Current vent sizing guidelines, developed both in Europe (VDI 3673) and in the United States (NFPA 68) for the protection of equipment and buildings from dust explosions, rely on statistical regressions of test data. This leads to limitations in the range of applicability of the design methods, and, in some cases, to questionable scaling of the results. Analysis of available experimental information with knowledge derived from models of vented explosions offers a suitable alternative which can overcome these problems. An effort based on this approach has produced significant improvements in several aspects of explosion vent sizing, including: vent duct and panel inertia effects, partial volume deflagrations, venting of equipment inside buildings, and explosions at initial elevated pressure. The output of this work has been incorporated in revised vent sizing guidelines which are used by Factory Mutual Engineering Association (FMEA) loss prevention consultants in the development of loss prevention recommendations for industrial and commercial properties. This paper discusses the development of the guidelines, with emphasis on the aspects in which they significantly differ from the guidance provided by other published methods.