Fuel tank pressure testing

[Roger and Alice Hoffman]

I'm ready to pressure test the right wing fuel tank and am looking for ideas
on how the rest of you sealed off all the fittings and what kind of
connection did you setup to pump air into it? I understand a balloon over
the fuel fill opening is used to watch for pressure change.

Thanks for your help.

Roger Hoffman #687R
Eugene, OR USA




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[Wayne G. O'Shea]

Roger, all the fittings can be simply plugged with threaded pipe plugs and
don't forget to use the same thread sealer on them as you will with the
final fittings. DO NOT USE TELFON TAPE! On one of the fittings you need to
install a valve fitting. The best thing to use is called a snifter valve.
This is like a bicycle tire stem, but has pipe thread on the opposite
end.You will find them in the water well accessory area of you local
plumbing supply house, as they are used for pressurizing the accumulator
tank.

And oh ya! That's not a balloon you need, as they are porous. Must be the
latex variety of "balloon" ("nudge, nudge, say no more") or a latex glove.
Three or four layers of elastic band should hold it in place on the filler
neck. Blow it up until it's well inflated, resembling a town's water tank,
and leave it alone. IF you have a tight tank it will not deflate for some
time and then due to temperature/pressure changes from day to day, the
biggest guarantee you have of a leak proof tank is when the "balloon" is
inflated inverted inside the tank! This shows the tank will hold a vacuum
which would be impossible if you had a flap of Proseal acting as a check
valve, that was sealing a due to positive pressure as it would swing out of
the way during the vacuum stage. I recently had a latex glove on a tank for
4 1/2 months, that came out to great me just about every day when I turned
the heat up in the shop. Absolutely guaranteed that there are no leaks on
this one.

My two cents, once again, FWTW
Wayne G. O'Shea
www.irishfield.on.ca

----- Original Message -----
From: "Roger and Alice Hoffman" <rognal@mindspring.com>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, June 17, 2001 6:37 PM
Subject: Fuel tank pressure testing


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I'm ready to pressure test the right wing fuel tank and am looking for

ideas

on how the rest of you sealed off all the fittings and what kind of
connection did you setup to pump air into it? I understand a balloon over
the fuel fill opening is used to watch for pressure change.

Thanks for your help.

Roger Hoffman #687R
Eugene, OR USA

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[Legeorgen]

Roger,

Plug the fuel ports with the plastic plugs like the kind your Brake cylinder
comes with to keep out contamination. Screw your fuel valve into the main
fuel port and blow in it until your balloon inflates then close it (the
balloon just needs to stand up). Be careful... a temperature change of only a
few degrees can cause the balloon to deflate or even be sucked into the tank.
That doesn't qualify as a leak! Good luck.

Bruce G




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[klehman]

You can also use a length of clear plastic hose to make a water
manometer. 2 feet of water differential equals 1 psi of pressure which
you can then monitor for change. On mine, every time there was leakage,
soap bubbles proved it to be tiny bubbles around the latex glove sealing
the fuel cap.

Ken

Legeorgen@cs.com wrote:

Roger,

Plug the fuel ports with the plastic plugs like the kind your Brake cylinder
comes with to keep out contamination. Screw your fuel valve into the main
fuel port and blow in it until your balloon inflates then close it (the
balloon just needs to stand up). Be careful... a temperature change of only a
few degrees can cause the balloon to deflate or even be sucked into the tank.
That doesn't qualify as a leak! Good luck.

Bruce G

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[Roger and Alice Hoffman]

Bruce G,

I don't have a brake cylinder yet, but I think I know what type plugs you
are referring to. Any suggestions on where I can obtain them?

Thanks,

Roger Hoffman #687R
Eugene, OR USA




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[klehman]

Why not just use whatever your local hardware store has? Look in
plumbing for pipe thread plugs in brass or steel. The small ones are
1/8", the largest was 3/8", and I think there were some 1/4" ones as
well. You could probably even use the CAV-110 fuel drains on the 1/8"
pipe thread holes.
Ken

Roger and Alice Hoffman wrote:

Bruce G,

I don't have a brake cylinder yet, but I think I know what type plugs you
are referring to. Any suggestions on where I can obtain them?

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[Legeorgen]

Hi Roger,

You can get brass plugs and fittings for these fuel ports at an auto parts
store like NAPA, if you don't have any plastic ones. The're used for gas
lines. I think this is what MAM sends out for your primer lines and fittings
if you get the firewall forward kit.

Bruce G




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