Blast effects of external explosions

Security considerations for industrial production and storage require characterization of the mechanical effects caused by blast waves resulting from a detonation or deflagration. This paper evaluates current analytical methods to determine the characteristic parameters of a blast wave with respect to the pressure, impulse and duration of the positive phase of the blast. In the case of a detonation, the trinitrotoluene (TNT) equivalent-based method determines the mass of TNT that is equivalent to the gas load used during the explosion and evaluates the characteristic parameters. A review of the energy values for TNT detonation is given, and the relationships used to calculate the TNT equivalent are proposed. The identification of the effects of the pressure wave following the explosion of a gaseous charge in free space equates the deflagration propagation to a piston. In the case of an explosion in an obstructed medium, the deflagration is considered to consist of a basic set of explosions involved in the generation of an intense blast wave. An explosion creates high pressures if the flame reaches high speeds, which occurs in the presence of turbulent flow at the source level or for a degree of confinement and obstruction in the medium.