Dynamite
Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay), and stabilizers.[1] It was invented by the Swedish chemist and engineer Alfred Nobel in Geesthacht, Northern Germany, and was patented in 1867. It rapidly gained wide-scale use as a more robust alternative to the traditional black powder explosives. It allows the use of nitroglycerine's favorable explosive properties while greatly reducing its risk of accidental detonation.
This article is about the high explosive. For other uses, see Dynamite (disambiguation).Manufacture[edit]
Form[edit]
Dynamite is usually sold in the form of cardboard cylinders about 200 mm (8 in) long and about 32 mm (1+1⁄4 in) in diameter, with a mass of about 190 grams (1⁄2 troy pound).[7] A stick of dynamite thus produced contains roughly 1 MJ (megajoule) of energy.[8] Other sizes also exist, rated by either portion (Quarter-Stick or Half-Stick) or by weight.
Dynamite is usually rated by "weight strength" (the amount of nitroglycerin it contains), usually from 20% to 60%. For example, 40% dynamite is composed of 40% nitroglycerin and 60% "dope" (the absorbent storage medium mixed with the stabilizer and any additives).
Storage considerations[edit]
The maximum shelf life of nitroglycerin-based dynamite is recommended as one year from the date of manufacture under good storage conditions.[7]
Over time, regardless of the sorbent used, sticks of dynamite will "weep" or "sweat" nitroglycerin, which can then pool in the bottom of the box or storage area. For that reason, explosive manuals recommend the regular up-ending of boxes of dynamite in storage. Crystals will form on the outside of the sticks, causing them to be even more sensitive to shock, friction, and temperature. Therefore, while the risk of an explosion without the use of a blasting cap is minimal for fresh dynamite, old dynamite is dangerous. Modern packaging helps eliminate this by placing the dynamite into sealed plastic bags and using wax-coated cardboard.
Dynamite is moderately sensitive to shock. Shock resistance tests are usually carried out with a drop-hammer: about 100 mg of explosive is placed on an anvil, upon which a weight of between 0.5 and 10 kg (1 and 22 lb) is dropped from different heights until detonation is achieved.[9] With a hammer of 2 kg, mercury fulminate detonates with a drop distance of 1 to 2 cm, nitroglycerin with 4 to 5 cm, dynamite with 15 to 30 cm, and ammoniacal explosives with 40 to 50 cm.