Friday, August 2, 2019
Pyrotechnics :: essays research papers
PYROTECHNICS Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Pyrotechnics special effects are widely used in motion picture production to create all types of effects involving explosions, fires, light, smoke and sound concussions. The types of pyrotechnics materials used include flash powder, flash paper, gun cotton, black powder (gunpowder), smokeless powder, detonator explosives, and many more. They are used in bullet hits (squibs), blank cartridges, flash pots, fuses, mortars, smoke pots, sparkle pots, etc. The main problems of pyrotechnics include prematurely triggering the pyrotechnic effect, use of larger quantities or more dangerous materials than needed, causing a fire, lack of adequate fire extinguishing capabilities, and, of course, inadequately trained and experienced pyrotechnics operators. As a result of these risks, all pyrotechnics special effects are regulated at the federal, state and local level. In general, all pyrotechnics are explosives, but not all explosives are pyrotechnics. Class A explosives (high explosives) are materials like dynamite and Primacord which may detonate even if unconfined. Pyrotechnic special effects materials are Class B explosives. They will burn, but not explode unless confined. Examples are black powder and pellet powder, safety fuses, igniters, igniter cord, fuse lighters, Class B special fireworks, and Class B composite solids propellants. Class C explosives are common fireworks. Note that short lengths of Primacord may be classified as Class C under certain conditions. Both Class B and C explosives are also called low explosives. All pyrotechnic materials and other explosives consist of an oxidizer (source of oxygen) and a reducer (fuel). Examples of oxidizers include potassium nitrate, strontium nitrate, potassium perchlorate and potassium chlorate. Examples of fuels include metals like magnesium and aluminum, sulfur, silicon dioxide, and organic fuels like charcoal, starch, resins, and chlorinated hydrocarbons. The choice of fuel and oxidizer determines the type of effect (flash, smoke, sound, etc.) its color, and its intensity. There are two basic types of pyrotechnic materials: single component and two component systems. Single component materials will either burn if ignited, or explode if ignited when enclosed, since the oxidizer and fuel are in the same mixture. Flash paper, for example, is a partially nitrated cellulose and contains both fuel and oxidizer internally. The traditional black powder has potassium nitrate as the oxidizer, and sulfur and charcoal as fuels. In two component or binary systems, the oxidizer and fuel are separate components which are transported and stored separately and only mixed when ready to use.
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