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Firewall residential construction, separating the building into two separate residential units, and fire areas
Example of a firewall used to inhibit the spread of a fire at an electrical substation

A firewall is a fire-resistant barrier used to prevent the spread of fire. Firewalls are built between or through buildings, structures, or electrical substation transformers, or within an aircraft or vehicle.

Applications

Firewalls can be used to subdivide a building into separate fire areas and are constructed in accordance with the locally applicable building codes. Firewalls are a portion of a building's passive fire protection systems.

Firewalls can be used to separate-high value transformers at an electrical substation in the event of a mineral oil tank rupture and ignition. The firewall serves as a fire containment wall between one oil-filled transformer and other neighboring transformers, building structures, and site equipment.

Types

A building under construction, showing the structurally independent cinderblock firewalls subdividing the building
Building 4 of the Waynesboro Outlet Village, showing a concrete firewall running through the building
Concrete firewalls still standing on Building 7 of the former Waynesboro Outlet Village, following a firefighter training exercise which intentionally burned the building

There are three main classifications of fire rated walls: fire walls, fire barriers, and fire partitions.

Fire barrier walls are typically continuous from an exterior wall to an exterior wall, or from a floor below to a floor or roof above, or from one fire barrier wall to another fire barrier wall, having a fire resistance rating equal to or greater than the required rating for the application. Fire barriers are continuous through concealed spaces (e.g., above a ceiling) to the floor deck or roof deck above the barrier. Fire partitions are not required to extend through concealed spaces if the construction assembly forming the bottom of the concealed space, such as the ceiling, has a fire resistance rating at least equal to or greater than the fire partition.[3]

Portions of structures that are subdivided by fire walls are permitted to be considered separate buildings, in that fire walls have sufficient structural stability to maintain the integrity of the wall in the event of the collapse of the building construction on either side of the wall.[5]

Characteristics

Materials

Firewalls between the old buildings in Ulan-Ude

Performance based design

Firewalls are used in varied applications that require specific design and performance specifications. 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.

Performance based design takes into account the potential conditions during a fire. Understanding thermal limitations of materials is essential to using the correct material for the application. Laboratory testing is used to simulate fire scenarios and wall loading conditions. The testing results in an assigned listing number for the fire-rated assembly that defines the expected fire resistance duration and wall structural integrity under the tested conditions. Designers may elect to specify a listed fire wall assembly or design a wall system that would require performance testing to certify the expected protections before use of the designed fire-rated wall system.

High-voltage transformer fire barriers

Main article: High-voltage transformer fire barriers

Fire barriers are used around large electrical transformers as firewalls. These barriers are used to isolate one transformer in case of fire or explosions, preventing fire propagation to neighboring transformers.

See also

Notes

  1. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2009 Edition, section 3.3.14.6, NFPA 850-10 Fire Protection fotric Generating Plants and High Voltage DC Converter Stations 2010 Edition section 5.1.4.3-4
  2. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2009 Edition, section 3.3.14.5
  3. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2006 Edition, section 3.3.12.7
  4. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2009 Edition, section 3.3.14.7, NFPA 850-10 Fire Protection for Electric Generating Plants and High Voltage DC Converter Stations 2010 Edition section 5.1.4.3-4
  5. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2006 Edition, section A3.3.12.6
  6. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2006 Edition, section 4.6
  7. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2006 Edition, section 4.2
  8. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2006 Edition, section 4.9
  9. ^ NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, 2006 Edition, section 4.8.3