Explosive Theory

Question 1

Define an Explosion

Answer 1

Rapid transfer of heat through a layer or layers of material, which is characterised by heat, flash, sound and large quantities of gas (pressure).

Question 2

Three Types of Explosion

Answer 2

• Physical Explosion - Rapid transformation - Mechanical, BLEVE (Boiling Liquid Expanding vapour Explosion), Electrical (Arcs etc)
• Chemical Explosion - Rapid burning of substance or mixture.
• Atomic Explosion - Fission & Fusion

Question 3

Four Charachteristics of an Explosion

Answer 3

• Heat
• Pressure/Gas
• Light
• Sound

Question 4

Burn Rates (4)

Answer 4

• Low Explosive => 300 m/s (Gunpowder, propellants etc.) Easily initiated
• High Explosive - Primary => 3500-5000 m/s (Detonators) Extremely Sensitive
• High Explosive - Secondary - Primers/Boosters => TBC. Second stage in chain, sensitive to heat, shock & friction
• High Explosive - Secondary - Main Charge => 5500-9000 m/s (TNT, RDX ETC) Powerful, only detonates from primary, creates brisance.

Question 5

Define Combustion

Answer 5

An exothermic oxidation reaction producing flame, sparks and smoke. The oxidant may be part of the material as in a propellant, or oxygen from the atmosphere or other sources.

Question 6

What are the four explosive effects?

Answer 6

• Blast
• Earth Shock
• Fragmentation
• Fire/incendiary

Question 7

Types of shaped charge (3)

Answer 7

1. Munroe Effect (80 Deg)
2. Misznay-Schardin Effect (Concave plate)
3. Plate Charges

Question 8

What does the ‘falling block test’ measure?

Answer 8

Figure of Insensitivity (FOI)

Question 9

FOIs (3)

Answer 9

Primary Explosives - 0-50
Primers/Boosters - 50-100
Main Charge Fillings - 100+