Abstract:
The combustion process, or burning, is in fact the rapid oxidation of millions of fuel molecules in the vapor form. Once there is sufficient oxygen and the fuel vapor molecules properly mix, an ignition source is typically needed for oxidation to be initiated. However, once oxidation is initiated, it is an exothermic process. If sufficient energy is released during the reaction to maintain the elevated temperature of surrounding oxygen and fuel molecules, and there are sufficient oxygen and vaporized fuel molecules available, then the oxidation process will continue. Oxidation is a chemical reaction between the molecules of a substance and the oxygen molecules in the surrounding atmosphere. There are many common examples of oxidation, including the rusting of iron, the tarnishing of silver, or the rotting of wood. What is known as fire is actually a chemical reaction involving the oxidation of the fuel molecules. However, the reaction occurs at a much faster rate and only under certain conditions (e.g., elevated temperatures, proper mixture, etc.). In addition, what is called burning or combustion is actually the continuous rapid oxidation of millions of fuel molecules. Recognizing that the fire or combustion process is actually a chemical reaction (involving the oxidation of the fuel molecules) is critical to understanding the basics of the fire phenomena. Electric shock may result from contact with live electrical circuits. It is not necessary to touch one of the conductors of a circuit to receive a shock. Any conducting material that is electrified through contact with a live circuit will suffice. Thus, firefighters are endangered in two ways: First, they may touch a live conductor or some other electrified object while groping about in the dark or in smoke. Second, a stream of water or foam can conduct electricity to firefighters from live electrical equipment. Moreover, when firefighters are standing in water, both the chances of electric shock and the severity of shocks are greatly increased.