Minimum ignition energy MIE or Emin
Definition
Lowest electrical energy stored in a capacitor, which upon discharge is sufficient to ignite the most ignitable mixture of dust and air, under specified test conditions.
Determination
The minimum ignition energy can be determined as well in the modified Hartmann tube as in the 20 l sphere or in the 1 m3 vessel with use of a suitable capacitor discharge device.
The results are usually indicated as a pair of varieties in the logarithmic graduation. The lower value refers to the energy which caused no reaction according to the specified process. The higher value refers to the lowest used energy which led to ignition.
Remarks
If only an individual value is indicated, the addition "<" means that the dust might ignite if the indicated energy is sparked. If ignition was not possible with the indicated energy, ">" appears.
Values for the minimum ignition energy determined with no inductivity in the discharge circuit are given with the remark "n.ind.".
Minimum ignition energy values exceeding 105 mJ come from tests in closed test apparatus according to the procedure described for the determination of pmax and KSt but using chemical igniters producing the ignition energy.
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