| Abstract: | A critical diameter exists for both high velocity (HVD) and low velocity detonation (LVD). No relationship exists between these two diameters, however they are both dependent upon the temperature, confinement, contaminants, type of detonation and, most importantly, geometry. In cylindrical geometry, the critical diameter is determined by go/no go tests which are relatively expensive and time consuming. In this respect, there is a need for a method by which the critical diameter can be determined quickly and reliably. A relatively simple procedure which can also be performed in the field is proposed in this article where the critical diameter is determined in principle by a single test through the application of conical geometry. However, on account of “overdrive”, the values always fall below those obtained by cylindrical geometry. Metal plating is proposed as a method of indication. The results are then compared simultaneously by optical and electrical measurements. The temperature dependence of the critical diameter of the HVD of pure nitromethane was also demonstrated by conical geometry and was compared to the values of cylindrical geometry. The method was originally proposed as a joint US/German effort between Dr. Mallory of NSWC, China Lake, and Dr. Leiber of BICT. Since Dr. Mallory has recently passed away, the question is therefore open as to whether or not this test can be approved internationally. |
