Detonator
Definition
A small initiating charge of primary explosive (lead azide, lead styphnate, mercury fulminate or DDNP) that converts an electrical, mechanical or pyrotechnic input into a shock pulse strong enough to set off a secondary main charge.
- Function
- Converts an input signal into a shock pulse that initiates a main charge
- Charge type
- Primary explosive
- Common compounds
- Lead azide, lead styphnate, mercury fulminate, DDNP
- Trigger types
- Electrical, mechanical or pyrotechnic
Common questions
Why can't a secondary explosive like TNT be set off directly by a flame or spark?+
Secondary explosives are formulated to be relatively insensitive so they are safe to handle and transport, and they need a strong shock wave rather than heat or a spark to detonate reliably, which is exactly what the small, sensitive primary charge in a detonator supplies.
What does recovered detonator debris tell investigators at a post-blast scene?+
Fragments of the detonator shell, wiring, or bridgewire can indicate whether the device was electric or non-electric, sometimes point to a manufacturer or model through construction details, and help distinguish a commercial or military detonator from an improvised initiator.
Related terms
- Brisance
- The shattering power of a detonating explosive, distinct from heave (bulk displacement). Measured by the Trauzl lead block test. High-brisance explosives (RDX,...
- Deflagration
- A subsonic combustion front propagating through an explosive by thermal conduction. Characteristic of low explosives such as black powder and smokeless powder;...
- Detonation
- A supersonic shock wave coupled to a chemical reaction front, propagating through a high explosive at velocities between approximately 4,500 and 9,100...
- Explosive
- A chemical or mixture that undergoes rapid exothermic decomposition releasing large volumes of gas and heat when triggered by heat, shock, friction...
- Oxygen Balance
- A percentage expressing the surplus or deficit of oxygen in an explosive molecule relative to stoichiometric complete oxidation of carbon to CO2...
- Sensitivity
- How easily an explosive is set off by impact, friction, spark, heat or shock. Primary explosives are highly sensitive; secondary explosives need...
- Velocity of Detonation (VoD)
- The speed at which the detonation wave propagates through an explosive, measured in metres per second. RDX: approximately 8,750 m/s; TNT: approximately...