TNT equivalency for overpressure and impulse for detonations of spherical charges of high explosives

Equivalency is often used to enable calculations of overpressures and impulses for explosives other than TNT. Equivalent mass factors are available for far-field detonations but none are available for near-field detonations. These reported factors are associated with incident overpressure and impulse and assumed appropriate for reflected overpressure and impulse. Numerical studies of TNT-equivalent mass factors for four high explosives (PETN, Composition B, Pentolite and Tetryl) for incident and normally reflected peak overpressure and scaled impulse are presented for a wide range of scaled distance 0.06 = Z = 40 m/kg^1/3. Emphasis is placed on near-field detonations for which no reliable factors are currently available.