Since the intensity of an explosion increases substantially on damming or as a result of turbulence-generating obstacles, gas or dust explosions in industrial plant can cause considrable damage. In connection with various research projects, medium and large-scale experimental studies on gas and dust explosions were undertaken in order to gain detailed information about the course and effects of explosions under realistic conditions and to assess possible means of improving safety precautions. Some typical experiments on expansion in dust explosions are presented on the basis of the measured explosive pressures and flame lenghts and compared with the calculated results obtained using the BASSIM CFD code developed by Battelle or by empirical modelling.