Hangar Doors Held Open/Closed During Fire?

2/28/2022

We're working on an aircraft hanger with a foam system. I can't quite nail this down, as NFPA 409 and the UFC don't spell this out - do the hangar doors need to be open, or closed, in case of a fire or to test the foam system?

Again, don't see any guidance spelled out in either standard. Thanks in advance.

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19 Comments

Alex

2/28/2022 08:01:10 am

Hi,

I personally have no experience regarding NFPA 409 or aircraft hangers.

I did do some research this morning and found that the current foam suppression systems are under a lot of scrutiny. This comes from a series of false activations. Fire investigators are stating this is due to improper system design and lack of proper commissioning.

If you are currently trying to write a sequence of operations to test a new system, I would make sure to review the current design and any/all proposals to ensure no corners are cut.

Best of luck!
Alex

Heather C Barreto link

2/28/2022 01:01:31 pm

This is true!. Thank you for your comment.

Dave

2/28/2022 03:24:28 pm

What about the hangar door question?

Jack G

2/28/2022 08:11:39 am

I have a pic of an operating deluge system in a helicopter aircraft hanger. Wish I could attach it.

Moderator

2/28/2022 08:12:33 am

Send it to us at [email protected] and we could probably get it hosted.

Heather C Barreto link

2/28/2022 01:01:48 pm

Would be great!

Derek

2/28/2022 08:22:39 am

2022 NFPA 409 only states that a functional test of the doors needs to be done annually with no flow. In addition, 8.2. allows for open doors for multiple types of systems. I guess it's AHJ interpretation?

Heather Barreto

2/28/2022 01:02:40 pm

I will check this! Thanks

Dan Wilder

2/28/2022 08:28:57 am

I've never had this requirement come up (not saying it isn't a requirement somewhere but the commercial & military hangars I've done have not required it). We actually test with the doors partially open anyway (mostly for containment so the foam doesn't roll out onto a runway) and for the looky-loos who are there to witness..

There would be too many variables for things in the path of the door (planes, vehicles, people) to set something like this up. What pressure/resistance is needed to stop the doors? Do they stop or do they retract? How do you release the doors for access?

The discharge amount and depth of foam typically account for worst case scenarios (if you've ever been in a scissor lift within a hangar and realized that the required 6' of foam quickly turns into 10'-15' and you've got to raise up to not take a bath :-)..)

Heather Barreto

2/28/2022 01:05:01 pm

Thanks!.. Well I guess I need to check with AHJ about what they want

Glenn Berger

2/28/2022 08:42:08 am

I have required the doors to be closed to ensure that the depth of the foam is obtained.

Brad K

2/28/2022 08:53:47 am

First, I recommend closing the doors for the test. You DO NOT want air pressure or wind to take test foam out and create potential for concern near an active air strip. Not to mention EPA issues.
For the code: 409-7.4.5/7.5.7 (2016) We test to within 5 ft of perimeter walls and doors. The foam will continue to spready after you kill the discharge so containment is easiest with the doors closed. A 2 to 3 minutes discharge can easily create 5 ft of foam in the hangar if all proportioning and pressures are correct. Have a meeting with your foam manufacturer if needing more input and ideas.

Heather Barreto

2/28/2022 01:08:26 pm

Awesome Comment. Thanks for your advice.

Ryan G

2/28/2022 08:45:22 am

The idea of a foam system is to smother the fire. I order to accomplish this, you need to contain the foam. To contain the foam, the hanger door needs to be shut. To work effectively, the door should be closed prior to the system discharging.

Heather Barreto

2/28/2022 01:09:05 pm

Thank you for your comment! very hepful

Jesse

2/28/2022 08:59:26 am

Its AHJ interpretation usually.

I once had a FBO client that fired their incumbent insurer because the loss control guy measured a hangar with a laser and hit one of the optical sensors and tripped the system. You'll only do that once.

Zackery Geddies

2/28/2022 09:50:32 am

Take a look at NFPA 11 the Standard for Low, Medium and High Expansion Foam section 7.7 Operation and Control of Systems and 7.12.4.1.1.2. Doors are required to close automatically before or simultaneously with the start of the foam discharge.

Heather Barreto

2/28/2022 01:09:42 pm

I will check this ! Thank you for your comment.

David Toshio Williams

2/28/2022 02:46:17 pm

A "little" sidebar... we have a job under construction at an Air Guard Base and we got direction from the Government that work on the HE foam was to stop and the job would be changed to a conventional (preaction in this case) sprinkler system only. Apparently the loss of planes is less of an issue versus the risk/liability of the AFFF and HE systems. Sounded like a change nationally.

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Hangar Doors Held Open/Closed During Fire?

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