The importance of aircraft hangar fire protection is substantial and can be a difficult subject to tackle. Aircraft hangars can be a challenging structure when it comes to fire safety as they are quite different than other buildings in construction, size, and use.
Hangars tend to be quite large and also very open, a combination that makes fire and smoke control unmanageable if not approached in the right manner. Additionally, aircraft hangar structures are not only expansive, but they also house extremely flammable, combustible materials like chemical additives and jet fuel. Add in the fact that large aircraft, scaffolding, and sizable equipment in hangars makes detecting and extinguishing fire even tougher. It’s easy to see just how vital fire and smoke protection systems are in addition to proper structural designs.
NFPA Categorizations for Aircraft Hangar Fire Protection
All buildings will need to adhere to certain safety codes for fire protection, and not surprisingly aircraft hangars have much stricter guidelines. Large, commercial hangars often have fire safety requirements on such a vast scale that specialist engineers are often used. A fire safety engineer should also be consulted.
The National Fire Protection Association (NFPA) has strict standards for aircraft hangars (NFPA 409). The NFPA 409 code standard has four different categories:
- Group 1 – Aircraft bay exceeds 40,000ft2 with a hangar door taller than 28′
- Group 2 – Aircraft bay between 12,000ft2 and 40,000ft2 with a door shorter than 28′
- Group 3 – Aircraft bay smaller than 12,000ft2
- Group 4 – Aircraft bay larger than Group 3 but with a membrane covered steel frame
Factors like the presence of jet fuel can affect the fire protection requirements required by the NFPA. For example, if you have a hangar in which only unfueled planes are stored you may only need the addition of a sprinkler system to adhere to code.
Group 1 and Group 2 hangars are fairly similar in design requirements for hangar construction and additional fire protection systems. Basic requirements for a Group 1 or 2 hangars include:
- Constructed of non-combustible materials
- One-Hour walls separating shops and office spaces from bays
- Three-Hour walls separating bays
- Hangar door system must work in emergency
- Aircraft bay columns include sprinklers systems or minimum of Two-Hour construction
- Trench drains large enough to carry full flow rate of any fire suppression systems (sprinklers)
The above features are just the tip of the iceberg in terms of hangar protection. The specific codes you will need to follow can vary so it is important to contact an experienced engineer for exact details.
Additional Fire Protection for Aviation Hangars
In addition to proper construction and fire detection, hangars must also have active fire suppression systems in place. Three common systems include fire pumps, foam spray systems, and water sprinkler systems.
Fire pumps are a water pumps system connected to some type of reliable water source (i.e. public underground water or a static water source). These can provide water and suppression in a number of different ways, depending on the manufacturer’s design. They may be routed to standpipes, water sprinklers, chemical suppression systems, and hydrants.
Water sprinklers are a common tool of simple design, but one that is nearly always mandatory. It is useful to consider a water sprinkler system that triggers individual spouts in the event of fire detection. This can reduce potential damage to aircraft and machinery in areas of the hangar where a fire is not yet detected. Chemical or foam suppression can also be used in addition to water sprinklers.
Another very useful tool for fire protection is smoke curtains. Designed for draft control and deployment in vertical or horizontal fashions, smoke curtains are a useful way of controlling smoke by functioning as a barricade. These can deploy automatically when connected to detection systems and are ideal for closing off offices or workplaces from the rest of the hangar. By controlling smoke and air circulation there is an increased chance of keeping a fire under control until emergency officials arrive.
Fire protection in aircraft hangars should be handled with the utmost care, ensuring that NFPA guidelines are being adhered to and custom additions (i.e. smoke curtains) are considered. Consulting a qualified engineer with experience in large aircraft hangar design and fire safety is the best route to ensuring that the hangar in question doesn’t just meet codes but rather exceeds expectations.