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The '''minimum ignition energy''' ('''MIE''') is a safety characteristic in [[Explosion protection|explosion protection and prevention]] which determines the ignition capability of fuel-air mixtures, where the fuel may be combustible vapor, gas or dust. It is defined as the minimum electrical energy stored in a capacitor, which, when discharged, is sufficient to ignite the most ignitable mixture of fuel and air under specified test conditions.<ref>{{Cite web|url=https://staubex.ifa.dguv.de/HTML-Dokumente/ERLT8E.HTM|title=Minimum ignition energy MIE or E_min|access-date=2021-08-15|archive-url=https://web.archive.org/web/20190902120011/https://staubex.ifa.dguv.de/HTML-Dokumente/ERLT8E.HTM|archive-date=2019-09-02}}</ref> The MIE is one of the assessment criteria for the effectiveness of ignition, e.g. the discharge of electrostatic energy, mechanical ignition sources or electromagnetic radiation. It is an important parameter for the design of the protective measure of "avoidance of effective ignition sources".<ref>{{Cite web|url=https://downloadcenter.bgrci.de/resource/downloadcenter/downloads/R003_Gesamtdokument.pdf|title=Sicherheitstechnische Kenngrößen Ermitteln und bewerten|archive-url=https://web.archive.org/web/20210815123308/https://downloadcenter.bgrci.de/resource/downloadcenter/downloads/R003_Gesamtdokument.pdf|publisher=Berufsgenossesnschaft Rohstoffe und chemische Energie|archive-date=2021-08-15}}</ref> |
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'''Minimum ignition energy (MIE)''' is the minimum amount of energy required to ignite a combustible vapor, gas or dust cloud, for example by means of an [[electrostatic discharge]]. Ignition of a fuel/air mixture is possible only when the rate of liberation of heat near the ignition zone is greater than the heat loss by conduction. Heat loss due to radiation is not considered, as it is assumed to be negligible, and the ignition process is assumed to be steady and one-dimensional{{clarifyme|date=December 2012}}. MIE is measured in [[joules]] (J).<ref>Pratt, Thomas H. "Electrostatic Ignitions of Fires and Explosions" Wiley-AIChE (July 15, 1997) Center for Chemical Process Safety</ref> |
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[[Explosive]]s, [[hydrogen]], [[unsaturated hydrocarbon]]s and [[alkane]]s in oxygen have the lowest MIE: in the range of 1 to 100 μJ. Alkanes in air, distillate fuels, hybrid mixtures and extremely sensitive dusts have a MIE range of 0.1 to 10 mJ. Combustible dusts have a MIE range of 0.01 to 10 J. |
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For most materials the [[stoichiometric]] concentration can be calculated from the carbon and hydrogen content and is typically about twice the [[lower flammable limit]] (LFL). The lowest ignition energy value rarely occurs at the [[stoichiometric]] combustion concentration. For heavier gasses, the minimum usually occurs slightly above stoichiometric concentration and for lighter gasses such as Hydrogen, slightly below.<ref>{{cite book|last1=Magison|first1=Ernest C.|title=Electrical instruments in hazardous locations|date=1998|publisher=ISA|location=Research Triangle Park, NC|isbn=978-0979234316|edition=4th}}</ref> |
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== See also == |
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* [[Hydrogen safety]] |
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* [[Dust explosion]] |
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* [[Spark plug]] |
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==References== |
==References== |
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<references/> |
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==External links== |
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* [http://www.powderprocess.net/Safety_ATEX.html Explanations of MIE for powders (dust explosions) - powderprocess.net] |
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[[Category:Combustion]] |
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[[Category:Safety]] |
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Latest revision as of 17:44, 26 December 2023
The minimum ignition energy (MIE) is a safety characteristic in explosion protection and prevention which determines the ignition capability of fuel-air mixtures, where the fuel may be combustible vapor, gas or dust. It is defined as the minimum electrical energy stored in a capacitor, which, when discharged, is sufficient to ignite the most ignitable mixture of fuel and air under specified test conditions.[1] The MIE is one of the assessment criteria for the effectiveness of ignition, e.g. the discharge of electrostatic energy, mechanical ignition sources or electromagnetic radiation. It is an important parameter for the design of the protective measure of "avoidance of effective ignition sources".[2]
References
[edit]- ^ "Minimum ignition energy MIE or E_min". Archived from the original on 2019-09-02. Retrieved 2021-08-15.
- ^ "Sicherheitstechnische Kenngrößen Ermitteln und bewerten" (PDF). Berufsgenossesnschaft Rohstoffe und chemische Energie. Archived from the original (PDF) on 2021-08-15.
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