Which foam to use for AC AC?

[KirbyWan]

Howdy all,

I'm trying to repair some air conditioning plenums with vent openings for an older military version of a commercial jet. There is a foam on the interior of these plenums that is degraded and I would like to replace it, but I can't tell which of the many options provided by Boings specs this is. The foam is dark grey and feels like the foam used in cheap sponges only less dense (larger cells). There are more then a half dozen foam specs that would qualify to be installed on the interior of an aircraft, but I am not sure which is most suited for air conditioning applications.

There is also a foam on the outside of the plenums which is a bit more dense, but very similar and is also wearing out. If you put your finger on these foams they don't spring back very quicly and if you pick a chunk out and roll in in your fingers it crumbles.

Anyone know what type of foam these could be? If you could provide a manual reference for a Boeing Commercial CMM where this material is used as part of an air crafts air conditioning system I would appreciate it.

Thanks,

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[MintJulep]

As a guess only:

http://www.armacell.com/

http://www/armacell/INETFAQ.nsf/vFrame1/CD493FAD5EF77ECE8025707C00437E3D

Low smoke and flame, halogen free flavors available suitable for the application.

 

[Higgler]

One would assume it's a "fire friendly foam".

An interesting accident happened at my former company when standard gray packing foam caught fire during a lightning arc test. Within 30 seconds you couldn't see the lights inside an EMC chamber. It shocked the EMC lead engineer how quickly the standard gray packing foam created dark black smoke that filled the room. Your description of "dark gray foam" sparked a memory. He also had some white packing foam, it just melted. Foam makes some pretty dangerous gases I believe when it melts.

 

[KirbyWan]

Higgler,

I agree and have made a study of some of the air accidents where smoke inhalation was a prime cause of casualty. Because these are so old I figure any foam that is qualified to a modern Boeing spec for interior products will have better flame and smoke characteristcs then what is on there now.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[Higgler]

One would hope so. Foam is a scary product. We sometimes have to cut foam with a hot wire. Vapors created with the heating/burning from the wires is a scary byproduct to the point that hotwire cutting tools have been outlawed by alot of companies (lawyers I suppose getting in the act).

Foam inside a plenum must be for insulation to keep the cold air from becoming heated. It's possible that an alternative to foam could be use to insulate, like a more modern fiber filled insulation.

Good luck.

 

[KirbyWan]

I was thinking the primary purpose was acoutic. So people near the vent don't hear the rushing air of the air conditioning as it exits the vent.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[kontiki99]

You might check with the maunfacturer for compatibility with flammability requirements of FAR 25.853 and FAR 25.869 (a)(1) and FAR 25.1713 (a) and (c).

I didn't double check these references, but I'm fairly sure they will head you in the right direction.

 

[KirbyWan]

Yeah, I found a manufacturer who can get us a foam certified to a BMS spec which passes flamability requirements. So I went with it and called it good.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.