The Effect of PETN Particle Size and Choice of EFI Technology on Detonator Performance Thresholds

Exploding Foil Initiators (EFIs) can be one of two types: a flexible foil or a chip. As the name suggests flexible foils are not rigid but comprise alternating layers of a metal conductor and an insulator. Whereas a chip EFI has the conducting metal layers and insulating flyer deposited onto a hard, ceramic substrate. It has commonly been suggested that chip EFIs are more efficient than an equivalent flexible foil EFI, however there appears to have been limited direct comparisons published. The relationship between surface area or particle size on and EBW detonator performance has been widely published but the effect on EFI performance less so. Therefore, a four-way threshold test has been performed to quantify the effects of both technology type and PETN particle. The results (threshold voltages and standard deviations) are reported for high and low surface area, detonator-grade PETNs with both flexible foils and chips. Powder compaction mechanisms are also discussed.

UK Ministry of Defence © Crown owned copyright 2023/AWE