L-262 TNT Equivalency of Energetic Materials: Review and Best Practices
When dealing with energetic materials, TNT equivalency is commonly used for different purposes. For scientific purposes, it is a means to compare the explosive effects delivered by different energetic compositions, by expressing them in terms of an equivalent TNT detonation. Therefore, we need a set of accurate TNT equivalence values for the effects we are considering and, if relevant, at different distances. For safety purposes on the other hand, we need conservative, but reasonable values, and if possible, standard ones for the various energetic materials and the munitions in which they occur.
paper first describes the most commonly used methods to determine TNT equivalences from a detonating charge: from theoretical methods to experimental ones including blast measurements. The available methodologies are presented and discussed. For cased charges, it is more difficult to determine TNT equivalences due to energy consumed by fragmentation and acceleration of fragments. This phenomenon depends on the confining material and its thickness.
In following sections, we present the results of a review on blast equivalency tests for propellants and pyrotechnics which are not designed to detonate. Specific test methods are identified that were derived from production or storage configurations. The TNT equivalency from these tests does not include effects from propulsively generated flying debris or thermal effects. Each situation should be evaluated with these effects in mind. Several best practices have been identified for both the experimental determination and empirical modelling of the TNT equivalency for explosives, propellants, and pyrotechnics. The main conclusion of this study is that there is currently no common agreement on the methods used to determine blast effects and, consequently, to determine TNT equivalency.