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A pyrotechnic fastener (also called an explosive bolt, or pyro, within context) is a fastener, usually a nut or bolt, that incorporates a pyrotechnic charge that can be initiated remotely. One or more explosive charges embedded within the bolt are typically activated by an electric current, and the charge breaks the bolt into two or more pieces. The bolt is typically scored around its circumference at the point(s) where the severance should occur.[1] Such bolts are often used in space applications to ensure separation between rocket stages, because they are lighter and much more reliable than mechanical latches.
Gas generators are similar to pyrotechnic fasteners. They are used to generate large amounts of gas, as for turbopumps, to inflate balloons, especially airbags, to eject parachutes and similar applications.
Various pyrotechnic compositions can be used, depending on the desired burn rate and required amount of energy and volume of gas produced. Some materials, such as RDX, sublime in vacuum, which limits their usefulness in aerospace applications.[4] Composition with the character of bipropellants and flash powders are often used.[citation needed]
RDX / nitrocellulose: Gas generator, unsuitable for deep space missions, burn rate dependent on pressure.[5]
Boron / potassium nitrate: Gas generator and rocket-motor igniter, thermally stable, stable in vacuum, burn rate independent of pressure.[5]
Zirconium / potassium perchlorate: Used in the NASA Standard Initiator (NSI).[6] Rapid pressure rise, little gas but emits hot particles, thermally stable, vacuum stable, long shelf life. Sensitive to static electricity. Known to cause circuit damage during ground testing.[5]
Lead azide: Used as a primary explosive.[7]: 38 Sensitive to impact, friction, and static electricity. Thermally and vacuum stable, if dextrin is not used for desensitizing. Long shelf life.[5]
Hexanitrostilbene: Used in detonators, linear shaped charges, and bulk explosives. Insensitive to stimuli other than explosion. Thermally stable. Vacuum stable.[5] Used in deep space applications where RDX can not be utilized, such as aboard the Apollo Lunar Module[7]: 23 Detonates at 22,000 feet per second (6,700 m/s).[5]
See alsoedit
Frangible nut, the counterpart of the explosive bolt
Referencesedit
^U.S. Army Material Command Pamphlet 706-179 - 'Explosive Trains'(PDF). U.S. Army. 9 March 1965. p. 108. (PDF) from the original on 19 August 2022.
^"AIAA 96-2874 Development and Qualification Testing of the High Voltage Detonator".
^"Laser Motor Igniter". Retrieved 12 September 2022.
^Ewing, Robert G.; Waltman, Melanie J.; Atkinson, David A.; Grate, Jay W.; Hotchkiss, Peter J. (1 January 2013). "The vapor pressures of explosives". Trends in Analytical Chemistry. 42: 35–48. doi:10.1016/j.trac.2012.09.010. Retrieved 19 August 2022.
^ abcdefgBement, Laurence J.; Schimmel, Morry L. (1 June 1995). A Manual for Pyrotechnic Design, Development and Qualification. Hampton, Virginia: NASA, Langley Research Center. pp. 14–16. Archived from the original on 22 May 2011.
^Hohmann, Carl; Tipton, Bill Jr.; Dutton, Maureen (1 October 2000). Propellant for the NASA Standard Initiator(PDF). Houston: NASA, Johnson Space Center. p. 1. (PDF) from the original on 11 April 2022.
^ abFalbo, Mario J.; Robinson, Robert L. (1 March 1973). NASA Technical Note D-7141 - Apollo Experience Report: Spacecraft Pyrotechnic Systems(PDF). NASA, Lyndon B. Johnson Space Center, Houston. (PDF) from the original on 12 December 2020.
External linksedit
Explosive bolts discussion in a mailing list
January 01, 1970
pyrotechnic, fastener, this, article, lead, section, contains, information, that, included, elsewhere, article, information, appropriate, lead, article, this, information, should, also, included, body, article, august, 2022, learn, when, remove, this, message,. This article s lead section contains information that is not included elsewhere in the article If the information is appropriate for the lead of the article this information should also be included in the body of the article August 2022 Learn how and when to remove this message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Pyrotechnic fastener news newspapers books scholar JSTOR May 2014 Learn how and when to remove this message A pyrotechnic fastener also called an explosive bolt or pyro within context is a fastener usually a nut or bolt that incorporates a pyrotechnic charge that can be initiated remotely One or more explosive charges embedded within the bolt are typically activated by an electric current and the charge breaks the bolt into two or more pieces The bolt is typically scored around its circumference at the point s where the severance should occur 1 Such bolts are often used in space applications to ensure separation between rocket stages because they are lighter and much more reliable than mechanical latches Explosive bolt in an Orion module In applications that require safety precision and reliability such as the aerospace industry 2 pyrotechnic fasteners are triggered using exploding bridgewire detonators which were themselves later succeeded by slapper detonators citation needed Classical blasting caps are generally avoided for such usage More recent developments have used pulsed laser diodes to detonate initiators through fiber optic cables 3 which subsequently fire the main charge Gas generators are similar to pyrotechnic fasteners They are used to generate large amounts of gas as for turbopumps to inflate balloons especially airbags to eject parachutes and similar applications Contents 1 Compositions used 1 1 Standard pyrotechnic mixtures used by NASA 2 See also 3 References 4 External linksCompositions used editVarious pyrotechnic compositions can be used depending on the desired burn rate and required amount of energy and volume of gas produced Some materials such as RDX sublime in vacuum which limits their usefulness in aerospace applications 4 Composition with the character of bipropellants and flash powders are often used citation needed Standard pyrotechnic mixtures used by NASA edit Manganese barium chromate lead chromate Time delay mix used for sequencing Gasless burning 5 RDX nitrocellulose Gas generator unsuitable for deep space missions burn rate dependent on pressure 5 Boron potassium nitrate Gas generator and rocket motor igniter thermally stable stable in vacuum burn rate independent of pressure 5 Zirconium potassium perchlorate Used in the NASA Standard Initiator NSI 6 Rapid pressure rise little gas but emits hot particles thermally stable vacuum stable long shelf life Sensitive to static electricity Known to cause circuit damage during ground testing 5 Lead azide Used as a primary explosive 7 38 Sensitive to impact friction and static electricity Thermally and vacuum stable if dextrin is not used for desensitizing Long shelf life 5 Hexanitrostilbene Used in detonators linear shaped charges and bulk explosives Insensitive to stimuli other than explosion Thermally stable Vacuum stable 5 Used in deep space applications where RDX can not be utilized such as aboard the Apollo Lunar Module 7 23 Detonates at 22 000 feet per second 6 700 m s 5 See also editFrangible nut the counterpart of the explosive boltReferences edit U S Army Material Command Pamphlet 706 179 Explosive Trains PDF U S Army 9 March 1965 p 108 Archived PDF from the original on 19 August 2022 AIAA 96 2874 Development and Qualification Testing of the High Voltage Detonator Laser Motor Igniter Retrieved 12 September 2022 Ewing Robert G Waltman Melanie J Atkinson David A Grate Jay W Hotchkiss Peter J 1 January 2013 The vapor pressures of explosives Trends in Analytical Chemistry 42 35 48 doi 10 1016 j trac 2012 09 010 Retrieved 19 August 2022 a b c d e f g Bement Laurence J Schimmel Morry L 1 June 1995 A Manual for Pyrotechnic Design Development and Qualification Hampton Virginia NASA Langley Research Center pp 14 16 Archived from the original on 22 May 2011 Hohmann Carl Tipton Bill Jr Dutton Maureen 1 October 2000 Propellant for the NASA Standard Initiator PDF Houston NASA Johnson Space Center p 1 Archived PDF from the original on 11 April 2022 a b Falbo Mario J Robinson Robert L 1 March 1973 NASA Technical Note D 7141 Apollo Experience Report Spacecraft Pyrotechnic Systems PDF NASA Lyndon B Johnson Space Center Houston Archived PDF from the original on 12 December 2020 External links editExplosive bolts discussion in a mailing list Retrieved from https en wikipedia org w index php title Pyrotechnic fastener amp oldid 1217900756, wikipedia, wiki, book, books, library,
