ANFO
Definition
Ammonium nitrate fuel oil: 94% ammonium nitrate prills + 6% diesel fuel oil. Detonation velocity approximately 4,500-4,800 m/s. The most widely used commercial blasting agent worldwide; requires a booster for reliable initiation.
- Composition
- 94% ammonium nitrate, 6% fuel oil
- Detonation velocity
- Approx. 4,500-4,800 m/s
- Classification
- Commercial blasting agent
- Initiation requirement
- Booster charge needed
Common questions
Why can ANFO not be set off with just a blasting cap?+
ANFO has relatively low sensitivity to shock compared to primary or many secondary explosives, so a detonator alone usually cannot deliver enough energy to initiate it reliably. A booster of a more sensitive explosive is placed in contact with it to bridge that gap.
Why is fuel-oil ratio significant in post-blast residue analysis?+
The 94:6 ratio is close to the oxygen-balanced optimum for the mixture, and deviations from it affect both detonation efficiency and the residue signature left behind, which examiners use alongside prill morphology to characterise the device that was used.
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;...
- Deflagration-to-Detonation Transition (DDT)
- The acceleration of a deflagrating burn front to supersonic detonation velocity, triggered by confinement. Relevant to understanding how improvised devices using low...
- 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...
- Ion Chromatography (IC)
- An analytical technique that separates and quantifies anions and cations in solution. In post-blast residue analysis, IC detects nitrate, nitrite, ammonium, and...
- Primary Explosive
- A high explosive sensitive enough to detonate from friction, spark, percussion, or flame without confinement or a separate booster. Examples: mercury fulminate,...
- Secondary Explosive
- A high explosive insensitive to normal friction, spark, and percussion; requires a primary explosive shock or blasting cap to initiate detonation. Examples:...
- Tertiary Explosive (Blasting Agent)
- An ammonium nitrate-based explosive formulation requiring both a primary and a booster charge for reliable initiation. ANFO is the globally dominant blasting...
- TNT Equivalent
- A normalised measure of explosive energy output relative to trinitrotoluene (TNT equivalent = 1.0). Used to compare blast yields across different explosive...