I suggest that you re-think your sequence. Perhaps you scheme will actually
get the tank clean but since both acetone and isopropyl alcohol are polar
solvents they won't do a thing to remove oils which are by definition
non-polar. Water is another rather well known polar solvent and I'm certain
that you realize that water alone won't remove the oils. A lighter
non-polar solvent (such as paint thinner) will get the oils out and then the
detergent (polar at one end of the molecule and non-polar at the other end)
in water will get rid of the residue. Acetone will do a nice job of
gathering up the water after getting rid of the oils. The fabric softener
will probably adhere nicely to the tank's surface (that's how it works).
In the spirit of the old adage about being better safe than sorry, I must
point out that gasoline is also a non-polar solvent and some folks have been
known to set themselves on fire using it as an oil removing solvent. I
would not expect anyone on this list to try for a Darwin Award, so I
probably did not even need to mention this.
Best regards,
Rob Housman
Europa XS A070
Rotax 914
Airframe complete
Avionics a work in progress
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Andrew Sarangan
Sent: Saturday, November 09, 2013 3:58 PM
Subject: Re: Europa-List: Fuel tank fluorination
Bob
Regarding cleaning, all traces of oil, paper and water has to be removed.
That is about all they said. Apparently these items can 'burn' in fluorine
and cause damage. I am flushing the whole tank first with dishwashing
detergent and fabric softener. This reduces static cling and allows the fine
powdery plastic to be flushed out. I got a surprising amount of particles
come out even after I had vacuumed everything inside. Then I plan on
plugging the holes with cork and shake the tank with a gallon of acetone,
drain it, and then repeat with isopolyl alcohol. Acetone removes oils and
IPA dehydrates all surfaces. That's my plan anyway.
Regarding timeline, apparently they don't always run the automotive-level
fluorination process, so it depends on when we deliver the parts there, and
what they have in their pipeline. But they said it shouldn't be more than 1
or 2 weeks.
My plan is to drive my tank over there sometime this coming week. But if you
are interesting in joining, I am willing to wait.
On Sat, Nov 9, 2013 at 2:54 PM, Robert Borger <rlborger@mac.com> wrote:
>
> Andrew,
>
> Two questions:
>
> 1. What is the recommended cleaning procedure to ensure the tank isn't
> fried?
>
> 2. What is the timing on procedure?
>
> I have my new tank almost ready to install. Just a few more supports
> to make up and the tank will be ready to go back in.
>
> Blue skies & tailwinds,
> Bob Borger
> Europa XS Tri, Rotax 914, Airmaster C/S Prop.
> Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
> 3705 Lynchburg Dr.
> Corinth, TX 76208-5331
> Cel: 817-992-1117
> rlborger@mac.com
>
> On Nov 4, 2013, at 10:16 PM, Andrew Sarangan <asarangan@gmail.com> wrote:
>
> Looking through the email archives, there seem to be some
> misunderstanding on what the tank is made of. It is polyethylene (PE).
> It is definitely not PTFE (Teflon) or nylon as some had suggested. I
> don't know why polyethylene was chosen, but my guess is it is the
> rotomolding process itself. The majority of rotomolding is done with
> polyethylene so that may have been the most cost-effective choice.
>
> Weather it is LDPE (Low density polyethylene) or HDPE, neither one is
> great with gasoline. Assuming it is LDPE, the attached chart lists it
> as "Limited Compatibility" at 20C and "Not Satisfactory" at 60C.
> Granted, liquids don't heat up quickly, but over a full hot summer
> week, 40C may not be unrealistic. It would be interesting to examine
> if the tank failures have come mostly from warmer climates.
>
> There have also been discussions about inadequate support of the tank
> that could lead to tank failures. This is true, but polyethylene
> should only yield under stress, not crack. Cracking is more indicative
> of a brittle material. My tank has been sitting on the shelf for over
> 12 years and when I was drilling out the bosses this week, it felt
> waxy and ductile, not hard and brittle. So it is not the age of the
> tank that makes it brittle. It is the exposure to gasoline. All of
> this points to the importance of a good barrier coating, and probably
> even more important in hot climates.
>
> I was also told by Fluoroseal that automotive level coating is
> generally not done in Europe. Not knowing the level of coating is the
> main reason I am pursuing a second coating on my tank.
>
>
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