Firewalls are built between or through buildings, structures, or electrical substation transformers, or within an aircraft or vehicle.
Firewalls can be used to separate-high value transformers at an electrical substation in the event of a mineral oil tank rupture and ignition.
Knowing the potential conditions that may exist during a fire are critical to selecting and installing an effective firewall.
For example, a firewall designed to meet National Fire Protection Agency, (NFPA), 221-09 section A.5.7 which indicates an average temperature of 800 °F (425 °C), is not designed to withstand higher temperatures such as would be present in higher challenge fires, and as a result would fail to function for the expected duration of the listed wall rating.
Laboratory testing is used to simulate fire scenarios and wall loading conditions.