Dust explosions in an experimental test silo: Influence of length/diameter ratio on vent area sizes

• Experimental test silo with different L/D ratio configurations.
• Vented explosion tests using maize starch and wheat flour.
• Results were compared to values proposed by EN 14491 and NFPA 68.
• Results suggest that L/D correction should be applied from L/D > 1.
• Standard EN 14491 seems to oversize vent areas in some cases.

Vented dust explosion tests have been conducted in an experimental test silo in order to analyse the effect of the length/diameter ratio (L/D). The modular design of the silo permitted the assembling of four different vessels with different geometries. The tests were carried out with wheat flour and maize starch, using three different vent area sizes. The silo was equipped with instrumentation which recorded the pressure generated by the explosion at various points in the silo, as well as the instant when the vent panel opened. The length/diameter ratio has been included in the empirical correlations currently employed in standards EN 14491 and NFPA 68 for calculating the size of vents. However, there are marked differences between the two standards when applied to certain situations, in part due to a different vent area correction for slenderness. The results obtained in this experimental test programme were compared with the standards, and indicated the advisability of applying an increase in vent area in elongated vessels when L/D > 1, as stated in EN 14491. However, this same standard appears to apply an excessively severe correction in some situations.

Figure optionsDownload as PowerPoint slide