Introduction to Fire Safety Management

Figure 7.22
Example of fi re load from storage containers 
in a warehouse
Not only should the contents and activities be 
considered in relation to fi 
re growth, but also the 
arrangements for the storage, of materials with potential 
for high heat release.
Heat release from materials is measured in 
megawatts per square metre (MW/m
2
). Some mater ials 
generate much greater MW/m
2 
than others. For example, 
wooden pallets that are stacked 1.5 metres high are 
likely to release 5.2 
MW/m
2 
whereas polystyrene jars 
packed in cartons stacked at the same height have a 
heat release of 14 MW/m
2
.
Table 7.3 shows some examples of common 
commodities together with their known fi re loading in 
terms of megawatts per square metre. When consid-
ering the fi re risk associated with stored materials it is 
important to think about the heat that may be generated 
when materials are involved in a fi re.
It is also widely recognised that the containers within 
which some materials are stored add signifi cantly to the fi re 
loading within buildings, most notably bulk warehouses. 
The Hazardous Installations Directorate report on chemical 
warehouse hazards states that fl ammable liquids in plastic, 
intermediate bulk containers (IBCs) present a very high risk 
because they inevitably fail in the case of a fi re releasing 
their contents, adding, as a rule of thumb, around 3 MW/
m
2
to the total rate of heat release each.
As can be seen from the examples above and the 
issues discussed in both construction and ventila-
tion, fi re growth is not based on any one element but 
a combination of all. This will need to be taken into 
account when undertaking fi re risk assessments and any 
subsequent action plans.