Minimum ignition energy (MIE) is defined as the electrical energy stored in a capacitor which, when released as a high voltage spark, is just sufficient to ignite a dust cloud at its most easily ignitable concentration in air.

A modified Hartmann-tube test apparatus made of glass or plexiglass with a volume of 1.2 liter is used as the explosion chamber. The dust sample is dispersed in the Hartmann tube by a pulse of compressed air and attempts are made to ignite it by an electric spark of known energy. Trials are made at different dust cloud concentrations and spark energy levels to establish the MIE value.

MIE test results are used primarily to assess the susceptibility of a dust cloud to ignition by electrostatic discharges (sparks).

The Minimum Ignition Energy test is performed in accordance with the requirements of the current edition of the American Society for Testing and Materials (ASTM) E2019.