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Nov 29, 2021

On this episode of Fire Code Tech we are discussing aircraft hangars. Diving into the fire protection and design considerations that make these facilities unique and challenging. Check out this episode if you want to learn about codes and standards for aircraft facilities, common fire protection systems, and how other disciplines deal with this occupancy.



Hello. Welcome to the solo cast of fire code tech in these episodes. It's just gonna be me, your host, Gus Gagliardi. There's gonna be a range of topics, but I'm gonna talk about specific technologies, installation, standards, codes, and how they work as well as some other interesting topics that don't neatly fit inside of the context of a normal interview.

Hello. Welcome to another solo cast edition of fire code tech. On this episode, we're talking about hanger, fire protection, something that is near and dear to my heart. So there is a bunch to dive into for hanger fire protection. So in this episode, we're gonna look at some of the common fire protection systems as always the codes and standards around the subject.

We're gonna take a look at some of the other design features associated with hangar fire protection and hangers in general, they provide a unique set of challenges for design, um, for all trades, not just fire protection. And so, yeah, this is an episode that I've been thinking about for a while and. I have quite some experience with, so I hope you enjoy, and we will do a couple episodes on this subject.

Don't forget to subscribe. So you never miss an episode and follow us on social media. Oh. And if you feel so inclined, it would be a huge help. If you would give us a five star review on apple podcasts, let's dive into the show. So standard. Disclaimer, here we are looking at the fire protection hazards and codes and standards through the lens of the codes and standards in the United States.

Um, I will be giving reference to more specifically the adopted codes and standards in Oklahoma. So right now the state has adopted I B C 2018. That is a bit of a preface for our first topic, which is what are the codes and standards around hanger fire protection. So as you can imagine, there are specific requirements in the building code for aircraft hangers.

That section specifically is section four 12, which. Aircraft related occupancies, as we've talked about before chapter four has special occupancy related chapters. And when you have a building or a facility type that is, uh, especially dangerous or has unique properties that, um, require more advanced fire protection features generally you'll find a lot of these features in chapter four of the building.

So there are some provisions in the building code that are mirrored within the standard for aircraft hangers, which is an FPA 4 0 9. Let's talk about a couple of these special requirements that are located in the building code. Once again, that's section four, 12 aircraft related occupancies. So our discussion today will focus more on aircraft hangers, but.

Section four 12 in the international building code covers a variety of buildings that are associated with, um, many types of Aircrafts. So one of those buildings is, uh, Eric traffic control towers. I don't have much experience with these buildings, but they have, uh, many special requirements due to the abnormal configuration of these buildings, uh, abnormal in that they are very tall.

And, uh, have a limited number of egress points because of their height in configuration. The discussion today will be centered predominantly on aircraft hangers. Now there are a couple of different types of aircraft hangers. Um, there are light and heavy maintenance aircraft hangers. There are, um, fuel cell hangers, which is where they do repair on.

The fuel tanks and compartments of Aircrafts. And then there are paint hangers, which is where they do the commercial painting for the exterior of the aircraft. Um, and then there are manufacturing hangers, so where airplanes are assembled or manufac. So, as you can imagine, there are, um, further requirements for each of these special type of hanger, but the most common type of hanger would be the, the light or the heavy maintenance hangers.

Um, so we'll focus our discussion on that aircraft hanger for today. So the beginning of section four 12 for aircraft related occupancy. 4 12 1 general aircraft related occupancies shall comply with sections four 12 through 4 12, 7, and the international fire code. So in four 12, we can see specific sections that top talk about construction types, um, and.

Construction types and fire area play a huge part in what fire protection systems are required in the facility. So before we talk about hangar classification, let's just start with the preface that if you can think about it as a fire and life safety system, likely the classification of the building as an aircraft hanger will affect that.

Life safety system. So just for conversation sake, let's list off some of the life safety features that will definitely be impacted. If you have a aircraft maintenance facility that you're designing. Egress building construction, fire, alarm, fire, suppression, fire rated fire, separated assemblies. There are other design features that are impacted like the sloping of the floors and the type of heating or conditioning that you will have selected.

Oftentimes aircraft hangers are not conditioned, so they'll be heated, but not cool. Depending on the fueled nature of the aircraft, whether it is fueled or UN fueled or what type of work is being done in the hangar, there might be hazardous classification of the electrical system. So that class one D one or class one D two.

Hazardous classification for electrical is a topic for a whole video. But for the purposes of this discussion, there are parts of the hanger which can be class one, div one, or class one. Diviv two, which effectively means that there are in class one, di one, there are situations that could be hazardous for flammables and combustibles present.

At all times and class one, dip two is, um, in some instances there will inadvertently be flammables or combustibles, but so that adds a huge cost for, uh, rated explosion rated, uh, electrical devices and hanger, depending on what kind of work you're doing inside of the aircraft. Hang. So before we talk about what are the different fire protection approaches for aircraft hangers?

We have to talk about the classification of aircraft hangers. So there is group 1, 2, 3, and four aircraft hangers, and then there are, um, other chapters in NFP, 4 0 9 that have huge sweeping implications for the hanger is. Pain hangers, which is chapter 10 in the latest edition of NFPA 4 0 9, uh, as always, but more importantly with hangers, you need to know what the addition of codes and standards you're working with.

Um, in the reason why it's so important for aircraft hangers is there are only versions of NFPA 4 0 9 made approximately. Every four years. So there are huge, huge changes in what is allowed between the additions. Um, the 2011 edition. Is much different from the 2016 edition is extremely different from the 2022 edition, which is the latest version that has come out.

This can mean the difference of needing two fire protection, water storage tanks for your facility, or maybe not needing them at all with the 20, 22 edition of the. So it really pays to understand codes and standards and what version of the standard that you're using. So let's get back to hanger classification, cuz this is the first step for determining what fire protection systems are required for your.

So, as we talked about before, there are four types of hangers and the most hazardous type of hanger in the group, one through four categories is group one. So depending on the maximum fire area inside of your hanger and the construction type. You can classify your hanger. So once again, we're looking at the 2022 edition of N FPA 4 0 9, which is the standard for aircraft hangers.

And more specifically, we're looking at chapter four, which is aircraft hanger groups, chapter four, lays out the process for determining which group your hangar is in, which will in turn stipulate. A lot of requirements. The protections and the features that your hanger will need to have. So we start off with the most hazardous group, which is the group one aircraft hanger, and it says in 4.1 0.1, a group, one aircraft hanger shall have at least one of the following features and operating conditions in aircraft access door, height of 8.5 meters or 28.

Single fire area area, a single fire area in excess of 3,716 meters squared or 40,000 square feet provision for housing of an aircraft with the tail height over 8.5 meters. So as you can see here, the two biggest drivers for if you have a group one aircraft hanger. The square footage of the aircraft hanger or the height of the aircraft.

So over 28 feet servicing an aircraft with over 28 feet of a tail height or door height. So if you can get a aircraft with a top clearance up 28 feet, then you are meeting this requirement. So. Yeah. So you can tell briefly by taking a look at the square footage of the largest aircraft hanger bay. So let's take a look at group two aircraft hangers, 4.1 0.2, a group two aircraft hanger shell have both of the following features in aircraft access door of a height of a 0.5 meters or 28 feet or less.

A single fire area for specific types of construction in accordance with table 4.1 0.2. So for group two in group three aircraft hangers, there are tables which have construction types, which give additional allowances for, um, how large or small your fire area can be before it is a group two or group three aircraft hang.

So group one is nice and neat at 40,000 square feet and, and 28 feet of door height, but group two in group three, have a little bit more nuance as they take into account the, uh, square footage in comparison to the construction type. So under there are a couple different thresholds, um, 30,000 square feet, 20,000 square feet, 15,000 square feet.

Um, and based on, you know, if you're type one through five construction, you can be within these group two and group three hangers. After you determine which group of hanger that you are classified, as you would go to the specific chapter for that group of hang. New to the 2022 addition of the standard.

There is a performance based design approach. I won't talk about that in this episode, since I have no, uh, experience with performance based design, really, uh, especially not in the form of aircraft hangers, since it is so new, but thought it was worth noting chapter six, which talks about aircraft hanger groups and their fire protection requirements.

Wanted to end with 6.1 0.1, which will be a starting place for our next discussion on aircraft hangers, which states some of the fire protection systems that are allowed for a group. One hanger that section states the protection of aircraft storage and servicing areas for group one aircraft hangers shall be in accordance with any one of the following home water dealers system as specified in 6.2 0.2.

In addition, supplementary protection systems as specified in 6.2 0.3 shall be provided in hangers housing as single aircraft. Having wing areas greater than 3000 square feet. Part two, a combination of automatic sprinkler protection in accordance with 6.2 0.4 and automatic low level low expansion foam system in accordance with 2.6 0.2 point.

Part three, a combination of automatic sprinkler protection in accordance with 6.2 0.4 and an automatic low level high expansion foam system in accordance with 6.2 0.5. So this section basically gives allowance for the combination of fire protection systems, which will be allowed to protect group one aircraft hangers.

As a recap, there are high expansion foam. Or low expansion foam in combination with sprinklers. That's gonna do it for this episode of fire code tech. Thanks for listening. Thanks for listening, everybody. Be sure to share the episode with a friend, if you enjoyed it, don't forget that fire protection and life safety is serious business.

The views and opinions expressed on this podcast are by no means a professional consultation or a codes and standards interpretation. Be sure to contact a licensed professional. If you are getting involved. Fire protection and or life safety. Thanks again. And we'll see you next time.