L-132 TNT Equivalency: Misconceptions and Reality

TNT equivalency is used as a basis for several important government regulation issues that include limits imposed upon the size and location of explosive storage facilities, siting and construction of explosive manufacturing and test facilities, and the packaging and transportation of explosives. TNT equivalency is also used by scientists, engineers and analysts in engineering calculations involving air blast, cratering, structural response, and physiological effects.

In this report, information related to the air blast test, the sand crush test, the ballistic mortar test, the plate dent test and the Trauzl tests, tests used to determine the TNT equivalency is provided. Ways of determining the TNT equivalent from these tests and their limitations are reported.

The key factors influencing the TNT equivalency such as the distance from the explosion source, the munition or stack geometry, the casing thickness, the explosive confinement (i.e., containers, packaging, surrounding structure) and the mass are addressed. Examples using the air blast test are reported.

Finally, TNT equivalencies for 48 high explosives, 15 solid propellants and a large range of liquid propellants are provided.

To conclude, it is important to remember that one must be aware of the limits of practical TNT equivalency application. Indeed, TNT equivalency air blast calculations are based on similitude laws. This implies that comparisons can be made between charges of the same shape, confinement, initiation mode and configuration of interest because all these factors influence the created air blast and therefore their TNT equivalency.