and ensure smooth and complete threads are cut. Using the 1/4"-18 NPT tap with the tap and die kit (see image below) begin cutting the threads slowly by inserting the tap into the hole and turning clockwise 1/8-1/4 of a turn then backing out the tap slightly to allow the cut metal shards to clear the newly cut grooves. Lubricate often. Cut using the entire length of the tap to ensure the grooves are properly cut. Once the whole is drilled and tapped, rinse out the tank with water to remove the metal shards. Tap and die kits can be found at most major hardware stores. When purchasing, be sure the tap is for NPT threads since there are other sizes available. Even though we are using a 1/4 tap, you may notice that the diameter of the tap is 1/2. We know this, there is no typing error, it is just the way the NPT threads are measured. 1/4 Hose Slip Fitting to 1/4 Male Threads NPT Once the hole is cut, cover the threads of the hose fitting with 2 passes of Teflon tape and thread into the hole. Tighten using a 9/16 wrench. This Husky 1/4 hose repair kit (right image) includes the necessary fitting and hose clamps. The doublesided slip fitting will not be used. This kit can be found at Home Depot or other hardware stores for under $4. Pressure Washer Gun with High-Pressure Hose The gun of this flamethrower is the same gun that is used with a pressure washer. It s important that a pressure washer gun is used since most have metal internals that won t corrode (like plastic will) upon contact with the fuel. A pressure-washer gun can be purchased 4
usually with the high-pressure hose included at most major hardware stores or on the web for around $20-40. One end of the high-pressure hose will attach to the pressure washer gun; the other end will be set up to attach to the pressure washer. A pressure washer is not being used for this build so cut that end off so the hose is the desired length (6 was used for this build). Push the hose onto the 1/4 hose fitting (if this is difficult, soak the end of the hose in boiling water for about 10 seconds to soften it) on the side of the tank and secure it using 2 of the included small hose clamps. Be sure to use both for extra strength. Propane Cylinder To light the fuel, you will need a source of ignition. The best way to light a stream of flammable liquid is with a pilot flame. The propane cylinder we used was a 14.1oz propane tank and is recommended for it s long and slender size. Bernzomatic makes a great quality tank and is what was used for this build. Available for around $4-5 at any hardware store Propane was used for this build but any flammable gas such as map gas will suffice. Welding Torch The welding torch used for this build was the Bernzomatic JTH7 Welding Torch with 4 flexible hose. Another torch may be used as long as it can be positioned under the pressure washer gun to provide a pilot flame. The soft hose is a key asset to this task. Three 12 hose clamps are needed to secure the propane cylinder and torch to the pressure washer gun (see diagram). This torch available at most major hardware stores such as Home Depot or Harbor Freight for around $20. Also may be purchased on the web. 5
Operation: NOTE: The authors of this manual do not take responsibility for ANY consequences due to use or misuse of this flamethrower. 1) Begin by removing the top of the large CO 2 tank. The entire top piece, which includes the 320 male threads, should unscrew relatively easily. Leverage tools may be applied if you cannot unscrew with your hands. Fill the entire volume of the tank with the desired liquid or fuel. 2) Once filled, seal the large tank with the same piece that was removed. Ensure that the o-ring at the base of the threads is in good condition before each use. Tighten snugly; hand tightening should be enough if you use the ASA as a fulcrum for leverage. Ensure that the on/off valve on the top of the large tank is closed (turned clockwise) before attaching the small CO 2 tank. 3) Attach the small CO 2 tank at the ASA until you hear the gas fill the fittings. The tank will be considerably more difficult to tighten at this point. 4) Open the on/off valve on the top of the large tank slowly. You will hear the gas filling what space is left in the large tank. 5) Turn on the pilot flame. Open the valve to the propane tank and light the flame using a spark or other fire source. 6) At this point your flamethrower is ready for use. Do not shoot at people or animals! 7) After the liquid has been depleted from the tank, turn of the pilot flame and close the on/off valve by turning it counter clockwise until it stops. Remove the CO 2 tank from the ASA. A small amount of gas may escape while you are unscrewing the tank. The tank will be very cold from the CO 2 expansion. The range of this flamethrower is approximately 45 feet. 6
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