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1. 03:22 PM - Re: FUEL TANK SEALANTS (FLYaDIVE)
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| Subject: | Re: FUEL TANK SEALANTS |
Hello Pete:
Thank you for taking the time to write up this information.
Aviation and even the automotive industry is in for a long up hill battle
when it comes to gas containing ethanol. There is a move afoot to INCREASE
the ethanol from 10% to 15%. This is going to be very disastrous as new
cars (2011) have right in the operations manual: NOT APPROVED FOR 15%
ETHANOL.
I work with the GA type engines, Lycoming and Continental all the time. Th
e
black coating you mention, I have seen, it forms with either Av or MoGas.
The cause has always been of two reasons:
1 - Blow-By past the piston rings or
2 - Warn Valve guides. Or both.
The amount and hardness also seems (can't verify - not enough proof) to be
because of the type of oil used. Those with high concentrations of
synthetic seem to produce a dryer, harder buildup. And those with a 50:50
blend or no synthetic produce a oily COKE deposit.
Your information about Detroit's fuel is quite, or should be quite earth
shaking. It is understandable to see ethanol or even methanol in gas. I'l
l
even accept TAME or ETBE, but MTBE? That stuff has been mandated to be
REMOVED from gas for at least the past four years. There should not be any
in the USA, unless the produces want a HUGE law suit. Why
would acetone, toluene or MEK be added to gas? There are no reasons to do
such a thing, the refining cost of those compounds is much higher than that
of gas. Sounds like a garage mechanic was using a disposal barrel and
transfered its contents to a fuel tank.
Alcohols (ethanol & methanol) are hygroscopic, they adsorb the water. The
water does not adsorb the alcohols. To increase the concentration of
alcohol you would have to decrease the amount of gas, or decrease the amoun
t
of water. Increasing the amount of water beyond the saturation point of th
e
alcohol would keep the alcohol in suspension up to the 100% point and if
excess water was introduced into the gas... Water being heavier than gas or
alcohol would sink to the bottom. Caring the alcohol with it. But, you can
not get more saturation of alcohol to the bottom of the tank than the
alcohol to water ration.
I keep talking about % of saturation and ratio. Let me elaborate a little.
If the gas has 10% alcohol and you have 10 gallons of gas then 1 gallon of
the mixture is alcohol. Ergo the ratio is 9 parts Gas and 1 part Water.
If you want to remove the alcohol from the gas ADD 10% - (The same
percentage of alcohol or slightly more.) Of water to the gas. The
hygroscopic action of the alcohol will adsorb the water and ... Water being
heavier than gas or alcohol will migrate to the bottom of the tank to be
drained off.
Sorry for repeating what has been addressed before. I mentioned this
because I had a couple of How To and To What Success inquiries.
I did get a lot of responses from the group to my query and THANK YOU gang.
There is only one product that I have not tried as yet. I will bite the
bullet one more time and try that one out. The investment will be only
about $27 so why not!
Barry
On Wed, Jan 12, 2011 at 1:06 PM, Pete Krotje <pete@usjabiru.com> wrote:
> This will be long so please bear with me,
>
>
> The question of solvents in auto gas is a good bit more involved than jus
t
> ethanol. We=92ve recently had customers with fiberglass tanks and others
with
> poly tanks who have had problems with auto gas even with no ethanol. In
> some cases the auto gas has dissolved the tank sealant even though the
> sealant is supposed to be ethanol resistant. In other cases the auto gas
> has reacted with something to form stringy mucus like strands that are qu
ite
> good a gumming up the carb slide. In two other cases something in auto g
as
> coated the inside of the engine with a black combustion product that look
ed
> much like burned carmelized sugar (coated valves and valve guides resulti
ng
> in stuck valves) At this point Jabiru USA is unable to pinpoint the cause
of
> the fuel anomalies.
>
>
> We have been investigating what may cause tank sealants to dissolve and
> have been surprised at what we have found. Anyone can find the same info
if
> you dig hard enough and pursue the initial Google findings. A week spent
> digging and following various leads will result in dozens of reports on a
uto
> gas quality issues. We have seen reports detailing contaminants in fuel
> found in the Detroit area that included ethanol, methanol, MEK, acetone,
> toluene, TAME and MTBE. Tank sealants are not designed to stand up to ma
ny
> of those contaminants.
>
>
> Additionally, many tank sealants are labeled as resistant to 10% or 15%
> ethanol concentrations. If the gas ' ethanol mix stays blended the
> concentrations may stay below those limits. However ' when some
> condensation enters the tank the resulting moisture combines with ethanol
> very readily (ethanol will combine with water much faster or more easily
> than with gasoline). At some point the water ethanol mixture becomes
> heavier than gas and sinks to the bottom of the tank where it may remain
> with the ethanol concentration higher than 15%. This concentration excee
ds
> the tolerance of many tank sealants and can dissolve the sealant. Since
> aircraft are prone to sitting for longer periods than cars, the ethanol m
ix
> at the bottom of the tank can be undisturbed sometimes for weeks or even
> months at t time while dissolving the sealant.
>
>
> Again, We are not even close to having many answers but offer these
> observations on what we=92ve seen from auto gas use over the last 12 year
s.
> We really have not been able to come to any solid conclusions other than
to
> think about installing welded aluminum tanks (not an option for many
> planes).
>
>
> On the other hand ' we=92ve yet to see a tank problem with the sealants
we
> use when the aircraft is flown exclusively on avgas 100LL. It costs a bi
t
> more but we view it as cheap insurance for our planes with tanks sealed w
ith
> any of the commercial sealants out there today.
>
>
> Pete Krotje
>
> Jabiru USA Sport Aircraft, LLC
>
> 931-680-2800
>
> www.usjabiru.com
>
>
> *From:* owner-jabiruengine-list-server@matronics.com [mailto:
> owner-jabiruengine-list-server@matronics.com] *On Behalf Of *FLYaDIVE
> *Sent:* Wednesday, January 12, 2011 11:04 AM
> *To:* jabiruengine-list@matronics.com
> *Subject:* JabiruEngine-List: FUEL TANK SEALANTS
>
>
> Hello Gaggle:
>
>
> I have been fighting leaking fuel tans for a while. The tanks are alumin
um
> and sealed with PRO SEAL or the equivalent.
>
> Since my engine likes both AvGas and MoGas and MoGas has ethanol I would
> like a sealant that can stand up to both.
>
> Stop - I know about the trick of removing the ethanol from MoGas but that
> is only about 90% effective.
>
> I would like to run straight MoGas.
>
> Would anyone out there have any experience in this area?
>
>
> Thank you for the assistance.
>
>
> Barry
>
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