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RV-12 fuel tank ? how much tank sealant required?

John-G

Well Known Member
About to begin assembling the RV-12?s fuel tank. It is one of the newer tanks without the site gauge on the side and has the holes for Moeller fuel gauge and the new fuel tank venting method. Originally, I was considering ordering a handful of the MC-240-B1/2 1 oz kits of fuel tank sealant from the Van?s site figuring it could be used on the fuel tank and the remaining kits used on some of the other locations on the RV-12 which require sealant. However, just discovered the one ounce kits only have a 30 minute work time, which surely is not enough time to assemble the whole fuel tank.

I see there is the MC-236-B1/2 Tank sealant in a 3.5 ounce size with a 2 hour pot life and was wondering if anybody has used it to assemble their RV-12 tank? If so, is 3.5 ounces enough material to get the job done and can it be completed within the 2 hour limit?

I don?t have a gram scale so do not want to purchase a quart which requires weighing out the material and catalyst.

Comments appreciated ...happy building,
 
I used the quart kit. I didn't have a gram scale either but got one from Harbor Freight pretty inexpensively. Ended up using the gram scale for other stuff anyway (fibergass mixing, etc.).
 
My experience (s)

The 3 1/2 oz are very good. You will be better off not trying to do it all at one time. Buy 3 of them. 2 for the tank, and one for misc firewall sealant etc. Have used the small ones. Set up too fast for a bigger job. Great for taking front plate off etc. Hope this helps. Others may feel much different. I have done about 4 - 5 tanks ( mine and others ).
 
The MC-236-B1/2 (if it is really B1/2) is also a 30 minute work time (the 1/2 means half of an hour).
Sealant labeled B2 is 2 hour work time. I will look into this, the B1/2 might be a typo.
Follow-up - If you order the MC-236-B1/2 you will get a a 2 hr cure sealant. The product was changed at some time in the past, and for reasons I will probably never understand, the part # was left as is from the original. If you order based on the product description, you will get what you want.

A tube of B1/2 sealant might be a challenge for a beginner to avoid having it start to harden up. The last thing you want is to rush for the sake of the sealant and end up with a leak.

As mentioned already, you by small scales real cheap that are more than accurate enough.
 
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Get the quart size and a cheap HF scale. This is really not a big/expensive/complex deal. It's nice not having worry about having sufficient sealant to complete the various sealing jobs. Besides, you will find many useful purposes around the house and shop for the leftover sealant!
 
I do not think that fuel tank sealant should be used to seal the firewall. I set on fire some cured sealant with a propane torch. After taking the flame away, the sealant continued to burn. The smoke is not something that you would want in the cockpit. Is there something better to seal the firewall with?
 
fuel tank sealant

FYI its easer to work on the fuel tank in several steps and time also the sealant is used on the wing tips.
 
I do not think that fuel tank sealant should be used to seal the firewall. I set on fire some cured sealant with a propane torch. After taking the flame away, the sealant continued to burn. The smoke is not something that you would want in the cockpit. Is there something better to seal the firewall with?

I suggest that a read of the excellent posts here is a good starting point for selecting a firewall sealant:

http://www.vansairforce.com/community/showthread.php?p=549778#post549778
 
John,
Add my vote for the Quart Kit and a cheap digital mail scale that measures in ounces and grams. You'll use the proseal in a number of places, it is good for a loooong time if you store it cool, AND it's real handy for other things e.g. shoe repair (just sayin'). And it's so sticky and strong you can impress your friends by suspending an elephant that is glued to a chain with an single drop of the stuff! Kidding! I'm Kidding! Pretty sure it's never been tried. Hmmm...well we are experimenters...
 
Thanks

Thanks for the input guys ?. guess an inexpensive gram scale is on the horizon.

I was just trying to avoid purchasing a gram scale because pre-measured is seemingly easier. Plus, I can just hear it now ? ?Did you hear about that guy with the pony tail down at hangar 45? ? Airport security found him with a gram scale and two large bags of white powder?. Honest officer, it?s only micro balloons and flox.
 
Thanks for the input guys ?. guess an inexpensive gram scale is on the horizon.

I was just trying to avoid purchasing a gram scale because pre-measured is seemingly easier. Plus, I can just hear it now ? ?Did you hear about that guy with the pony tail down at hangar 45? ? Airport security found him with a gram scale and two large bags of white powder?. Honest officer, it?s only micro balloons and flox.

We used syringes to measure out the correct volume for proseal.
 
Measure tank sealant by weight

Alex - Obviously measuring by volume worked OK for you.

However, the product application data sheet does say to measure the two components by weight.
 
Alex - Obviously measuring by volume worked OK for you.

However, the product application data sheet does say to measure the two components by weight.

John,

I will check on the weekend but if I remember right the tin had an mix ratio by volume as well.

Alex
 
resurrecting an old thread regarding the 12iS tank..

you will need 3 batches -- two for the tank and one for other things (fairings, etc).

The instructions call for you to familiarize yourself with the build and says you'll need 3 hours of uninterrupted work for the tank. I found that to be true (even with rehearsing the build and working without any delay).

In 2 hours, I was only able to finish the top half of the tank (excluding the main access hatch and the two boomerang doublers on the side of the tank (12iS)).

I had a 6oz tube which was ample. After 2 hours, I probably still had 2oz unused.

If I had a helper who could dip the rivets for me and another that did clecos, I probably could have finished the tank in one session .. and in that case, I'd recommend 1 6oz tube.

For solo work, I'd recommend three of the 2-hour 3.5oz cartridges
 
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