Eckhoff (1995) emphasized that much published information on
ignitability and explosibility of metal dusts lack adequate information
about the particle size in the fine tail of the size distribution,
and, therefore, are of limited value. Particle size measurements at
least down to 1 mm should be regarded as an indispensable part of
future experimental investigations of ignitability and explosibility
of metal dusts.
Fig. 3 illustrates how the minimum explosive dust concentration
is influenced by particle size. The particles used in these experiments
were of narrow size distributions. In practice, the distributions
may be quite wide, and simple relationships for near monosized
dusts may not apply. Fig. 4 shows the very strong influence of
the particle size on the minimum electric spark ignition energy
(MIE) for three different dusts.