firewall material

[Eric]

Hello

What matrial do You all use for the firewall?
Mine(kf 3 1991)is made of aluminum.
I don't think that is very fire resistant?
I am thinking of making a new one from stainless steel(0.3mm)

Are there other sugestions

thank You

Eric

[Dorsal]

Mine is SS (not sure of the thickness) which I believe is the current standard.

[Av8r_Sed]

My Model III is about the same age (SN 910) and has a stainless steel firewall.

-- Paul S

[rogerh12]

Eric;

Galvanized steel is very popular too. It's cheaper and certainly easier to work with then stainless steel, and if you screw it up, you’re not out much money (most folks have to special order large stainless sheets). Also, keep in mind the word "stainless" actually describes a large array of types. All the way from Chromium /steel (like used on steak knives) to Nickel/steel (like used on pots and pans) , and about 100 types in-between. When you order Galvanized steel, it’s all mild steel, with only about 1-2% carbon, is easy to drill, cut and bend, but can take the heat of a fire (it’s not as pretty though as polished stainless !!! ).

I personally use stainless pop rivets though, instead of aluminum on the firewall. They hold up better to heat in the event of a fire (look for the high sheer strength type, like kitfox provides). You will have to special order them, to get the good stuff.

Hope this helps

Roger

[DanB]

Roger
The only reason I would stay away from galvanized sheet is due to the off-gasing that may occur in the event of a fire. Galvanized steel is coated with zinc...when zinc is heated, it gives off zinc oxide which will make you sick known as metal fume fever. Usually symptoms like the flu. Welders know special precautions need to be taken to weld the stuff.
FWIW

[rogerh12]

Dan;

Good point, I never heard that about burning zinc, but thats good info. I have some, maybe I will put a propane torch on it and simulate a fuel fire under the cowling, and not the effect (will it just melt away, or gass out).

Roger

[Av8r3400]

Please don't do that, Roger.

Burning the zinc off galvanized metal is not a smart thing to do. The off gassing of zinc oxide is very toxic and 'can' make you sick but can also land you in the hospital with a serious, life threatening case of blood poisoning from breathing the fumes.

(Speaking as a former engineer, welder and machinist. I called the ambulance.)

[rogerh12]

Thanks for the safety advice. Here is my plan (as I was wanted to use Galvanized steel on my kitfox, and am interested in the results):

I think my test will involve using fuel to burn against the galvanized metal, to simulate a fuel related engine fire. Placing fuel in a open tray and allowing the flame to touch the formed Galvanized steel, and also catch the melting zinc in a lower tray (if it does in fact melt away, and not just gas out). The results will be noted.
Fourth of July is coming up anyway, and a number of us (reloader guys) have a bit of extra fun around this time of the year :-) out on the farm , if you know what I mean. That would be a good time to play made scientist again. It is not necessary that I stand near the burn test; I have remote monitoring equipment, so breathing in fumes won't be a concern.
I will update the group on the results (oh, so I guess I better say, unless your experience with volatile chemicals and potentially explosive materials, don’t try this at home).
Roger

[szicree]

When I was in high school metal shop I decided to create a little metal sculpture of a surfer and wave from some material I found in the scrap bin. After I was done welding it I proudly showed it to my instructor expecting at least a "cool". What I got instead was "Do you know that's galvanized steel?". Like a smart-aleck teenager I said "Of course, I don't want it to rust." He then explained to me how you're not supposed to weld on galvanized metal and that I would likely get sick. I did. Spent the next day in the bathroom. I'm told it can be much worse.

Regarding a burn test, why bother? Zinc melts at about 800 F. and vaporizes at about twice that. An engine fire is gonna burn it right off and the fumes (especially from the aft side) are going up yer nose. Having said that, an awful lof of airplanes use galvanized firewall. To each his own, but is stainless that much more money?

[Dave S]

All the comments about zinc fumes being toxic are most certainly true - the classical way people poisoned themselves where I grew up was to take galvanized angle iron salvaged from numerous defunct windmills around the countryside and do the welding thing. A person can also fume zinc off by overheating a brass brazing rod (which is copper and Zinc alloy) Zinc oxide is used for a lot of things including medication, and as a food additive and (this next one should keep people away from it) an ointment for diaper rash.....Sort of the old deal that the difference between a poison and something good is only the amount - and inhalation is the easiest way for someone to overexpose themselves - doesn't take much.

Thinking about this a bit - not so sure a galvanized firewall would be the biggest threat in the event of a fire since there is plenty of resin in the fiberglass parts covering the engine which may get to a person before the zinc ever would - but I guess I favor the angle that cutting out as many potential risks as possible is a good thing - I like the SS firewall and SS rivets idea best.

Dave S
KF7 Trigear
Factory SS firewall