Editing Detonator

{{Short description|Small explosive device used to trigger a larger explosion}}
{{Other uses}}
{{multiple issues|
{{More citations needed|date=June 2015}}
{{citation style|date=October 2023}}
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[[File:Detonator.jpg|thumb|Top: small [[nonel]] detonator with 2 ms delay for chaining nonel tubes; middle: class B SPD detonator; bottom: class C SPD detonator]]
[[File:Eod2.jpg|thumb|Inserting detonators into blocks of [[C-4 explosive]]]]

A '''detonator'''  is a device used to make an explosive or explosive device explode.<ref>{{Cite web |date=2024-07-28 |title=Definition of DETONATOR |url=https://www.merriam-webster.com/dictionary/detonator |access-date=2024-08-10 |website=www.merriam-webster.com |language=en}}</ref> Detonators come in a variety of types, depending on how they are initiated (chemically, mechanically, or electrically) and details of their inner working, which often involve several stages. Types of detonators include non-electric and electric. Non-electric detonators are typically stab or [[Pyrotechnics|pyrotechnic]] while electric are typically "hot wire" (low voltage), exploding bridge wire (high voltage) or explosive foil (very high voltage).<ref>{{Cite web |last1=Oyler |first1=Karl |last2=Mehta |first2=Neha |last3=Cheng |first3=Gartung |date=2015-11-01 |title=Overview of Explosive Initiators |url=https://apps.dtic.mil/sti/pdfs/ADA625185.pdf |url-status=live |archive-url=https://web.archive.org/web/20220402095032/https://apps.dtic.mil/sti/pdfs/ADA625185.pdf |archive-date=2022-04-02 |access-date=2024-08-09 |website=Defense Technical Information Center}}</ref><ref>{{Cite report |url=https://www.osti.gov/biblio/1663169 |title=PETN Exploding Bridgewire (EBW) Detonators: A Review |last=Neal |first=William |date=2020-09-18 |publisher=Los Alamos National Laboratory (LANL), Los Alamos, NM (United States) |issue=LA-UR-20-27352 |osti=1663169 |language=English}}</ref>

The original electric detonators invented in 1875 independently by Julius Smith and Perry Gardiner used [[mercury fulminate]] as the [[primary explosive]]. Around the turn of the century performance was enhanced in the Smith-Gardiner blasting cap by the addition of 10-20% [[potassium chlorate]].<ref>{{Cite book |last=Cooper |first=Paul |title=Explosives Engineering |date=1996 |publisher=Wiley |isbn=0-471-18636-8 |pages=337–339 |language=EN}}</ref> This compound was superseded by others: [[lead azide]], [[lead styphnate]], some [[aluminium]], or other materials such as DDNP ([[diazo dinitro phenol]]) to reduce the amount of lead emitted into the atmosphere by mining and quarrying operations. They also often use a small amount of [[trinitrotoluene|TNT]] or [[tetryl]] in military detonators and [[PETN]] in commercial detonators.

==History==
The first blasting cap or detonator was demonstrated in 1745 when British physician and apothecary [[William Watson (scientist)|William Watson]] showed that the [[electric spark]] of a [[Electrostatic generator#Friction machines|friction machine]] could ignite black powder, by way of igniting a flammable substance mixed in with the black powder.<ref>{{cite journal|last1=Watson|first1= William |date=1744|url=https://www.biodiversitylibrary.org/item/204890#page/639/mode/1up |title=Experiments and observations tending to illustrate the nature and properties of electricity|journal=Philosophical Transactions of the Royal Society of London|volume=43|issue= 477 |pages=  481–501|doi=10.1098/rstl.1744.0094|doi-access=free}} [https://www.biodiversitylibrary.org/item/204890#page/658/mode/1up From p. 500:] "But I can, at pleasure, fire gunpowder, and even discharge a musket, by the power of electricity, when the gunpowder has been ground with a little camphor, or with a few drops of some inflammable chemical oil."</ref>

In 1750, [[Benjamin Franklin]] in Philadelphia made a commercial blasting cap consisting of a paper tube full of [[black powder]], with wires leading in both sides and wadding sealing up the ends.  The two wires came close but did not touch, so a large electric spark discharge between the two wires would fire the cap.<ref>Franklin, Benjamin, ''Experiments and Observations on Electricity at Philadelphia in America'' (London, England: Francis Newberg, 1769), p. 92.  [https://books.google.com/books?id=-48_AAAAcAAJ&pg=PA92 From p. 92:] "A small cartridge is filled with dry powder, hard rammed, so as to bruise some of the grains; two pointed wires are then thrust in, one at each end, the points approaching each other in the middle of the cartridge till within the distance of half an inch [1.27 cm]; then, the cartridge being placed in the circle [i.e., circuit], when the four [[Leyden jar|[Leyden] jars]] are discharged, the electric flame leaping from the point of one wire to the point of the other, within the cartridge amongst the powder, ''fires it'', and the explosion of the powder is at the same instant with the crack of the discharge."</ref>

In 1832, a hot wire detonator was produced by American chemist [[Robert Hare (chemist)|Robert Hare]], although attempts along similar lines had earlier been attempted by the Italians Volta and Cavallo.<ref>{{cite web|url=http://www.standingwellback.com/home/2012/11/18/inventing-detonators.html|title=Standing Well Back - Home - Inventing detonators|website=www.standingwellback.com|date=18 November 2012|access-date=22 March 2018}}</ref>  Hare constructed his blasting cap by passing a multistrand wire through a charge of gunpowder inside a tin tube; he had cut all but one fine strand of the multistrand wire so that the fine strand would serve as the hot bridgewire. When a strong current from a large battery (which he called a "deflagrator" or "calorimotor") was passed through the fine strand, it became incandescent and ignited the charge of gunpowder.<ref>Hare, Robert (1832) [https://books.google.com/books?id=kAoAAAAAMAAJ&pg=PA266 "Application of galvanism to the blasting of rocks,"] ''The Mechanics' Magazine'', '''17''':  266–267.</ref><ref>Note: Robert Hare had constructed his large battery (or "deflagrator" or "calorimotor", as he called it) in 1821. See: Hare, R. (1821) [https://www.biodiversitylibrary.org/item/51988#page/115/mode/1up "A memoir on some new modifications of galvanic apparatus, with observations in support of his new theory of galvanism,"] ''The American Journal of Science and Arts'', '''3''':  105–117.</ref>

In 1863, [[Alfred Nobel]] realized that although nitroglycerin could not be detonated by a fuse, it could be detonated by the explosion of a small charge of gunpowder, which in turn was ignited by a fuse.<ref>Patent for nitroglycerin: Nobel, A., British patent no. 1,813 (July 20, 1864).</ref> Within a year, he was adding [[mercury fulminate]] to the gunpowder charges of his detonators, and by 1867 he was using small copper capsules of mercury fulminate, triggered by a fuse, to detonate nitroglycerin.<ref>See:
* Patent for dynamite: Nobel, Alfred, English patent no. 1,345 (May 7, 1867).
* Nobel, Alfred, [http://pdfpiw.uspto.gov/.piw?Docid=00078317&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0078317.PN.%2526OS%3DPN%2F78317%2526RS%3DPN%2F78317&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Improved explosive compound"] {{Webarchive|url=https://web.archive.org/web/20170403194839/http://pdfpiw.uspto.gov/.piw?Docid=00078317&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0078317.PN.%2526OS%3DPN%2F78317%2526RS%3DPN%2F78317&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page |date=2017-04-03 }}, U.S. patent no. 78,317 (May 26, 1868). (See p. 2 for the description of the "percussion-cap".)
* de Mosenthal, Henry (1899) [https://books.google.com/books?id=WyEAAAAAMAAJ&pg=PA443 "The life-work of Alfred Nobel,"] ''Journal of the Society of Chemical Industry'', '''18''':  443–451; see p. 444.</ref>

In 1868, Henry Julius Smith of Boston introduced a cap that combined a spark gap ignitor and mercury fulminate, the first electric cap able to detonate dynamite.<ref>Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?docid=00079268&PageNum=2&IDKey=1204F9662960&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1%2526Sect2=HITOFF%2526p=1%2526u=/netahtml/PTO/search-bool.html%2526r=1%2526f=G%2526l=50%2526d=PALL%2526S1=0079268.PN.%2526OS=PN/79268%2526RS=PN/79268 "Improvement in electric fuses,"] {{Webarchive|url=https://web.archive.org/web/20210831235521/https://pdfpiw.uspto.gov/.piw?docid=00079268&PageNum=2&IDKey=1204F9662960&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0079268.PN.%2526OS%3DPN%2F79268%2526RS%3DPN%2F79268 |date=2021-08-31 }} U.S. Patent no. 79,268 (June 23, 1868).</ref>

In 1875, Smith—and then in 1887, Perry G. Gardner of North Adams, Massachusetts—developed electric detonators that combined a hot wire detonator with mercury fulminate explosive.<ref>Cooper, Paul W., ''Explosives Engineering'' (New York, New York:  Wiley-VHC, 1996), p. 339.</ref><ref>See:
* Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?Docid=00173681&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0173681.PN.%2526OS%3DPN%2F173681%2526RS%3DPN%2F173681&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Improvement in electric fuses,"] {{Webarchive|url=https://web.archive.org/web/20170404042926/http://pdfpiw.uspto.gov/.piw?Docid=00173681&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0173681.PN.%2526OS%3DPN%2F173681%2526RS%3DPN%2F173681&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page |date=2017-04-04 }} U.S. Patent no. 173,681 (February 15, 1876).
* Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?Docid=00225173&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0225173.PN.%2526OS%3DPN%2F225173%2526RS%3DPN%2F225173&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Electric fuse,"] {{Webarchive|url=https://web.archive.org/web/20210831114635/https://pdfpiw.uspto.gov/.piw?Docid=00225173&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0225173.PN.%2526OS%3DPN%2F225173%2526RS%3DPN%2F225173&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page |date=2021-08-31 }} U.S. Patent no. 225,173 (March 2, 1880).</ref><ref>Gardner, Perry G., [http://pdfpiw.uspto.gov/.piw?docid=00377851&PageNum=1&IDKey=8E65968AE52D&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1%2526Sect2=HITOFF%2526p=1%2526u=/netahtml/PTO/search-bool.html%2526r=1%2526f=G%2526l=50%2526d=PALL%2526S1=0377851.PN.%2526OS=PN/377851%2526RS=PN/377851 "Electric fuse,"] {{Webarchive|url=https://web.archive.org/web/20170404042924/http://pdfpiw.uspto.gov/.piw?docid=00377851&PageNum=1&IDKey=8E65968AE52D&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0377851.PN.%2526OS%3DPN%2F377851%2526RS%3DPN%2F377851 |date=2017-04-04 }} U.S. Patent no. 377,851 (February 14, 1888).</ref> These were the first generally modern type blasting caps. Modern caps use different explosives and separate primary and secondary explosive charges, but are generally very similar to the Gardner and Smith caps.

Smith also invented the first satisfactory [[blasting machine|portable power supply for igniting blasting caps]]: a [[Ignition magneto|high-voltage magneto]] that was driven by a [[rack and pinion]], which in turn was driven by a T-handle that was pushed downwards.<ref>See:
* Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?Docid=00201296&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D0201,296.PN.%2526OS%3DPN%2F0201,296%2526RS%3DPN%2F0201,296&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Improvement in magneto-electric machines,"] {{Webarchive|url=https://web.archive.org/web/20220505132754/https://pdfpiw.uspto.gov/.piw?Docid=00201296&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D0201%2C296.PN.%2526OS%3DPN%2F0201%2C296%2526RS%3DPN%2F0201%2C296&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page |date=2022-05-05 }} U.S. Patent no. 201,296 (January 17, 1878).
* Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?Docid=00353827&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0353827.PN.%2526OS%3DPN%2F353827%2526RS%3DPN%2F353827&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Dynamo-electric igniting machine,"] {{Webarchive|url=https://web.archive.org/web/20220505132754/https://pdfpiw.uspto.gov/.piw?Docid=00353827&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0353827.PN.%2526OS%3DPN%2F353827%2526RS%3DPN%2F353827&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page |date=2022-05-05 }} U.S. Patent no. 353,827 (December 7, 1886).
* Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?Docid=00534289&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0534289.PN.%2526OS%3DPN%2F534289%2526RS%3DPN%2F534289&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Art of blasting,"] {{Webarchive|url=https://web.archive.org/web/20220505132756/https://pdfpiw.uspto.gov/.piw?Docid=00534289&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0534289.PN.%2526OS%3DPN%2F534289%2526RS%3DPN%2F534289&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page |date=2022-05-05 }} U.S. Patent no. 534,289 (February 19, 1895).
* Krehl, Peter O. K., ''History of Shock Waves, Explosions and Impact: A Chronological and Biographical Reference'' (Berlin, Germany:  Springer, 2009), p. 365.</ref>

Electric match caps were developed in the early 1900s in Germany, and spread to the US in the 1950s when [[Imperial Chemical Industries|ICI International]] purchased Atlas Powder Co. These match caps have become the predominant world standard cap type.

== Purpose ==

The need for detonators such as blasting caps came from the development of safer [[Secondary explosive|secondary]] and [[Tertiary explosive|tertiary explosives]] . Secondary and tertiary explosives are typically initiated by an [[Explosive train|explosives train]] starting with the detonator.  For safety, detonators and the main explosive device are typically only joined just before use.

== Design ==

A detonator is usually a multi stage device, with three parts:
# at the first stage, the initiation mean (fire, electricity, etc.) must provide enough energy (as heat or mechanical shock) to activate
# an easy-to-ignite [[primary explosive]], which in turn detonates
# a small amount of a more powerful [[secondary explosive]], directly in contact with the primary, and called "base" or "output" explosive, able to carry out the detonation through the casing of the detonator to the main explosive device to activate it.

Explosives commonly used as primary in detonators include [[lead azide]], [[lead styphnate]], [[tetryl]], and [[Diazodinitrophenol|DDNP]]. Early blasting caps also used silver fulminate, but it has been replaced with cheaper and safer primary explosives. Silver azide is still used sometimes, but very rarely due to its high price.

It is possible to construct a Non Primary Explosive Detonator (NPED) in which the primary explosive is replaced by a flammable but non-explosive mixture that propagates a shock wave along a tube into the secondary explosive. NPEDs are harder to accidentally trigger by shock and can avoid the use of lead.<ref>’’[https://publish-almego.ecoonline.net/getfile/E086791B-1CD3-4F32-A55C-D35B675FA7F6/pdf/804708/804708_Orica%20UK%20Limited_Exel%20Neo%20(1.4S)_GB-en_v1_0 Safety Data Sheet: Exel Neo (1.4S)]’’.  Orica UK Limited.  11/09/2023 rev. 1.0.</ref>

As secondary "base" or "output" explosive, [[trinitrotoluene|TNT]] or [[tetryl]] are typically found in military detonators and [[PETN]] in commercial detonators.

While detonators make explosive handling safer, they are hazardous to handle since, despite their small size, they contain enough explosive to injure people; untrained personnel might not recognize them as explosives or wrongly deem them not dangerous due to their appearance and handle them without the required care.

== Types ==

Ordinary detonators usually take the form of ignition-based explosives. While  they are mainly used in commercial operations, ordinary detonators are still used in military operations. This form of detonator is most commonly initiated using a [[safety fuse]], and used in non time-critical detonations e.g. [[Bomb disposal#UXO|conventional munitions disposal]]. Well known detonators are [[Lead(II) azide|lead azide]] [Pb(N<sub>3</sub>)<sub>2</sub>], [[silver azide]] [AgN<sub>3</sub>] and [[Mercury(II) fulminate|mercury fulminate]] [Hg(ONC)<sub>2</sub>].

There are three categories of electrical detonators: instantaneous electrical detonators (IED), short period delay detonators (SPD) and long period delay detonators (LPD). SPDs are measured in milliseconds and LPDs are measured in seconds. In situations where nanosecond accuracy is required, specifically in the implosion charges in [[nuclear weapon]]s, [[exploding-bridgewire detonator]]s are employed. The initial shock wave is created by vaporizing a length of a thin wire by an [[electric discharge]]. A new development is a [[slapper detonator]], which uses thin plates accelerated by an electrically exploded wire or foil to deliver the initial shock. It is in use in some modern weapons systems. A variant of this concept is used in mining operations, when the foil is exploded by a [[laser]] pulse delivered to the foil by [[optical fiber]].

<gallery>
File:Trimming platinum wires at Hercules Port Ewen plant 2012 017 b2f37 gb19f642h.tiff | Trimming platinum wires for use in blasting caps, 1955
File:Dorothy Locke Production of blasting caps 2012 017 b2f37 x346d4806.tiff |Production of blasting caps, [[Hercules Inc.|Hercules Powder Company]], 1955
File:Insertion of plug and bridge wire into electric blasting caps 2012 017 b2f37 8623hz26t.tiff | Inserting plug and bridge wire into electric blasting caps, 1955
</gallery>

A non-electric detonator is a shock tube detonator designed to initiate explosions, generally for the purpose of demolition of buildings and for use in the blasting of rock in mines and quarries. Instead of electric wires, a hollow plastic tube delivers the firing impulse to the detonator, making it immune to most of the hazards associated with stray electric current. It consists of a small diameter, three-layer plastic tube coated on the innermost wall with a reactive explosive compound, which, when ignited, propagates a low energy signal, similar to a dust explosion. The reaction travels at approximately 6,500&nbsp;ft/s (2,000&nbsp;m/s) along the length of the tubing with minimal disturbance outside of the tube. Non-electric detonators were invented by the Swedish company Nitro Nobel in the 1960s and 1970s, and launched to the demolitions market in 1973.

In civil mining, electronic detonators have a better precision for delays. Electronic detonators are designed to provide the precise control necessary to produce accurate and consistent blasting results in a variety of blasting applications in the mining, quarrying, and construction industries. Electronic detonators may be programmed in millisecond or sub-millisecond increments using a dedicated programming device.

Wireless electronic detonators are beginning to be available in the civil mining market.<ref>{{Cite web|url=http://www.oricaminingservices.com/us/en/page/products_and_services/electronic_blasting_systems/webgen/improving_safety_and_productivity|title=Improving safety and productivity|website=www.oricaminingservices.com|access-date=2019-05-16}}</ref> Encrypted radio signals are used to communicate the blast signal to each detonator at the correct time. While currently expensive, wireless detonators can enable new mining techniques as multiple blasts can be loaded at once and fired in sequence without putting humans in harm's way.

A number 8 test blasting cap is one containing 2 grams of a mixture of 80 percent mercury fulminate and 20 percent potassium chlorate, or a blasting cap of equivalent strength. An equivalent strength cap comprises 0.40-0.45 grams of PETN base charge pressed in an aluminum shell with bottom thickness not to exceed to 0.03 of an inch, to a specific gravity of not less than 1.4 g/cc, and primed with standard weights of primer depending on the manufacturer.[https://www.law.cornell.edu/cfr/text/27/555.11]

== Blasting caps ==
[[File:Cutaway diagram of various types of blasting caps and detonators.svg|thumb|Cutaway diagram of various types of blasting caps and detonators]]

The oldest and simplest type of cap, fuse caps are a metal cylinder, closed at one end.  From the open end inwards, there is first an empty space into which a pyrotechnic [[fuse (explosive)|fuse]] is inserted and crimped, then a pyrotechnic ignition mix, a [[primary explosive]], and then the main detonating explosive charge. The primary hazard of pyrotechnic blasting caps is that for proper usage, the fuse must be inserted and then crimped into place by crushing the base of the cap around the fuse.  If the tool used to crimp the cap is used too close to the explosives, the primary explosive compound can detonate during crimping.  A common hazardous practice is crimping caps with one's teeth; an accidental detonation can cause serious injury to the mouth. Fuse type blasting caps are still in active use today.  They are the safest type to use around certain types of electromagnetic interference, and they have a built in time delay as the fuse burns down.

Solid pack electric blasting caps use a thin [[bridgewire]] in direct contact (hence solid pack) with a primary explosive, which is heated by electric current and causes the detonation of the primary explosive.  That primary explosive then detonates a larger charge of secondary explosive. Some solid pack fuses incorporate a small pyrotechnic delay element, up to a few hundred milliseconds, before the cap fires.

Match type blasting caps use an [[electric match]] (insulating sheet with electrodes on both sides, a thin bridgewire soldered across the sides, all dipped in ignition and output mixes) to initiate the primary explosive, rather than direct contact between the bridgewire and the primary explosive.  The match can be manufactured separately from the rest of the cap and only assembled at the end of the process. Match type caps are now the most common type found worldwide.

The [[exploding-bridgewire detonator]] was invented in the 1940s as part of the [[Manhattan Project]] to develop nuclear weapons.<ref>{{Cite web |last=Laboratory |first=Los Alamos National |title=Detonator Production {{!}} Organizations |url=https://organizations.lanl.gov/dp-division/past/ |access-date=2024-08-21 |website=Los Alamos National Laboratory |language=en}}</ref>  The design goal was to produce a detonator which functioned very rapidly and predictably).  Both Match and Solid Pack type electric caps take a few milliseconds to fire, as the bridgewire heats up and heats the explosive to the point of detonation.  Exploding bridgewire or '''EBW''' detonators use a higher voltage electric charge and a very thin bridgewire, .04 inch long, .0016 diameter, (1&nbsp;mm long, 0.04&nbsp;mm diameter).  Instead of heating up the explosive, the EBW detonator wire is heated so quickly by the high firing current that the wire actually vaporizes and explodes due to electric resistance heating.<ref>{{Cite report |url=https://www.osti.gov/biblio/1458273 |title=Physical and Electrical Measurements of Different Materials used in EBW Detonators. |last1=Valancius |first1=Cole Joseph |last2=Bainbridge |first2=Joe |date=2017-02-01 |publisher=Sandia National Lab. (SNL-NM), Albuquerque, NM (United States) |issue=SAND2017–1769C |language=English |last3=Richardson |first3=Duane Ross |last4=Love |first4=Cody Wade|osti=1458273 }}</ref>  That electrically-driven explosion causes the low-density initiating explosive (usually [[PETN]]) to detonate, which in turn detonates a higher density secondary explosive (typically RDX or HMX) in many EBW designs.<ref>{{Cite web |title=EBW Detonators |url=https://www.teledynedefenseelectronics.com/energetics/products/Pages/EBW%20Detonators.aspx |access-date=2024-08-21 |website=www.teledynedefenseelectronics.com}}</ref> In addition to firing very quickly when properly initiated, EBW detonators are much safer than blasting caps from stray static electricity and other electric current.  Enough current will melt the bridgewire, but it cannot detonate the initiator explosive without the full high-voltage high-current charge passing through the bridgewire.  EBW detonators are used in many civilian applications where radio signals, static electricity, or other electrical hazards might cause accidents with conventional electric detonators.


Exploding foil initiators (EFI), also known as [[Slapper detonator]]s are an improvement on EBW detonators.<ref name=":0">{{Cite report |url=https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/UCRL77639.xhtml |title=New Kind of Detonator: The Slapper. |last=Stroud |first=J. R. |date=1976 |publisher=California Univ., Livermore. Lawrence Livermore Lab.; Energy Research and Development Administration. |issue=UCRL77639}}</ref><ref>{{Cite journal |last1=Yang |first1=Zhi |last2=Zhu |first2=Peng |last3=Chu |first3=Qing-yun |last4=Zhang |first4=Qiu |last5=Wang |first5=Ke |last6=Jian |first6=Hao-tian |last7=Shen |first7=Rui-qi |date=2022-08-01 |title=A micro-chip exploding foil initiator based on printed circuit board technology |journal=Defence Technology |volume=18 |issue=8 |pages=1435–1444 |doi=10.1016/j.dt.2021.06.008 |issn=2214-9147|doi-access=free }}</ref>  Slappers, instead of directly using the exploding foil to detonate the initiator explosive, use the electrical vaporization of the foil to drive a small circle of insulating material such as [[PET film (biaxially oriented)|PET film]] or [[kapton]] down a circular hole in an additional disc of insulating material.  At the far end of that hole is a pellet of high-density secondary explosive.<ref name=":1">{{Cite journal |last1=Rae |first1=P. J. |last2=Dickson |first2=P. M. |date=July 2019 |title=A review of the mechanism by which exploding bridge-wire detonators function |journal= Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences|volume=475 |issue=2227 |pages=20190120 |doi=10.1098/rspa.2019.0120 |issn=1364-5021 |pmc=6694310 |pmid=31423094|bibcode=2019RSPSA.47590120R }}</ref> Slapper detonators omit the low-density initiating explosive used in EBW designs and  they require much greater energy density than EBW detonators to function, making them inherently safer.<ref name=":0" />

Laser initiation of explosives, propellants or pyrotechnics has been attempted in three different ways, (1) direct interaction with the HE or Direct Optical Initiation (DOI); (2) rapid heating of a thin film in contact with a HE; and (3) ablating a thin metal foil to produce a high velocity flyer plate that impacts the HE (laser flyer).<ref name=":1" /><ref>{{Cite web |last1=Yong |first1=Leo de |last2=Nguyen |first2=Tam |last3=Waschl |first3=John |date=May 1995 |title=Laser Ignition of Explosives, Pyrotechnics and Propellants: A Review |url=https://apps.dtic.mil/sti/pdfs/ADA299465.pdf |website=Defense Technical Information Center |publisher=Defense Science and Technology Organisation (DSTO)}}</ref>

== See also ==
* {{annotated link|Exploding-bridgewire detonator}}
* {{annotated link|Explosive booster}}
* {{annotated link|TM 31-210 Improvised Munitions Handbook}}
* {{annotated link|Triggering sequence}}

==References==
{{Reflist}}

==Further reading==
* Cooper, Paul W. ''Explosives Engineering''. New York: Wiley-VCH, 1996.  {{ISBN|0-471-18636-8}}.

== External links ==
{{Commons category|Detonators}}
* [https://archive.org/movies/details-db.php?collection=prelinger&collectionid=blasting_cap_danger 1956 safety film "Blasting Cap - Danger!"] from [[Prelinger Archives]]
* [https://www.scribd.com/doc/102732391/Modelling-and-Simulation-of-Burst-Phenomenon-in-Electrically-Exploded-Foils Modelling and Simulation of Burst Phenomenon in Electrically Exploded Foils] {{Webarchive|url=https://web.archive.org/web/20160424162530/https://www.scribd.com/doc/102732391/Modelling-and-Simulation-of-Burst-Phenomenon-in-Electrically-Exploded-Foils |date=2016-04-24 }}

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[[Category:Detonators| ]]
[[Category:Bombs]]
[[Category:Explosives]]
[[Category:Pyrotechnic initiators]]