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  #41  
Old 06-12-2011, 02:16 PM
Experimental Chaos's Avatar
Experimental Chaos Experimental Chaos is offline
 
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Default Envalope Please......

Augh! Don?t make me think, it looks like there are pros and cons, to several firewall sealants. Dan, what would you use, with what you know now, to seal a firewall?
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  #42  
Old 06-12-2011, 03:38 PM
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Full failure at less than 2 minutes; the bushings melt, leave a gap, and hot gas is free to do its thing. The CS1900 and Resbond plugs remain pretty much intact and block most of the opening, while the wire stubs collapse the soft silicone chars and fall out of the holes.

I've moved the torch to aim directly at the welded steel pass through; note the new location of the glowing hot spot. The intumescent FireBarrier is squeezing out everywhere. The fitting remains gas tight despite the heat.



Front side again. The CS1900, FireBarrier, and Resbond strips are still hanging. The torch is aimed directly at the welded tube fitting, which is glowing red. In another minute or two the red hot copper wire core will ignite the tefzel insulation on the opposite side, at which point I ended the burn.



Hot-side chars collected post-burn. They are soft and fragile, puffballs really:



Note the CS1900 char still intact on the wire. It was tougher than the silicone chars. Also note the Resbond strips. Although entirely intact, they released from the stainless with no effort.



Conclusions are subjective, and my opinion...

CS1900 looks like an excellent sealant for use between fay surfaces and in thick sections with mechanical fixation. Good resistance to direct flame but with a lot of smoke and burning, so I'd be very careful about allowing any more than a trace to show on the cabin side of a firewall. Adhesion is poor. Mixing is a PITA.

Resbond can be called fireproof for our purposes, or close to it. I noticed no smoke or outgassing. The catch is its hardness; it has little flexibility when cured and none after heating, when it become about like a charcoal briquette. I did a separate test by applying a sample to stainless sheet. After cure I bowed the stainless 20 degrees and the Resbond strip popped off intact; it doesn't bend. Although the hands-down champ for fire resistance if used in the absence of flex or vibration, I doubt it will stay sealed in a highly dynamic application. Still, very interesting material...

FireBarrier is easily the best of the silicones. It has excellent cold adhesion and about the same hot adhesion as Resbond. Obviously flexibility and dynamic sealing is good. The char is not as tough as CS1900 char and may blow away in high velocity air, and for the same reason is not as resistant to direct flame exposure. It is highly intumescent, expanding to fill voids as other components burn away.

Biotherm had poor hot adhesion. Ultra Copper also had poor hot adhesion and was surprisingly flammable. I'd pass on both.

None are "best". Each has particular properties which need to be carefully considered for a particular application. Sorry, building airplanes requires some thought.

Me? I used FireBarrier silicone in two ways.

Cables and wires got tubular steel fittings like the one in this test. In the real world FireBarrier is intended for fire sealing cable and pipe passages through walls and ceilings. The surface char insulates the remaining sealant, which is well supported inside the passageway. If the pipe or wire burns away the intumescent property seals the void. No surprise that the same principles work in this airplane adaptation.

The firewall perimeter got a filet of FireBarrier before adding the foil/insulator sandwich, the edges of which were sealed with another filet.

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Last edited by DanH : 09-10-2018 at 01:26 PM.
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  #43  
Old 06-12-2011, 05:11 PM
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Jamie Aust Jamie Aust is offline
 
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Outstanding job Dan !
Thanks for doing the test and showing the results.
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  #44  
Old 06-12-2011, 06:02 PM
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Experimental Chaos Experimental Chaos is offline
 
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Default THANK YOU DAN!

I agree with Jamie, Outstanding! Truly, you may never know, but you could have very well saved someone?s life though your efforts. I?ve seen on other threads, where people have responded, ?ya, ya, but I think I?ll just use bubble gum, because I don?t plan on having an engine fire.? It?s truly a chilling idea, that that could be their last thought.
Thank you again, for your efforts, and insight!
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  #45  
Old 06-13-2011, 06:56 AM
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Dan Langhout Dan Langhout is offline
 
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Default Many Thanks!

Thanks Dan for your efforts! One useful outcome for me is that as good as CS-1900 seems to be, it doesn't appear that it has any particular advantage over Firebarrier 2000+ for standard firewall sealing uses (e.g. sealing the joints between the skin and firewall flange or other fay sealing situations).

Quote:
Originally Posted by DanH View Post
<snip>
Me? I used FireBarrier silicone in two ways.

Cables and wires got tubular steel fittings like the one in this test. In the real world FireBarrier is intended for fire sealing cable and pipe passages through walls and ceilings. The surface char insulates the remaining sealant, which is well supported inside the passageway. If the pipe or wire burns away the intumescent property seals the void. No surprise that the same principles work in this airplane adaptation.
</snip>
I am taking this approach as well (tubular fittings) but was intending to use clamped firesleeve inside and outside the tube due to maintenance/serviceability issues. (I did make my own tubes - thanks Dan!) Just filling the tube with sealant is much simpler and obviously works fine. I would just be concerned with the difficulty of, say, replacing a control cable and trying to dig all that sealant out of the tube later. Any thoughts?
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  #46  
Old 06-13-2011, 09:21 AM
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DanH DanH is online now
 
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Quote:
Originally Posted by Dan Langhout View Post
....as good as CS-1900 seems to be, it doesn't appear that it has any particular advantage over Firebarrier 2000+ for standard firewall sealing uses (e.g. sealing the joints between the skin and firewall flange or other fay sealing situations).
The CS1900 is more resistant to direct flame and has a tougher char, but neither matters much in a fay seal. On the flip side, I was surprised to see how much flame and smoke it generated in the course of forming that char.

Quote:
I am taking this approach as well (tubular fittings) but was intending to use clamped firesleeve inside and outside the tube due to maintenance/serviceability issues.....Just filling the tube with sealant is much simpler and obviously works fine. I would just be concerned with the difficulty of, say, replacing a control cable and trying to dig all that sealant out of the tube later. Any thoughts?
Yeah, the "pump it full" method is fast and easy to install, but I'd hate to try adding a few new wires to a bundle. Not so worried about engine control cables. I'd be replacing them for a reason so I wouldn't care about trashing them during removal.

Perhaps a mix of the two methods? In the building construction firestop application, the core of the pass-through is often packed with a fiber insulator around the pipes or wires, then the sealant is applied in a layer over the fiber, sort of like a rubber stopper in each end of a packed tube.

All design is a matter of carefully considered compromise.
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Last edited by DanH : 06-13-2011 at 09:24 AM.
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  #47  
Old 06-13-2011, 10:25 AM
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Mike S Mike S is offline
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Talking Dan for President

Dan, I will echo the sentiment others have already put out there.

Your efforts are a real asset to the entire VAF community, and there is a good chance you may save someone from a future injury, or death.

The photos of various products failing miserably are pretty convincing to this old fireman.

I will be removing my firewall insulation before my next flight, based on your testing.

I think the information in this thread is of such value, I am going to make it a "sticky" for easier finding in the future. And added "fire safety" to the title.

Again, thanks for all your efforts, and for sharing them with us.
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Last edited by Mike S : 06-13-2011 at 10:36 AM.
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  #48  
Old 06-13-2011, 02:06 PM
bkthomps bkthomps is offline
 
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DanH, is it possible to use the 3M firebarrier multiple times? How are you storing it for reuse (if so)
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  #49  
Old 06-13-2011, 04:48 PM
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Quote:
Originally Posted by bkthomps View Post
DanH, is it possible to use the 3M firebarrier multiple times? How are you storing it for reuse (if so)
It's like any other RTV silicone...seal it from the atmosphere. I tape up the cut nozzle with aluminum foil duct tape.
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  #50  
Old 06-13-2011, 06:48 PM
chaskuss chaskuss is offline
 
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Post Another test requested

[quote=DanH;549778]Ok, here we go. Sorry to take so long. Had to assemble a new fire rig as the old one was long ago dismantled and recycled, and I decided to allow plenty of cure time for the test materials.

First, the candidates:



Cotronics Resbond 907GF (courtesy of Don Pansier)
Rectorseal Biotherm 100 (courtesy Dan Langhout)
Flamemaster CS1900 (courtesy Dan Langhout)
3M FireBarrier 2000
Permatex Ultra Copper

snipped

Dan,
Sorry, but I'm very late coming to this thread. Thanks to everyone, especially Dan, for all the comments & ideas. I believe, however, that I have one consideration that no one has mentioned yet. How will these products hold up in the presence of aviation fuel and oil??? A great product which dissolves in gasoline or oil is next to worthless it would seem to me.
I ask, because silicone based products like the Permatex Ultra Copper are dissolved by gasoline. As an auto mechanic, I used to regularly use gasoline as a solvent to clean RTV silicone from auto parts. I'm sure many of you will recall the disastrous results pilots have had when they used RTV on carburetor parts. [ A number of forced landing caused by RTV ending up jamming float needles are listed in the archives of this forum]
Since the 3M Fire Barrier 2000 is silicone based, I wonder how it would hold up on the front side of the firewall, where it will be exposed to fuel and oil??
I note that the CS 1900 is listed as "fluid resistant". I believe that this is the sort of consideration that takes place when one designs a product for a specific environment [like an aircraft's FWF]
Perhaps it would be wise to cure these products and submerge them in 100LL and 93 octane auto fuel for a few days to see what happens to them. Obviously, the 3M product is only partly silicone, so perhaps it will hold up? Or maybe the other components in it will fair even worse when combined with fuel?
For those of you who already have Fire Barrier 2000 installed, it may be best to take care when fuel is spilled onto the firewall to clean it off immediately. My experience with fuel and silicone products is that exposure for a short period is not a big problem. Continued contact IS an issue. How about a solvent test Dan??
Perspiring minds want to know! :-)
Charlie Kuss
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