The dangers of hazardous fires, such as pool- and tank fires in chem. plants are discussed. The importance and the role of fluid dynamics in the combustion processes are stressed. Exptl. methods used for the visualization of fires are described. The effect on safety of burning rate, max. pool fire diam., flame height and flame tilt, and total radiative power are discussed. The point source model and the solid flame radiation model are presented for calcn. of the distance-dependent radiation intensity from a pool fire. A new model, the parcel-radiation model, considers the radiation of hot spots, soot parcels, and the effect of radiation blockage by cooler, unburnt fuel parcels. Application of the parcel-radiation model leads to the calcd. max. irradn. E ~ 4 W/cm2, which is verified exptl. for most pool fires with diams. >14 m. These irradn. intensities are 3 times smaller than the values calcd. by the solid flame radiation model. The consequences of this model in detn. of safe distance between 2 adjacent pools are d3scussed.