Discussion Explosions and Explosives Explosions and Explosives An

Discussion Explosions and Explosives

Explosions and Explosives �An explosion is a chemical or mechanical action caused by combustion, accompanied by creation of heat and rapid expansion of gases. �The distinguishing characteristic of an explosion is the rapid rate of reaction. �The sudden buildup of expanding gas pressure at the origin of the explosion produces the violent physical disruption of the

Explosions and Explosives �Explosives are substances that undergo a rapid exothermic oxidation reaction, producing large quantities of gases. �This sudden buildup of gas pressure constitutes an explosion. �Detonation occurs so rapidly that oxygen in the air cannot participate in the reaction, so many explosives must have their own source of oxygen.

Explosions and Explosives �Detonation refers to the creation of a supersonic shock wave within the explosive charge. �This shock wave breaks the chemical bonds of the explosive charge, leading to the instantaneous buildup of heat and gases.

Low Explosives �Low Explosives decompose relatively slowly at rates up to 3000 ft/sec. � Examples include black powder, smokeless powder, and gas-air mixtures. �The only ingredients required for a low explosive is fuel and a good oxidizing agent.

High Explosives �High Explosives decompose very rapidly at rates from 3000 fps to over 25000 fps. � Examples include dynamite, TNT, PETN, and RDX. �There are two groups: primary and secondary.

Primary High Explosives �Primary High Explosives are very sensitive to heat, shock or friction, and normally detonate violently instead of burning. �They are used to detonate other explosives and are referred to as “primers. ”

Secondary High Explosives �Secondary High Explosives are relatively insensitive to heat, shock or friction, and normally burn rather than detonate in small quantities in open air. �These are the high explosives used in commercial and military blasting.