Determining TNT Equivalency for Confined Detonations

Abstract

Explosive containment vessels are typically designed and rated to contain a specified amount of trinitrotoluene (TNT) explosive charge weight. However, in application, these units typically contain explosive materials other than TNT. Additionally, proof testing of explosive containment chambers with TNT explosive is rare due to the availability of TNT commercially. Therefore, it is desirable to determine the capacity of an explosive containment vessel using an equivalent charge weight with respect to the TNT capacity of the vessel. Traditional wisdom suggests detonation chambers with large charge to volume ratios respond primarily in an impulsive manner. This assumption suggests that the impulse factor only should be used to determine the equivalent charge weight. However, it is also recognized that TNT equivalence with respect to confined detonations is not well understood and using standard methods for establishing TNT equivalency factors may not be adequate for confined detonations. This paper will investigate this common problem of determining equivalent charge weights for a containment vessel. This is accomplished using hydrocode modeling, finite element analysis and experimental test results.