(53d) Uncertainty in the Determination of the Ignition Energy of Dusts below 10mJ

Authors: 
Gabel, D., Otto-von-Guericke-Universität
Krause, U., Otto-von-Guericke-Universität
The Minimal Ignition energy (MIE) of dust often is in a non-critical region above 10 mJ. Depending on the substance, the humidity and the particle size distribution there are dusts where it is known, that their MIE is below 3mJ. These occur in the pharmaceutical industry as pure dust and potentially also in the mixture of dusts. Practical experience with measurement of such dust show, that the results become unreliable. At very low energies the influence of the ignition system, the type and form of the electrodes as well as the electrode distance become crucial. For different standardized MIE apparatuses and different underlying ignition systems these influences are examined with different dusts.
In general is to doubt that reported fixed values below 3mJ are reproducible with different apparatuses. That is why a improve ignition system is developed allowing to measure reliable low ignition energies off dust and dust mixtures, as these mixtures are often processed in industry. This is also considered as an important first step to be able to measure the MIE of hybrid mixtures that are not covered by the existing systems.