Aspect Ratio Effects in Unvented and Vented Dust Explosions
2012
Tamanini, F.
The sizing of vents for explosion protection of equipment and buildings depends on many characteristics of the system, including details of the geometry of the protected enclosure. Its aspect ratio (H/D) has been recognized as an important parameter, with the general result that volumes of greater H/D require larger vent areas. Published data on dust explosions in elongated enclosures have been used to develop a new correlation for this effect. The data are for two dusts, cornstarch and wheat flour, and were obtained from tests in volumes of 1, 9.4, and 20 m³, for a range of aspect ratios. The experimental results, which have been analyzed using modeling techniques developed at FM Global, have yielded a correlation that is validated against more than 200 points and includes the effect of the location of the ignition source. Comparisons with the formulas recommended in VDI 3673 (2002) (also EN 14491, 2006) and NFPA 68 (2007) have shown these alternative methods to yield predictions that either overpredict (VDI and EN) or are in general agreement (NFPA) with those from the present correlation.
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