Explosive Materials & Chemical Composition Flashcards

Which sensitivity test is used to measure an explosive's response to impact, and what does a lower value indicate?

Answer: Drop hammer test; a lower drop height value indicates greater sensitivity to impact

In the drop hammer (fall hammer) test, the height at which a weight causes 50% probability of initiation (H₅₀) is measured—lower H₅₀ means the explosive is more sensitive to impact.

What is the purpose of a 'doping agent' such as wax in the composition of pressed explosive charges?

Answer: To reduce sensitivity to friction and impact while maintaining detonability with proper initiation

Wax and similar phlegmatizing agents coat explosive crystal surfaces, reducing sensitivity to accidental initiation stimuli without preventing proper detonation when a strong initiator is used.

Emulsion explosives resist detonation in water primarily because of which design feature?

Answer: The oxidizer droplets are encapsulated in a continuous oil-wax matrix, preventing water from reaching them

In water-in-oil emulsion explosives, ammonium nitrate solution droplets are surrounded by a continuous hydrocarbon phase, physically preventing water ingress and dissolution of the oxidizer.

What is the significance of the 'critical diameter' of an explosive?

Answer: The minimum charge diameter below which a stable detonation cannot propagate and the reaction fails

Critical diameter is the minimum diameter at which a specific explosive can sustain a self-propagating detonation wave; below this diameter, the detonation quenches.

Which of the following best describes the term 'sympathetic detonation'?

Answer: Detonation of one charge caused by the shock wave from an adjacent detonating charge without direct contact

Sympathetic detonation occurs when the shock wave from one exploding charge is sufficient to initiate a nearby charge, requiring careful inter-hole spacing to prevent unplanned detonations.

Compared to TNT, which property makes RDX a preferred military explosive?

Answer: Higher detonation velocity and brisance per unit weight

RDX has a detonation velocity of approximately 8,750 m/s and higher brisance than TNT (~6,900 m/s), making it more effective for shaped charges and fragmentation warheads.

What is the primary hazard associated with the exudation of nitroglycerin from old or degraded dynamite?

Answer: Exuded NG forms highly sensitive crystals on the surface that can detonate from slight friction or shock

Liquid NG that has migrated to the cartridge surface can recrystallize, and these crystals are extremely sensitive to mechanical shock or friction, making old dynamite extremely dangerous to handle.