What are the primary properties that distinguish high explosives from low explosives?

High explosives and low explosives are two distinct categories of explosive materials, each with its own set of properties that differentiate them. Understanding these properties is crucial for certified explosive technicians to handle these materials safely and effectively.

1. Rate of Decomposition:
- High Explosives: High explosives decompose rapidly, producing a shock wave characterized by supersonic speeds. This rapid decomposition leads to the generation of high-pressure gases and a significant release of energy. High explosives are used in applications where a sudden release of energy is required, such as in military munitions and industrial blasting.
- Low Explosives: In contrast, low explosives burn comparatively slowly, releasing energy over a more extended period. They deflagrate rather than detonate, and their shock waves are subsonic. Low explosives find use in applications where a controlled and sustained release of energy is needed, such as in fireworks and propellants.

2. Shock Sensitivity:
- High Explosives: High explosives are typically more shock-sensitive than low explosives. They can be initiated by a shock or impact, making them suitable for military and demolition purposes. Their sensitivity to shock necessitates careful handling and transportation procedures.
- Low Explosives: Low explosives are less sensitive to shock and require a heat source, spark, or primer to initiate the combustion process. This characteristic makes them safer to handle and transport under normal conditions.

3. Chemical Composition:
- High Explosives: High explosives often have complex chemical compositions, with ingredients carefully engineered to achieve rapid and powerful detonations. Common examples include TNT (Trinitrotoluene) and RDX (Cyclotrimethylenetrinitramine).
- Low Explosives: Low explosives typically consist of simpler compounds, such as black powder (a mixture of sulfur, charcoal, and potassium nitrate). Their chemical composition allows for slower, controlled combustion.

4. Detonation Velocity:
- High Explosives: High explosives have a detonation velocity ranging from 1,000 to 9,000 meters per second (approximately 3,280 to 29,528 feet per second). This high velocity results in the shock wave associated with rapid, destructive explosions.
- Low Explosives: The detonation velocity of low explosives is significantly lower, typically in the range of 400 to 1,800 meters per second (approximately 1,312 to 5,906 feet per second). This slower velocity is characteristic of their deflagration process.

5. Applications:
- High Explosives: High explosives are used in applications where a sudden and powerful release of energy is required, such as in military ammunition, demolitions, and mining operations.
- Low Explosives: Low explosives are employed when a controlled burn with a slower release of energy is needed, as in fireworks, signal flares, and propellants for firearms and rockets.

In summary, the primary properties that distinguish high explosives from low explosives include their rate of decomposition, shock sensitivity, chemical composition, detonation velocity, and intended applications. Certified explosive technicians must be well-versed in these distinctions to ensure safe handling and use of these materials in various contexts.