A dust is dust explosionable, if its mixture with air can be initiated by effect of an ignition source of defined energy to a keeping flame propagation. This is connected with a pressure increase in the closed container.
according to VDI 2263
(For more detailed informationen see also Fire and Explosion Protection)
Since an explosion can include both temperatures of more than 1000 °C and pressure increases on approximately 8 to 10 times of the initial pressure, a substantial danger potential is present.
Thus if a substance is combustible, an appropriate explosion prevention concept must be prepared.