Sensitivity
Definition
How easily an explosive is set off by impact, friction, spark, heat or shock. Primary explosives are highly sensitive; secondary explosives need a detonator; tertiary explosives need a booster.
- Definition axis
- Ease of initiation by impact, friction, spark, heat, or shock
- Primary explosives
- Highly sensitive, initiate with minimal stimulus
- Secondary explosives
- Require a detonator to initiate
- Tertiary explosives
- Require a booster charge to initiate
- Forensic relevance
- Governs classification and safe handling at scenes
Common questions
Why does sensitivity classification matter at a bomb scene?+
Knowing whether a device likely used a sensitive primary explosive for initiation versus an insensitive secondary or tertiary main charge helps render-safe teams predict how the device might have been triggered and what handling precautions the remaining components need.
Does high sensitivity always mean high explosive power?+
No, the two properties are largely independent. Primary explosives like lead azide are extremely sensitive but produce relatively low energy, which is exactly why they are used only as small initiating charges rather than as the main destructive charge.
How is sensitivity actually measured in a lab?+
Standardised tests such as impact sensitivity (drop-hammer), friction sensitivity, and electrostatic discharge sensitivity apply a controlled, increasing stimulus and record the level at which initiation occurs, allowing explosives to be ranked and safely classified.
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...
- Detonator
- A small initiating charge of primary explosive (lead azide, lead styphnate, mercury fulminate or DDNP) that converts an electrical, mechanical or pyrotechnic...
- 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...
- 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...