FWIW, just to chime in again, I'd highly recommend that any builders who
either have not yet installed their tank, or have a replacement tank going
into a repair job should take advantage of this treatment opportunity. It
is a pity that the factory did not treat adequately to be compatible with
the nasty North American Mogas.
Pity that only a small percentage of the North American builders are on
this list, as I suspect there are many an off-line builder who would go for
the treatment.
Cheers and blue skies,
Pete
A239 - still a pile of parts :-(
On Mon, Nov 4, 2013 at 11:16 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.
>
>
> On Mon, Nov 4, 2013 at 9:09 PM, Pete <peterz@zutrasoft.com> wrote:
> > I had used the same company to fluorinate my circa 2001 tank to the
> highest "automotive level", and it did indeed come back with a much
> different "frosty" finish. So although I cannot attest to its effectiveness
> as it still :-( does not have fuel in it, the treatment surely did change
> the surface texture, so it must have penetrated more than the reported
> factory treatment. This is the same company that treats automotive fuel
> tanks to meet evaporative emissions standards, as well as at lower levels
> for items such as shampoo bottles etc. I did carefully clean my tank and
> cobra with naphtha, and wrapped and sealed them in poly inside a shipping
> crate to keep them clean and as a result I did not have any "burning"
> issues from the treatment. I followed the company's advise and made *all*
> finish cuts to the openings prior to treatment. To not do so (as per the
> factory tanks) negates the surface treatment as the fuel migrates into the
> material via the untreated cuts and subse!
> > quently swells and suffers long term embrittlement. I had gone it
> alone at the time as I could not find any other takers - hopefully Andrew
> will have better luck. I figured the cost is well worth the high likelihood
> that I will avoid the tank swelling and cracking others have had over the
> long term, with the resultant hacking in of a replacement down the road.
> >
> > I am contemplating piggy-backing on this order to treat a small LDPE
> motorcycle fuel tank I had purchased, but need to first verify with that
> mfg if this tank's "x-linked PE" is compatible. They did not treat their
> tanks as they do not need to meet (off road) emissions std's, but
> experience has shown me that these tanks do smell up a garage.
>
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