Minimum ignition energy
The minimum ignition energy (MIE ) is a safety parameter for assessing the ignition of explosive atmospheres. Describes the lowest energy, which is sufficient for a discharge in order to ignite an explosive fuel -air mixture is ignitable in its composition. As fuel, combustible gases and vapors, as well as whirling dust come into question. Here, the minimum ignition of gases / vapors and dusts are fundamentally different. While gases and vapors can be ignited by ignition energies below 1 mJ usually ignition energies are necessary for typical dust in millijoule to joules range. For gases and vapors, virtually any source of ignition to be considered effective. For whirling dust the minimum ignition energy is an important parameter for the system design, as in the sense of the protection concept of avoidance of ignition sources, a consideration of the probability of occurrence of various energy ignition source and the ignition capability is possible.
Combustible dusts - dust explosion
The minimum depends strongly on the nature of dust such as of the composition, the particle size distribution of the surface structure and the moisture from. In general, with decreasing grain size and decreasing humidity decreases the minimum ignition. According to their minimum ignition dusts are in the areas of minimum
- MIE > 10 mJ cap sensitive than normal
- 10 mJ > MIE > 3 mJ particularly cap sensitive
- MIE <3 mJ extremely cap sensitive
Classified.
Flammable gases and vapors
The minimum ignition of gases and vapors are usually one to two orders of magnitude lower than that of dusts. Its value is concentration-dependent. Between the explosion limits of a parabola about the course is observed which corresponds to the most ignitable mixture mimimum with the lowest minimum ignition. The following tables are the minimum ignition important solvents and gases.
The value of the minimum decreases with increasing temperature, increasing pressure and increased oxygen content.