Near field blast effects from BLEVE

Abstract

There is a need to have a better understanding of the near field blast and impulse from boiling liquid expanding vapour explosions. Emergency responders and response planners need to know the ground loading on a bridge if there is a tank truck BLEVE, or the loading on a building if a tank truck suffers a BLEVE near a high rise building.When a tank suffers a BLEVE the vessel opens fully to release the contained energy. The release is strongly directional since the tank wall does not move away instantaneously. The piston effect of the expanding vapour generates a shock at some distance away from the tank. This shock then propagates into the surroundings. Behind this shock is an additional blast wind caused by liquid flashing. This may also produce a shock. When the tank opens fully and is flattened on the ground this produces a large impulse load. Long range projectiles are also possible.Experiments have been conducted using 50 mm diameter tubes filled with water or propane. These tubes have been heated until failure to produce a BLEVE release. The tube failure mode and kinematics was representative of pressure vessel failures. The tube supports contained load cells to measure the ground force. Pencil blast gages were located close to tube to measure overpressures. High speed shadowgraph imaging was used to capture the formation and movement of the shocks.The results include detailed data on near field blast and ground loading effects from a boiling liquid expanding vapour explosion.