Robert G. Zalosh

External pressures generated by vented gas and dust explosions

Abstract Several different data correlations have been developed for the external pressures associated with vented gas explosions and dust explosions. These correlations, which are applicable to external locations in the direct line-of-sight of the enclosure vent, are reviewed here. In addition, the application of spherically symmetric and of ellipsoidal blast wave models is explored as a possible means of calculating external pressures over a wider range of conditions than is possible with the existing data correlations. Results indicate that the spherically symmetric blast wave model can obtain a comparable accuracy (8–9 kPa standard deviation) for line-of-sight locations as the more recent data correlations. In the case of the lower blast pressures at locations perpendicular to the vent line-of-sight, the ellipsoidal blast wave provides significantly better agreement with data (to within 1 kPa standard deviation for the one set of available test data) than the spherically symmetric model.

Hydrogen fuel tank fire exposure burst test

A fire exposure test was conducted on a 72.4 liter composite (Type HGV-4) hydrogen fuel tank at an initial hydrogen pressure of 34.3 MPa (ca 5000 psi). No Pressure Relief Device was installed on the tank to ensure catastrophic failure for analysis. The cylinder ruptured at 35.7 MPa after a 370 kW fire exposure for 6 min 27 seconds. Blast wave pressures measured along a line perpendicular to the cylinder axis were 18% to 25% less the values calculated from ideal blast wave correlations using a blast energy of 13.4 MJ, which is based on the ideal gas internal energy at the 35.7 MPa burst pressure. The resulting hydrogen fireball maximum diameter of 7.7 m is about 19% less than the value predicted from existing correlations using the 1.64 kg hydrogen mass in the tank.