ABSTRACT
It should be understood that, although the fuels may exist in three different states, they can only be volatilized and consumed in the vapor state. Wood does not burn; the vapor coming off of the wood does. The burning of solid and liquid fuels takes place at the surface of the fuel in the area where the vapors have been created by heat and subsequently ignited. An oxidizing agent is required to support combustion. The most common is the oxygen in the Earth’s atmosphere. Normal atmospheric air contains 21% oxygen. Typically, flaming combustion occurs above 15% oxygen in the atmosphere. A smoldering fire may continue at much lower percentages. Generally, the higher the ambient temperature, the less oxygen is required for combustion.
