Minimum ignition energy is the minimum amount of energy required to ignite a combustible vapor, gas or dust cloud, for example due to an electrostatic discharge

Electrostatic discharge

Electrostatic discharge is a serious issue in solid state electronics, such as integrated circuits. Integrated circuits are made from semiconductor materials such as silicon and insulating materials such as silicon dioxide...

. MIE is measured in joules (J).

Explosives, hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, unsaturated hydrocarbon

Unsaturated hydrocarbon

Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. Those with at least one double bond are called alkenes and those with at least one triple bond are called alkynes...

s and alkane

Alkane

Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...

s in oxygen have the lowest MIE – range of to (mJ). Alkanes in air, distillate fuels, hybrid mixtures and extremely sensitive dusts have a MIE range of to (mJ). Combustible dusts have a MIE range of to (mJ).

For most materials, the lowest ignition energy value occurs at a concentration near the midpoint between those for the lower flammable limit

Lower flammable limit

Lower flammability limit , usually expressed in volume per cent, is the lower end of the concentration range of a flammable solvent at a given temperature and pressure for which air/vapor mixtures can ignite. The flammability range is delineated by the upper and lower flammability limit. Outside...

 (LFL) and the upper flammable limit (UFL).