All you want to know about explosives
What a high order explosive is and what a low order explosive is. Note that low order explosives can still create a substantial amount of energy, but it does not create the shock wave that a high order explosive would.
Low order explosives COULD conceivably be used in certain demo situations where the material isn't too hard or is porous, such as a mining company wishing to split or crumble rocks in order to reach a more valuable material inside or further in or down.
Hardened steel would require high order explosives.
Low-order explosives (LE) create a subsonic explosion [below 3,300 feet per second] and lack HE's over-pressurization wave. Examples of LE include pipe bombs, gunpowder, and most pure petroleum-based bombs such as Molotov cocktails or aircraft improvised as guided missiles.
A High Explosive (HE) is a compound or mixture which, when initiated, is capable of sustaining a detonation shockwave to produce a powerful blast effect. A detonation is the powerful explosive effect caused by the propagation of a high-speed shockwave through a high explosive compound or mixture. During the process of detonation, the high explosive is largely decomposed into hot, rapidly expanding gas.
The most important single property in rating an explosive is detonation velocity, which may be expressed for either confined or un-confined conditions. It is the speed at which the detonation wave travels through the explosive. Since explosives in boreholes are confined to some degree, the confined value is the more significant. Most manufacturers, however, measure the detonation velocity in an unconfined column of explosive 1- i/4 in. in diameter. The detonation velocity of an explosive is dependent on the density, ingredients, particle size, charge diameter, and degree of confinement. Decreased particle size, increased charge diameter, and increased confinement all tend to increase the detonation velocity. Unconfined velocities are generally 70 to 80 percent of confined velocities.
The confined detonation velocity of commercial explosives varies from 4,000 to 25,000 fps. With cartridge explosives the confined velocity is seldom attained. Some explosives and blasting agents are sensitive to diameter changes. As diameter is reduced, the velocity is reduced until at some critical diameter, propagation is no longer assured and misfires are likely.
Relative effectiveness factor (R.E. factor) is a measurement of an explosive's power for military demolitions purposes. It measures the detonating velocity relative to that of TNT, which has an R.E. factor of 1.00. TNT equivalent is a measure of the energy released from the detonation of a nuclear weapon, or from the explosion of a given quantity of fissionable material, in terms of the amount of TNT (trinitrotoluene) which could release the same amount of energy when exploded. The twelve-kiloton Hiroshima atomic bomb had had a blast effect alone equivalent to some twenty-five million pounds of TNT-that's million.