REFLECTOR:fuel tank leak testing

[Alexander Balic]

You can also use freon (134a) and a freon leak detector and the advantage of
that is that freon is non flammable- not sure off hand how much the
detectors are now, but if you can't borrow one from your friendly garage or
Air Conditioning repair shop, O-Reilly has them.
Yes, you need to be really careful with the pressure in that tank, we used
to be able to move 5,000 pound injection molding dies with about 20 psi
using an air pallet- basically it is just a steel pad with a rubber skirt at
the bottom to keep the air in, and you lift the objects like a hovercraft,
then all you need to do is push them around by hand- it always amazed us how
much you can lift with just a few psi of air under there....

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of richard@riley.net
Sent: Saturday, July 05, 2003 7:47 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:fuel tank leak testing


If you're at a few PSI, you may have caused the leak blowing the skin off
the spar.  At a few psi you have thousands of pounds of peel force.  As one
of the other posters said, you shouldn't pressurize it more than by mouth -
less than a PSI.

You can get a gas detector cheaply at an RV supply place.  Drip some
propane in the tank, cover the fuel port with duct tape, run the detector
around the area and play with the sensitivity, you'll get it isolated.

For sealing it, you can put a slight vacuum on the tank with a shop vac
(don't tape the hose in, you want the connection leaky) use a heat gun to
get your epoxy very thin (it will exotherm, be careful) and dab it into the
leak.  Or use a syringe - good ones can be gotten from the Veterinary
supply store.

At 12:01 PM 7/5/03 -0500, you wrote:
><?xml:namespace prefix="v" /><?xml:namespace prefix="o" />
>I'm still having difficulty finding and eliminating my fuel tank
>leaks.  Let me review what I have done.
>
>My two small bulkheads between the large rear bulkhead and the main spar
>have already been installed, but I can get my hand through the opening.
>
>I reduce the pressure on my air tank/pump to a few psi (so I can easily
>stop the flow with my finger) so as to not damage the tank.  I can hear
>the air escaping from behind the large bulkhead.  When I first began
>working on it, I could feel air coming from that area just by reaching my
>hand in there.  I have used a soapy solution, but cannot see any
>bubbles.  I have used this technique with tires  before with good
>results.  However, the pressure in those cases were over 30psi.
>
>I then tried using the tubing as some of you suggested.  The sound is not
>localized and seems to be very steady all along the rear bulkhead.
>
>I have applied sealant all along the seam using a paint brush attached to
>a pair of sticks so that I can adjust the paint brush after getting it
>through the small bulkheads.
>
>It is hard to tell without quantitative measurement, but I think it is
>improving some.
>
>I also tried to spray epoxy in the cavity using a water sprayer.  The
>epoxy and cabasil were too think to really spray.
>
>Any help would be appreciated.

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