A. Low Explosives
Are defined as an explosive mixture which under any condition cannot support a detonation wave.
Low explosives are also defined as a solid mixture of chemicals which burn in the absence of air, but which, when confined, can burn to deflagration.
1. Black Powder
Black Powder is the oldest known explosive, but the exact history is obscure. The first documented mention of saltpeter (potassium nitrate or "nitre", the basic ingredient of black powder, is to be found in the 13th century writings of the Arabian author Abd Allah. Even before then, however, the Chinese are thought to have used saltpeter, perhaps as early as the 10th century. Their early work with saltpeter appears to have been limited to fireworks and rockets.
The first black powder plant in America was started in 1675, near Boston. The first recorded use of the material in blasting was at a copper mine at Simsbury, Connecticut in 1773.
Black Powder reigned as the king of explosives for some 600 years. Production in 1860 was about 27 million pounds, peaked around the turn of the century with nearly 100 million pounds produced. Black Powder consumption in the U. S. peaked at 277 million pounds in 1917. Today, it is less than 100,000 pounds, primarily used in the powder of safety fuse and in fireworks.
Black Powder, burns progressively.
a. Uses - Sporting, Blasting, Fireworks, Fuse and Fuzing systems
Granulations: Have an effect on the rate of the reaction.
(2.) "A" Blasting: Potassium Nitrate based
(3.) "B" Blasting: Sodium Nitrate based
c. Commercial Fuse:
Safety Fuse, A flexible cord containing solid flammable material by which fire or flame is conveyed at a continuous and uniform rate from the point of ignition to the cut end. A fuse igniter is usually attached to that end. Safety fuse may be used without a detonator to ignite low explosives non-electrically.
Identification of safety fuse is completed by examining the central core filler material which is black powder. The core will be black or gray in color.
The burning rate for safety fuse varies. A section 3 feet long should be test burned and timed.
The burning rate of safety fuse will vary for the following reasons;
Age of the fuse.
Humidity during storage
Altitude, faster burning rates have been observed during underwater burns.
Safety fuse, differing from modeling fuse burns internally and does not completely burn.
Construction: Outer was impregnated coating, black powder core sheathed in jute and cotton yarns, followed by an asphalt coating. While the asphalt is still hot, it is covered with an extruded yarn countering and the wax impregnate.
2. Photoflash Powder
a. Uses - Fireworks, Incendiary, Military Munitions
b. Types - Only one, which varies to the formulation
c. Ignition - The most sensitive low explosive to heat - shock - friction - electrostatic discharge
d. Formulation: Approximately 100 formulations containing:
Pyrodex, a registered trademark is a Black Powder substitute manufactured by Hodgdon Powder Company, Shawnee Mission, Kansas. It is designated as a "smokeless propellant" as required by the US Department of Transportation.
a. Uses - Black Powder substitute
b. Types: As with other low explosives, changes in formulation or grain size varies the rate of reaction and also the amount of gases produced.
c. Ignition: Sensitive to heat - shock - friction - electrostatic discharge, but less than black powder
4. Smokeless Powder
The propellant which has exclusively been used for a long time in conventional military weapons is the smokeless (or, more accurately low-smoke) powder.
b. Types - Over 100 grades available in single, double, and triple base powders