In pyrotechnics, a pyrotechnic initiator (also initiator or igniter) is a device containing a pyrotechnic composition used primarily to ignite other, more difficult-to-ignite materials, such as thermites, gas generators, and solid-fuel rockets. The name is often used also for the compositions themselves.
Pyrotechnic initiators are often controlled electrically (called electro-pyrotechnic initiators), e.g. using a heated bridgewire or a bridge resistor. They are somewhat similar to blasting caps or other detonators, but they differ in that there is no intention to produce a shock wave. An example of such pyrotechnic initiator is an electric match.
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Transcription
For this video, I’m going to show you how to make a handful of remote controlled, electric ignitors from things you already have around the house. That will ignite fireworks safely, and from a distance. Or launch your homemade rockets, with the simple press of a button. To start this project, you’ll just need a book of paper matches, some tape, and an old cell phone charger. Chances are you have a spare charger somewhere in the house, but if not, you can easily find them at thrift stores for about a dollar. Now get to work with a pair of scissors, and carefully chop the head and charge controller off of the cable, then cut it up into smaller pieces around 2” long. If we remove the outer jacket, you can see there are two insulated wires inside, made of very thin, stranded copper wires. And for this project, the thinner the wires are, the better the ignitors will work. Now we don’t need the outer sheathing at all, so go ahead and pull the wires out and strip the other ends down about half an inch. Carefully single out one copper strand, from the bundle of wire, and pull it to off the side. And now the other frayed wires, are all garbage, so just twist them together, and use a pair of scissors to snip them off at the base. Now let’s take a close look at the other wire. If it has nylon cording mixed in with the copper strands you need to get rid of it. And the most effective way to eliminate it, is to lick it with a flame from a candle, or a BBQ ignitor. Now hold the two cables side by side about 1/4” apart, then twist the bridge wire from the first cable, so it binds together tightly, and meshes in with the other strands. This will ensure the bridge wire has great electrical contact, and should prevent it from unravelling. To hold the wires in place, simply lay a small piece of tape on the table, so it’s facing sticky side up, and press the wires down into the center. Now make sure the bridge wire is poking out around 1/4” from the top, then bend the excess wire back, and press it down beside the wires on the inside. Alright the ignitor leads are completed, so let’s take a quick break from all that, and spend some time modifying the match heads. Take the matches, one at a time, and carefully slide them down the edge of a sharp pair of scissors. You can see it scores a very small grove, right down the center of the tip. Now bring back the ignitor leads, and line the bridge wire up with the groove in the match-head, and secure it firmly in place by wrapping one side of the tape tightly over the base of the match, then reinforce it again, by firmly wrapping the other half of the tape the other direction. For one finishing touch, it’s good practice to burn the nylon strands on the ignitor leads as well, then twist them together tightly so they’ll make better contact. At this point, your electric match is finished, and ready to go to work. To test them out, I tried connecting alligator clips to the leads of the ignitor, then running the wires to two 9 volt batteries, in parallel. Now all it takes for ignition, is the press of a button to complete the circuit. Or in this case, a touch of the wires to the battery terminals. The matches light off because when the circuit is completed, over 6 amps of electrical current surge through the tiny bridge wire on top, and the electricity gets the wire so hot it ignites the chemicals in the match head, causing it to burst into flames. And you can see that all happens very quickly. Now just for fun, I got an old N64 controller and converted it, into a rocket launch controller. So now I can launch homemade sugar rockets with the the press of a button. Look for how I made this in another project video. Well now you know how to mass produce electric ignitors, with junk you probably have lying around the house. By the way, if you try using different colored tape, you can give your ignitors your own custom touch. And if you can’t find paper matches, wooden matches will work just as well. Well that’s it for now. If you like this video, perhaps you’ll like some of my others. Check them out at www.thekingofrandom.com
Composition
The energetic material used, often called pyrogen, is usually a pyrotechnic composition made of a fuel and oxidizer, where the fuel produces a significant amount of hot particles that cause/promote the ignition of the desired material.
Initiator compositions are similar to flash powders, but they differ in burning speed, as explosion is not intended, and have intentionally high production of hot particles. They also tend to be easier to ignite than thermites, with which they also share similarities.
Common oxidizers used are potassium perchlorate and potassium nitrate. Common fuels used are titanium, titanium(II) hydride, zirconium, zirconium hydride, and boron. The size of the fuel particles is determined to produce hot particles with the required burning time.
More exotic materials can be used, e.g. carboranes.[1]
For special applications, pyrophoric igniters can be used which burst into flame in contact with air. Triethylborane/TEA-TEB was used as an igniter for the Lockheed SR-71 jet engines, the Rocketdyne F-1 engine on the first stage of the Saturn V, NPO Energomash's RD-180 engine used on the first stage of the Atlas V, and SpaceX's Merlin engine used on the first stage of the Falcon 9.
Common compositions
Metal-oxidizer
ZPP
One of the most common initiators is ZPP, or zirconium – potassium perchlorate – a mixture of metallic zirconium and potassium perchlorate. This mixture is used in the NASA Standard Initiator,[2] which is used to ignite various pyrotechnic systems, including the NASA standard detonator.[3] It yields rapid pressure rise, generates little gas, emits hot particles when ignited, is thermally stable, has long shelf life, and is stable under vacuum. It is sensitive to static electricity.
BPN
Another common igniter formula is BPN, BKNO3, or boron – potassium nitrate, a mixture of 25% boron and 75% potassium nitrate by weight. It is used e.g. by NASA. It is thermally stable, stable in vacuum, and its burn rate is independent of pressure.
In comparison with black powder, BPN burns significantly hotter and leaves more of solid residues, therefore black powder is favored for multiple-use systems.
BPN's high temperature makes it suitable for uses where rapid and reproducible initiation is critical, e.g. for airbags, rocket engines, and decoy flares. It is however relatively expensive.
BPN can be also used as an ingredient of solid rocket propellants.[4]
BPN can be ignited by a laser.[5] A semiconductor laser of at least 0.4 watts output can be used for ignition in vacuum.[6]
Others
Other mixtures encountered are aluminium-potassium perchlorate and titanium-aluminium-potassium perchlorate.[7]
Metal hydride-oxidizer
Metal hydride-oxidizer mixtures replace the metal with its corresponding hydride. They are generally safer to handle than the corresponding metal-oxidizer compositions. During burning they also release hydrogen, which can act as a secondary fuel. Zirconium hydride, titanium hydride, and boron hydride are commonly used.
ZHPP
ZHPP (zirconium hydride – potassium perchlorate) is a variant of ZPP that uses zirconium hydride instead of pure zirconium. It is significantly safer to handle than ZPP.[8]
THPP
THPP (titanium hydride potassium perchlorate) is a mixture of titanium(II) hydride and potassium perchlorate. It is similar to ZHPP. Like ZHPP, it is safer to handle than titanium-potassium perchlorate.[8]
Intermetallics
Formation of an intermetallic compound can be a strongly exothermic reaction, usable as an initiator.
Titanium-boron
Titanium-boron composition is one of the hottest pyrotechnic reactions in common usage. It is solid-state, gasless. It can be used as a pyrotechnic initiator or for heating confined gas to perform mechanical work.[9]
Nickel-aluminium
Nickel-aluminium laminates can be used as electrically initiated pyrotechnic initiators. NanoFoil is such material, commercially available.
Palladium-aluminium
Palladium-clad aluminium wires can be used as a fuse wire, known as Pyrofuze.[10] The reaction is initiated by heat, typically supplied by electric current pulse. The reaction begins at 600 °C, the melting point of aluminium, and proceeds violently to temperature of 2200–2800 °C. The reaction does not need presence of oxygen, and the wire is consumed.[11]
Pyrofuze comes as a solid wire of different diameters (from 0.002" to 0.02"), braided wire, ribbon, foil, and granules. Palladium, platinum, or palladium alloyed with 5% ruthenium can be used together with aluminium.[12][13] Pyrofuze bridgewires can be used in squibs and electric matches. Pyrofuze foils can be used for e.g. sealing of various dispensers or fire extinguishing systems.[14] Palladium-magnesium composition can also be used, but is not commercially available or not at least as common.[15]
Others
BNCP
BNCP, (cis-bis-(5-nitrotetrazolato)tetraminecobalt(III) perchlorate) is another common initiator material. It is relatively insensitive. It undergoes deflagration to detonation transition in a relatively short distance, allowing its use in detonators. Its burning byproducts are of relatively little harm to environment.[16] It can be ignited by a laser diode.
Lead azide
Lead azide (Pb(N3)2, or PbN6) is occasionally used in pyrotechnic initiators.
Others
Other materials sensitive to heat can be used as well, e.g. HMTD,[17] tetrazene explosive, lead mononitro-resorcinates, lead dinitro-resorcinates, and lead trinitro-resorcinates.[18]
See also
References
- ^ EP expired 1128994B1, Karl K. Rink, "Carborane-containing airbag inflator", published 2001-09-05, issued 2004-08-11, assigned to Autoliv ASP Inc.
- ^ Applications catalog of pyrotechnically actuated devices/systems (PDF). Cleveland, OH: NASA Lewis Research Center. 1 January 1995. pp. 66–67. Archived from the original (PDF) on 22 August 2022.
- ^ Proceedings of Electric Initiator Symposium - 1963. Franklin Institute, Philadelphia, Pennsylvania: U.S. Army Materiel Command. 1 October 1963. pp. 3–17. Archived from the original (PDF) on 28 May 2018.
- ^ "Video - Product Compliance Explained". Sphera. 2021-04-12. Retrieved 2021-09-30.
- ^ ES expired 2160485B1, Blanes Mira Maria Clara; Carbonell Castell Teresa; Fernandez Ballester Gregorio J; Ferrer Montiel Antonio Vicente; Gil Tebar Ana Isabel; Gutierrez Perez Luis Miguel; Llobregat Hernandez M Mercedes; Perez Paya Enrique; Planell Cases Rosa M; Viniegra Bover Salvador, "Neuron exocytosis inhibitory peptide and cosmetic and pharmaceutical compositions containing the peptide", published 2001-11-01, issued 2002-05-16, assigned to Lipotec SA
- ^ Koizumi, Hiroyuki; Nakano, Masakatsu; Inoue, Takayoshi; Watanabe, Masashi; Komurasaki, Kimiya; Arakawa, Yoshihiro (2006). "Study on laser ignition of boron/potassium nitrate in vacuum" (PDF). Science and Technology of Energetic Materials. 67 (6): 193–198.
- ^ US expired 4391196, Robert E. Betts, "Add-on igniter for pyrogen type igniter", published 1983-07-05, issued 1983-07-05, assigned to US Department of Army
- ^ a b US expired 6117254, Karl K. Rink, William B. Richardson, David J. Green, "Initiator for airbag inflation gas generation via dissociation", published 2000-09-12, issued 2000-09-12, assigned to Autoliv ASP Inc.
- ^ Begeal, D. R.; Munger, A. C. Titanium-boron mixtures as variable heat sources. Sandia National Lab., Albuquerque, USA.
- ^ "PYROFUZE®" (PDF). Sigmund Cohn Corp. Archived from the original (PDF) on 2011-07-16.
- ^ Joppa, Richard M. (1974). Improved Hot-Wire Electroexplosive Devices (Report). Los Alamos Scientific Laboratory of the University of California. Retrieved 2021-09-30.
- ^ US expired 4208967, Robert E. Betts, "Squib design", published 1991-08-06, issued 1991-08-06, assigned to US Department of Army
- ^ US expired 5036769, James M. Schaff, Amos J. Diede, "Pyrofuze pin for ordnance activation", published 1983-07-05, issued 1983-07-05, assigned to US Department of Navy
- ^ Carignan, D. J.; Willian, L. (1978-01-03). Containment and Release Device for Fluids (Report). Department of the Air Force. Archived from the original on September 30, 2021.
- ^ US expired 3889755, Byron G Dunn, "Electrical appliance fire extinguisher", published 1975-06-17, issued 1975-06-17, assigned to Fire Fox Corp.
- ^ US patent 6672215, Sami Daoud, "Constant output high-precision microcapillary pyrotechnic initiator", published 2004-01-06, issued 2004-01-06, assigned to Textron Innovations Inc.
- ^ "How to Create an ANNM Detonator from scratch". Pyronfo. 2009-07-01. Archived from the original on 2016-03-09.
- ^ US expired 5942717, Claude Pathe, Raphael Trousselle, "Electro-pyrotechnic initiator, method for making same, and vehicle safety system", published 1999-08-24, issued 1999-08-24, assigned to Davey Bickford SAS
This page was last edited on 21 October 2022, at 19:06