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Fire
Terms Fire: §
The process of combustion during which flammable materials
burn producing heat, accompanied by flames, smoke or toxic gasses, or any
combination of these. §
The common misconception is that fire burns the actual piece
of wood or fuel. It is the gasses given off by an object that actually burn. §
Heat causes objects to give off these flammable gasses, and
when the gasses reach their ignition temperature you see the light given off
during the oxidation process, known as fire. §
Fire itself generates more heat to the object and thus an
endless cycle begins until all of the gasses have been exhausted from an
object. Then the remaining particles or ash are what is left. Flammable: Capable of being
readily ignited and burning in air. Combustion: An exothermic
reaction of a substance with oxygen, causing the release of heat and generally
accompanied by flames, or glowing, and/or the emission of gasses or smoke. Combustible Material: Any material in a building or
structure that is combustible as determined by a Combustibility Test for
materials. Fire Hazard: The potential for any
item to give rise to a fire when exposed to an ignition source. Potential for injury and/or damage from fire Fire compartment Enclosed space,
which may be subdivided, separated from adjoining spaces within the building by
elements of construction having a specified fire resistance Fire exposure Extent to which
persons, animals or items are subjected to the conditions created by fire Fire resistance Ability of an item
to fulfil for a stated period of time the required stability and/or integrity
and/or thermal insulation, and/or other expected duty specified in a standard
fire-resistance test Flash-over Transition to a state of total surface
involvement in a fire of combustible materials within an
enclosure Fire Load: The heat energy potential of the
entire combustible contents of a building space, including furnishings, built
in and removable items, and partitions, floors and ceilings, normally expressed
as mega joules (MJ). Fire Load Density: The fire load divided by the
floor area, expressed in joules per square metre (J/m2). Fire Integrity: The ability of a constructed
element, when exposed to a fire on one side, to prevent the passage of flames
and hot gasses or the occurrence of flames on the unexposed side, for a stated
period of time determined in a standard fire resistance test. Fire Isolation: The isolation of one
part of a building by a fire resistant method of construction. A limit state of
collapse or loss of structural integrity due to fire. Fire safety; An essential part of any
building fire safety system (probably the most important part) is training and
education of the occupants in matters of fire safety. At its most basic, is based upon
the principle of keeping fuel sources and ignition sources separate. Fire Resistance: The ability of an element of
construction, component or structure to fulfil, for a stated period of time,
the required structural adequacy, integrity, thermal insulation or other expected
duty, during exposure to a standard fire resistance test. Exothermic and Endothermic An exothermic
process is one that gives off heat i.e. heat is transferred to the
surroundings. Many chemical reactions release energy in the form of heat,
light, or sound. Exothermic reactions may occur spontaneously and may even be
explosive. An endothermic
process is one in which heat has to be supplied to the system from the
surroundings. An endothermic reaction must absorb energy in order to proceed
and cannot occur spontaneously. Work must be done in order to get these
reactions to occur. When endothermic reactions absorb energy, a temperature
drop is measured during the reaction. A thermoneutral process is one
that neither requires heat from the surroundings nor gives off energy to the
surroundings. These terms are usually applied to chemical
reactions. A chemical reaction can only be one of these three terms at once. A
reaction that is exothermic will be endothermic if run backward and vice-versa.
Adiabatic A term used to describe a
combustion reaction in which all heat generated is retained in the products of
combustion. Adiabatic flame temperature is the theoretical temperature that
would be attained by the products of combustion provided the entire chemical
energy of the fuel, the sensible heat content of the fuel and combustion above
the datum temperature were transferred to the products of combustion. This
assumes that there is no heat loss to surroundings and no dissociation. Dissociation is a reaction involving the breakdown of chemical compounds.
In the case of combustion, these are water vapour and carbon dioxide. Stoichiometric describes the correct mixture of ingredients in a chemical reaction.
After the reaction is over, no surplus ingredients will be left. In combustion,
the stoichiometric ratio also is called correct,
ideal or perfect ratio. Pyrolysis That part of the irreversible chemical
decomposition caused solely by a rise in temperature. This decomposition can
provide a buffer between the burning surface and the material beneath Australian Fire Standards (Parts of AS
1530) AS 1530.1-1994 :
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