CFAST Modelling Software Utilizing - Essay Example

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These locations or areas are located in a built environment which includes compartments that in turn divide the building structure into enclosed areas. A compartment within the built environment includes basic movement of air inside and outside the compartment and this flow of air is facilitated by shafts, vents, doors or windows (Hasofer, 2007). Within the discipline of fire dynamics, compartment fires reflect fires which take place in an enclosure area that has no openings, one opening or more than one opening (Drysdale, 1999). In the field of fire dynamics, a compartment is supposed to contain the fires occurring inside.

Basic differences exist between compartment fires and fires that take place in an open environment. The radiated heat produced by an open environment’s fire is lost in the surrounding atmosphere whereas this heat once produced in an enclosure is enclosed engendering critical impacts on the structural and the space characteristics of the compartment (Hasofer, 2007). CIBSE (2010) further explain this phenomenon which occurs within compartments by highlighting the fact that through the process of radiation, there is a translation of heat toward the compartment walls. In addition, walls are also impacted by the convection process which generates hot gases. The compartment related radiated hot boundaries heat contributes to the combustion heating rate and as such to the fire growth (CIBSE, 2010).

As shown in Figure 1, four fundamental stages characterize compartment fires and these include:
- Incipient stage,
- Growth stage,
- Fully developed fire stage,
- Decay stage (NIST, 2005).

The transition that occurs between the growth and the fully developed stage includes a crucial phenomenon known as flashover (NIST, 2005).

The above development curve just provides a general overview and as such cannot be generalised for all kinds of compartment fires and this is justified by the fact that the fuel specificities, oxygen availability and the available ventilation are crucial for determining the fire development speed (NIST, 2005). Other factors include also as indicated in Figure 3, the heat released rate and the duration of the burning process (NIST, 2005).

Various factors determine the indicators of fire behaviour which include either static or dynamic factors (Drysdale, 1998). Static factors include the specificities of building construction and dynamic factors include smoke characteristics and flames and have the potential to change with the development of fire (Drysdale, 1998). These indicators are further explained as follows:

Building structure: The building is static and its related structure, components and contents are stable with or without the occurrence of fire and ignition. This facilitates fire engineers' examination and analysis of these contents to find out the nature of fire behaviour and its impact (Hartin, 2005).

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