Practice good housekeeping procedures, such asthe daily removal of trash from spaces.Practice safety precautions when working withflammable materials.Report all potential fire hazards.Keep firefighting equipment handy and in goodworking order.Ensure closures and fittings are workingproperly and report any discrepancies.FIRE TRIANGLEThe entire chemistry and physics of fire andburning, or combustion, can be simplified into arelationship between three components—fuel, heat(temperature), and oxygen (air). To have a fire in anycombustible substance, each one of these componentsmust be present to help each other. Picture thesecomponents in the form of a triangle, as shown in figure12-7.Look at figure 12-7. Here, you can see that if theoxygen reacts with the fuel, it creates heat, which causesa draft or some other condition that takes in moreoxygen and creates still more heat, and so on. Or theheat may cause more fuel to become available (such ascausing gasoline to boil into vapor), which then takesmore oxygen to burn and creates more heat, which thenproduces still more fuel, and so on. The burning reactioncan go in many different directions.The modern science of firefighting and fireextinguishment is based on the sides of the fire triangleand an uninhibited chain reaction of burning.Obviously, the firefighter can remove one or more of thecomponents to cause the burning to stop. The type offirefighting agent the firefighter has at hand determineswhich component or components of the triangle will beremoved.Another way the firefighter can stop the fire (and thecombustion) is to place a screen between any twocomponents of the triangle. If the fighter uses an agentas a temporary screen that breaks the triangle, the firegoes out. Obviously, the fire can quickly start up again ifthis method is used because each of the three necessarycomponents is still there waiting to start the fire againonce the screen is gone.FIRE TETRAHEDRONThe fire triangle describes the requirements forsurface glowing or smoldering, but it doesn’tcompletely describe flaming combustion requirements.A fourth requirement, an uninhibited chain reaction, isneeded for flames to exist. This is shown by the firetetrahedron (fig. 12-8). A tetrahedron is a solid figurewith four triangular faces. It is useful for illustrating theflaming combustion process because it provides for thechemical chain reaction requirement and each facetouches the other three sides. As described for the firetriangle, flaming combustion stops when one of the foursides of the fire tetrahedron is removed.SPONTANEOUS COMBUSTIONFire, also called burning or combustion, is a rapidchemical reaction that results in the release of energy inthe form of light and heat. Most spontaneouscombustion involves very rapid oxidation; that is, the12-19Student Notes:Figure 12-7.—Requirements for combustion.
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