THE NATURE OF FIRE
Fire is due to a chemical process of oxidation, the combination of a substance with oxygen. Since fire is due to oxidation, it needs air to burn properly, and a flame will go out after it has used the available oxygen. Almost every material combines with oxygen given enough time. Iron, for example, will rust and the rust is oxidised iron. When the chemical combination occurs so rapidly that it is accompanied by a flame, it is called combustion.
The Ignition Point, or Kindling Temperature, is the degree of temperature at which a substance will catch fire and continue to burn. Substances, which can be ignited in the air, are called flammable.
The FlashPoint of a flammable item is lower than its ignition point. It is the temperature at which it gives off sufficient vapour to flash, or flame briefly, in air, but below the temperature at which it can burn continuously or spontaneously.
A fire, once started, will only be self-supporting when the temperature created by the combustion of the burning substance is as high as or higher than its ignition point. Some hard woods, such as ebony, require a great deal of heat to burn. If a stick of ebony is placed in a fire, it will burn. When it is removed the fire of the smouldering ebony itself has a lower temperature than the ignition point and the flames thus die. Fire can burn with or without flames. Flame indicates that heat has forced gas from a burning substance. The flame is produced by the combination of this gas with oxygen in the air.
Note: More detailed data on all of the topics covered in this document is published in the 200 + page User Manual which also includes hundreds of recipes and menu ideas as well as operating instructions and background data.
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