Dust Explosion Venting in Silos: a Comparison of Standards NFPA 68 and EN 14491

Venting devices are commonly used to try to reduce the damage caused by any dust explosion that may occur in silo systems. In North America and Europe the sizing of these vent areas is governed by standards NFPA 68 and EN 14491 respectively, both of which have recently come into force. The aim of the present work was to compare these standards in terms of the cost of protecting against dust explosions. Vent areas calculated according to NFPA 68 were smaller than those calculated in line with EN14491, except when the silos had a length/diameter ratio of 1, when the opposite was true. The difference increases for high length/diameter ratios, especially when the reduced explosion pressure is low. The optimum design for attaining minimum protection costs according to the two standards was slightly different. As a practical example, the cost of protecting a real silo using venting panels was calculated using both standards.