6th December 2008Definition of fireFire can be defined as the rapid relentless chemical change that releases heat and light which comes with the accompaniment of flame, especially the exothermic oxidation of a combustible substance. As the chemical change takes place “fire” it grows in several stages. The incipient stage This is what may commonly be referred as the growth stage. This stage which can take a few minutes to happen and its characterized by fire growing, increasing in size from small flames to full fire that extends to the entire room.
The free-burning stageAlso the fully developed stage, this is when the fire is fully charged and the fire continues to burn until the available fuel and/or oxygen is consumed. The decay stageThis is the stage where the fire dies out and most flames that were visible diminish. As the available oxygen is consumed in the decay stage, the fire slowly gets to the decay stage. Pre-mixed flames and diffusion flames differ in that the flames follow opposite directions due to the different influences of temperature. As the temperature rises in pre-mixed flames the rate of oxidative attack on the soot precursors increases faster than the rate of precursor formation.
Thus the higher the temperature the less is the tendency to soot. What are the 5 functional requirements of Approved Document B? There are two broad standards for the design methods of fire resistance of buildings: prescriptive and performance-based. The difference between the two is that in the Performance-based design method of fire resistance in buildings starts with an analysis of fire scenarios to determine which design alternatives will meet those fire safety goals while the prescriptive design apply single fire scenario to evaluate all structural members and neglecting other fire factors. What are the two categories of fire testing?
Explain the difference between them. Fire testing is used as a means of determining if the fire protection products meet the minimum performance criteria as per the applicable legislation. There are two categories of fire testing; Carrying out more than one experiment on the same parameterIt is important to carry out more than one experiment to test the same parameter; this is always done in order to reduce the margin of error.
Fire within a compartment is influenced by ventilation receiving which helps it with the continued renewal of oxygen and helping in the expelling the smoke and fire gases. (NFPA 2007)How is heat transferred in a compartment fire? Include a diagram. Transfer of heat in a compartment fire the combustion consumes the oxygen while potentially flammable gases remain within the space accumulating from the ceiling downward. When the temperature inside this space reaches the ignition temperature of these gases and the oxygen's concentration is within the flammable range, a generalized ignition may well happen, enveloping the entire space in a sudden deflagration.
(NFPA 2007)Flammability limits Flammability limits, this is the proportion of combustible gases in a mixture, which limits this mixture is flammable. Limiting oxygen index