chemical reaction by which oxygen combineschemically with the burning material.Such things as rags or paper soaked with oil or withpaints or solvents are particularly subject tospontaneous combustion if they are stowed in confinedspaces where the heat caused by oxidation cannot bedissipated rapidly enough.A fire involving combustible fuel or other materialmust have an ignition source, and the material must behot enough to burn. The lowest temperature at which aflammable material gives off vapors that will burn whena flame or spark is applied is called the flash point. Thefire point, which is usually a few degrees higher than theflash point, is the temperature at which the fuel willcontinue to burn after it has been ignited. The ignition orself-ignition point is the lowest temperature to which amaterial must be heated to give off vapors that will burnwithout the aid of a spark or flame. In other words, theignition point is the temperature at which spontaneouscombustion occurs. The ignition point is usually at amuch higher temperature than the fire point.METHODS OF HEAT TRANSFERHeat from a fire is transferred by one or more of thefollowing methods:1. Conduction2. Convection3. RadiationConductionConduction is the transfer of heat through a body orfrom one body to another by direct physical contact. Forexample, on a hot stove, heat is conducted through thepot to its contents. Wood is ordinarily a poor conductorof heat, but metals are good conductors. Since mostships are constructed of metal, heat transfer byconduction is a potential hazard. Fire can move fromone fire zone to another, one deck to another, and onecompartment to another by heat conduction.Often, the skillful application of water, using fogpatterns to rapidly coat and recoat surfaces with a film ofwater, will slow or halt the transmission of heat byconduction. Fog patterns coat surfaces more efficiently12-20Student Notes:Figure 12-8.—Tetrahedron and fire triangle.
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