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Fuel Tank Screens - Velocity Retrofit


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#1 TMann

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  • Thomas Mann
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Posted 28 November 2016 - 11:51 AM

There has been a lot of discussion as of late about fuel screens and such on some of the lists.
I inherited a rather poor design and have been trying to make the best of it. The aluminum fuel line leaving the strake tank was very short and definitely too short to flare. The original owner shove a rubber fuel line over it and secured it with a hose clamp.
See Photo: Pic 1
FuelRetrofit_01.jpg
So …. what are my options?


Option 1: Get some Swagelok compression fittings to join to the existing tubing. There may be enough exposed to get the job done.
Option 2: Remove the tubing and start over.


Of course option 2 was the best solution.
I bought some AN867 Aluminum Welding Flanges and drilled a series of holes around the perimeter to act as flox rivets.
Using a hole saw, I drilled through the top layer and removed as much foam as I could. I cleaned it up real good with a wire brush attachment on a drill.
Pic 2 Below:
FuelRetrofit_02.jpg
I made a couple washers out of a single layer of BID using EZ-Poxy to allow for any deviations. One side had the hole a bit off centered from the original so this patched the inside surface to match the flange.


The parts I used were the AN867 flange, a Finger Strainer and a regular AN fitting. Pic 3
FuelRetrofit_03.jpg
Assembled it looks like this. Pic 4
FuelRetrofit_04.jpg
Before I inserted the flange, I vacuumed out any debris I may have missed wit a piece of 1/2” PVC attached to a shop vac.
That was followed by a generous priming of the insert area as well as what I could reach inside the tank to assure there was no damage from the drill. The fiberglass washer was floxed in place followed by flange, a generous helping of flox followed by another 1 ply BID washer the had a hole big enough for the flange to protrude though and overlap the entire area by an inch (which kept all of the flow in place during the cure.)
A little piece of vacuum bag film, some foam rubber and thin plywood. Everything held in place with a piece of 1/2” PVC.


End result (prior to cleanup): Pic 5
FuelRetrofit_05.jpg
The treads were protected with thread seal.


Obviously this would be a lot easier to do on the original build (which is why I bring it up.)
I will be flushing the tanks (without the finger strainer) to remove any leftover debris. This configuration should allow larger particles to pass through in that step.


Perhaps this could be of use to someone else as well.


T Mann - Loooong-EZ/20B Infinity R/G Chpts 18
Velocity/RG N951TM
Mann's Airplane Factory
We add rocket's to everything!
4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

#2 Craig

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Posted 29 November 2016 - 01:55 PM

If you are inside the strake and can retrofit the filter bags Al Wick has evangelized, I would use those.



#3 TMann

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Posted 29 November 2016 - 04:36 PM

I have looked at those and decided against it. The "In-Tank" fuel pump style filters are pretty small and that's a bad place to be too restrictive.

Just ahead of the fuel pump I have a Andair Gascolator which serves that same purpose, has a lot more area and can be purged during you preflight just like the sumps.

 

The "self-cleaning" function of those in-tank filters is basically stuff they have picked up, falling off the exterior when the fuel flow ceases. The gascolator performs the same function and is easier to swap out if needed.


T Mann - Loooong-EZ/20B Infinity R/G Chpts 18
Velocity/RG N951TM
Mann's Airplane Factory
We add rocket's to everything!
4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done




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