Explosives and Effects of Explosion Study Notes

Explosive: Any chemical compound, mixture, or device primarily designed to function through explosion.
Explosion: The sudden release of gases from a central point, accompanied by high temperature, intense shock waves, and loud noise.
Explosion Triangle: Requires the simultaneous presence of an Explosive atmosphere, Source of ignition, and Oxygen.
Combustion Nature: * Ordinary Combustion: Slow combustion. * Explosion: Rapid combustion. * Detonation: Instantaneous combustion.

Mechanical Explosion: Primarily a mechanical process involving the buildup of internal pressure surpassing the container strength (e.g., steam boiler, pressure cooker).
Chemical Explosion: Rapid, self-propagating transformation of chemically unstable material into stable substances, liberating heat and forming gases (e.g., all manufactured explosives).
Atomic/Nuclear Explosion: Energy release through Fission (splitting nuclei) or Fusion (joining nuclei).
Dust Explosion: Rapid combustion of fine particles (< 500 micron) suspended in an enclosed location. Requires the Dust Explosion Pentagon: Fuel, Heat, Oxidizer, Dispersion, and Confinement.
Gas Explosion: Result of a gas leak or decomposition of combustible gases mixed with air in the presence of an ignition source.

Incendiary/Thermal Effect: Generation of flames and intense heat; low explosives produce longer-lasting effects, while high explosives generate higher temperatures (bright flash).
Fragmentation Effect: Projection of debris at high velocity. If a casing is grooved via Serration or Pre-engraving, fragments have uniform size and shape. Shrapnel refers to added objects like nails or ball bearings.
Blast Pressure Effect: Instantaneous increase in air pressure (up to $700 ext{ tons/sq inch}$ ) traveling at high velocities (up to $17,000 ext{ miles per hour}$ ). * Positive Pressure Phase: Initial outward push of expanding gases; the most destructive force. * Negative/Suction Phase: Follows the positive phase and lasts $3$ times longer; creates a vacuum that pulls air and debris back toward the origin.

Shielding: Protection provided by an immovable object, though the blast wave continues with reduced force beyond it.
Reflection: The blast front encounters an object and changes direction, potentially amplifying damage in urban layouts.
Seismic/Water Effects: Shock waves can be transmitted through ground soil or water; water transmits waves with limited reduction in strength over distance.
Venting: The ability of gases to escape, which affects pressure buildup.

Primary: Damage from direct blast energy (e.g., ear drum rupture, Blast lung, brain injury).
Secondary: Injuries from projectiles, fragmentation, and debris.
Tertiary: Inertial injuries from victims being propelled by the blast.
Quaternary: Injuries from burns, asphyxiation, and toxic substances.
Quinary: Injuries from radiation, chemical burns, or infection.

Overpressure: The instantaneous rise in ambient pressure, expressed in PSI (Pound Per Square Inch).
Types: Incident, Reflective, and Peak overpressure.
Estimated Effects ( $1/2 ext{ kg TNT}$ ): * $3.4 ext{ PSI}$ at $5.5 ext{ metres}$ : Ear drum rupture. * $14.7 ext{ PSI}$ at $2.4 ext{ metres}$ : Minor head injuries. * $40 ext{ PSI}$ at $1.5 ext{ metres}$ : Lung damage (critical to terminal). * $80 ext{ PSI}$ at $1.15 ext{ metres}$ : Severe lung damage. * $220 ext{ PSI}$ at $0.9 ext{ metres}$ : Death.

DIPOLE MIGHT 23 (19 November 1997): Detonated $20,000 ext{ lbs C-4}$ in a van.
Tsar Bomba: Cloud reached $42 ext{ miles}$ tall and $60 ext{ miles}$ wide within ten minutes.
Putra Heights Pipeline Fire (1 April 2025): Petronas pipeline leak caused flames up to $30 ext{ metres}$ and a $32 ext{ ft}$ crater.