Testing of apparatus for determination of the minimum ignition energy of dusts

Status:

completed 07/1992

Aims:

In consideration of the particular practical relevance of the minimum ignition energy to the assessment of dust explosion hazards and to the selection of suitable measures for explosion prevention, the BG Institute for Occupational Safety (BIA) has put in place the conditions for routine determination of the minimum ignition energy of dust by the fabrication of test apparatus (Project 3027 "Installation of an apparatus for determination of the minimum ignition energy of dusts").

Activities/Methods:

Following adjustment and calibration in the test phase, the objective of this project was to assure, by performance of comparative tests, that within the measurement tolerances, consistent results are obtained both with the test apparatus employed by BIA (modified Hartmann apparatus, 20 l sphere) and in comparison with the results obtained by other test bodies.

Results:

Following adjustment and calibration, comparative tests employing lycopodium demonstrated successfully that, within the measurement tolerances, consistent results were obtained both with the test apparatus employed by BIA (modified Hartmann apparatus, 20 l sphere) and in comparison with results obtained by other test bodies (Ciba-Geigy, Dr. Pellmont Explosionsschutz). The comparative value for lycopodium of Emin >5 mJ/<15 mJ was also confirmed in the 20 l sphere (dust distributed by ring nozzle). Minimum ignition energies can thus now be measured routinely by the BIA in accordance with the test criteria laid down by the "Combustible Dusts" international working group in VDI Progress Report 134. Minimum ignition energy determinations were performed on 125 dusts in the test phase in the course of testing orders. The apparatus must be extended in order for the validity of results in the range Emin < 10 mJ to be enhanced.

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