Dust explosions are time-dependent flame propagation processes. Their description with "lumped parameter models" like the K-St value are of Limited validity only. More evidence of the process of flame propagation may be expected from an investigation of the flame velocity being composed by the laminar and turbulent velocities and the flow velocity. In the present paper the influences of the dust concentration and the flow velocity have been investigated by experiments in tube apparatus of three different diameters showing the dominating influence of the flow velocity and the turbulent rms velocity on the flame propagation. In addition, laminar and turbulent flame propagation has been investigated by an appropriate numerical model. Furthermore flow structures and particle distributions have been computed in a real size grain silo to assess the effects of possible explosions. (C) 2000 Elsevier Science Ltd. All rights reserved.