During this era of Covid spending time at airports seems like a distant memory. Looking out those large windows onto the apron, which is where aircraft are parked, you can see several fire protection measures at work. The surface of the apron is sloped away from the building in case of a fuel spill, the building itself is constructed of a certain level of fire resistance and the aircraft loading walkway has a pressurization system for safe egress, but what about that window you are looking through? NFPA 415, Standard on Airport Terminal Buildings, Fueling Ramp Drainage, and Loading Walkways, contains requirements for the protection of occupants and property for airport terminals, including their large landscape windows.
Glass vs Glazing?
If you are looking in the standard one of the first things you might notice is that it doesn’t use the term ‘window’ or ‘glass’. Rather, the terms ‘opening’, and ‘glazing material’ are used. Glazing is used because most windows are not made from solely glass, they are usually made from a mixture of layers or laminated glass, fiberglass, acrylics, or other plastics and the term glazing material covers all of these. The term opening is used for much the same reason, it is more generic and can apply in more situations if the opening is technically not a window. For example, if the term window was used this wouldn’t cover the use of a door, which would present many of the same hazards being addressed in NFPA 415.
When do airport terminal openings need to be protected?
If there is an opening in a wall that is within 7 ft of the floor and potential fuel spill points are less than 100 ft horizontally then the window needs to be protected with an automatic water spray system in accordance with NFPA 15, Standard for Water Spray Fixed Systems for Fire Protection. There has been testing that has shown the radiant heat from a fuel spill fire can be expected to break glass windows 75 ft away and can potentially ignite combustible materials within the building. If the window is between the finished floor and 7 ft there is a greater potential for occupants to be injured and so that is the threshold for the application of this requirement.
How do I provide protection?
While NFPA 415 says to follow NFPA 15, additional guidance that is proposed for the 2022 edition of the standard explains the intent by adding that the user should follow the vessel exposure protection provisions of NFPA 15. This makes sense since we are providing the window with exposure protection from the fuel spill fire. Something to keep in mind when designing a system like this is that you can take water rundown into consideration, which allows you to increase the vertical spacing of your nozzles up to 12 ft. Another common question we get about design is whether protection is needed to be provided for the entire window or just the bottom 7 ft. A proposed change to the 2022 edition clarifies that it is the intent for the system to protect the entire opening.
For more information on the design of glazing assemblies, please see Annex C of NFPA 415 which goes further into detail about glazing materials and the dangers aviation facilities can pose. Check out this ‘In Compliance’ article which gives an overview of all fire protection features in an airport. Let us know if you have any experience with the fire protection of airport terminals or send us a picture of the next water spray system you find.
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