Water/Avgas/Gasahol/Mogas

Jim Weir wrote:

snip
Yes, I know that alcohol left sitting in gasoline will slowly accumulate
water
from condensation and such, and is a variable.

It will probably accumulate quite quickly from the hose the retailer sticks
in the tank to sell water at a high price.

regards

jc

LEGAL - I don't believe what I wrote and neither should you. Sobriety and/or
sanity of the author is not guaranteed

EMAIL - and are not valid email
addresses. news2x at perentie is valid for a while.

Jim -

I wrote an article on winter operation that was published in the Dec
1986 issue of Sport Aviation. In it I posted a chart of the approx
max dissolved water in PPM in aromatics and non-aromatic fuels. It
was based on some sketchy data I got from Amoco.

The amount of dissolved water increases with temperature. The point
that I was trying to make in the article was that severe chilling will
cause some of the water to precipitate out of solution as snow, which
can quickly and effectively clog the fuel screens.

It happened to me.

Niel Petersen

On 15 Aug 2004 21:50:37 -0700, ) wrote:

Jim -

I wrote an article on winter operation that was published in the Dec
1986 issue of Sport Aviation. In it I posted a chart of the approx
max dissolved water in PPM in aromatics and non-aromatic fuels. It
was based on some sketchy data I got from Amoco.

The amount of dissolved water increases with temperature. The point
that I was trying to make in the article was that severe chilling will
cause some of the water to precipitate out of solution as snow, which
can quickly and effectively clog the fuel screens.


Now if you used mogas with 10% Alcohol that wouldn't be a problem. Of
course there are a few inconvenient side effects from the Alcohol.

It seems to me if they can make the car engines stand up (more
specifically the gaskets and O-rings) then they could do the same in
aircraft systems.

Which brings to mind the question: How does anyone in Michigan use a
Mogas STC? Our gas is not labeled as to whether it contains Alcohol
or not. The pump sticker only states, "Meets Michigan fuel standard
(something or other) call this 800 number for specifics or
complaints", or something to that effect.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
It happened to me.

Niel Petersen

Two years of college chemistry does not a chemist make out of me, so let's see
if anybody has the answer to this one:

Until we get around to making gaskets and o-rings that will stand up to alcohol,
is there a cheap and easy way to chemically (or mechanically) take the alcohol
out of gasoline? Yeah, I know that we could use fractional distillation, but
that's a little beyond the average home kitty-litter filter process that I was
contemplating.

Thoughts?

Jim



Roger Halstead
shared these priceless pearls of wisdom:

-
-It seems to me if they can make the car engines stand up (more
-specifically the gaskets and O-rings) then they could do the same in
-aircraft systems.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

"Jim Weir" wrote in message
...
Two years of college chemistry does not a chemist make out of me, so let's
see
if anybody has the answer to this one:

Until we get around to making gaskets and o-rings that will stand up to
alcohol,
is there a cheap and easy way to chemically (or mechanically) take the
alcohol
out of gasoline? Yeah, I know that we could use fractional distillation,
but
that's a little beyond the average home kitty-litter filter process that I
was
contemplating.

Thoughts?

If you figure out a way, don't let Slusarczyk in on it. He'll want to put
some in the muzzleloader to dilute it.

Rich S.

"Jim Weir" wrote:
Two years of college chemistry does not a chemist make out of me, so let's
see
if anybody has the answer to this one:

Until we get around to making gaskets and o-rings that will stand up to
alcohol,
is there a cheap and easy way to chemically (or mechanically) take the
alcohol
out of gasoline? Yeah, I know that we could use fractional distillation,
but
that's a little beyond the average home kitty-litter filter process that I
was
contemplating.

Thoughts?

I guess you're thinking of something like SilcaGel (which has a high
affinity for water), but in this case we need a substance that has a high
affinity for ethanol but none for the hydrocarbons. Sounds like you need an
Irish liver. :-)

No, seriously, you might be able to use some of the laboratory-grade
semi-permiable membranes, if you can find one that passes ethanol-sized
molecules but not aromatic hydrocarbon-sized ones.

Russell Kent

How about using the differential solubility in water? Add water, shake to
dissolve the alochol in the water, allow to seperate, pour off the gasoline.
Lather, rinse, repeat.

Dave

Russell Kent wrote:
"Jim Weir" wrote:

Two years of college chemistry does not a chemist make out of me, so let's

see

if anybody has the answer to this one:

Until we get around to making gaskets and o-rings that will stand up to

alcohol,

is there a cheap and easy way to chemically (or mechanically) take the

alcohol

out of gasoline? Yeah, I know that we could use fractional distillation,

but

that's a little beyond the average home kitty-litter filter process that I

was

contemplating.

Thoughts?


I guess you're thinking of something like SilcaGel (which has a high
affinity for water), but in this case we need a substance that has a high
affinity for ethanol but none for the hydrocarbons. Sounds like you need an
Irish liver. :-)

No, seriously, you might be able to use some of the laboratory-grade
semi-permiable membranes, if you can find one that passes ethanol-sized
molecules but not aromatic hydrocarbon-sized ones.

Russell Kent




--
Dave Butler, software engineer 919-392-4367

Jim -

Yes, you can remove alcohol from a gasahol mixture, but in so doing
you will have a remaining all-hydrocarbon fuel that has substantially
less antiknock capability - lower octane. I don't know how much the
octane reduction is but I suspect what you have left would be marginal
even in a lawnmower.

But to separate the mixture, simply mix the gasahol aggressively for
several minutes with a substantial volume of water, then allow the mix
to settle. This will allow the water to remove most of the alcohol
from the mixture so that only the hydrocarbon component is left. The
water at the bottom will now have the alcohol in solution.

Yes, gasahol has eliminated gas line freezeup problems. But no way
would I want to put it in an aircraft.

You can test for alcohol in a fuel sample by mixing about 10 parts
sample with 1 part of water, shaking the mixture for a minute, let it
settle, and see if the apparent volume of the water has increased. If
it has, you had alcohol in the original sample.

I check each car-filling-station load of fuel I buy in Wisconsin,
where gasahol is not mandated. The station dealer is aware of our
aircraft use, but of course he is somewhat in the dark with the
regulatory climate so we can't really depend on him. Otherwise I try
to buy fuel from an FBO that supposedly has a certified load of Mogas.
A few filling stations in Minnesota, where gasahol is otherwise
mandated, and marinas will have a pump of straight gasoline for "old
engines" etc on the side somewhere.

Gasahol can work in a processor controlled car engine that has a
closed loop system to control spark timing and mixture. An engine
properly operating on gasahol will only produce about 95% of the power
output of a hydrocarbon fueled engine. Non processor controlled car
engines just run a little feebler, although the powers that be say
they will emit less bad stuff. There is controversy on this.

Airplane engines have no processor, and even if they did, giving up
another 5% of the takeoff power would be out of the question for a
certificated aircraft. Maybe with a reduction in allowable gross
weight? But what about the reduction in octane? Still lower
compression? Ugh! It doesn't make for a good solution.

At any rate, aircraft fuel systems have not been made tolerant of
alcohol laced fuels probably because there are so many other technical
and legal obstacles to their successful use.

The problem isn't the gaskets and o-rings. The real problem is alcohol is a
weak organic acid and corrodes metals.


"Jim Weir" wrote in message
...
Two years of college chemistry does not a chemist make out of me, so let's
see
if anybody has the answer to this one:

Until we get around to making gaskets and o-rings that will stand up to
alcohol,
is there a cheap and easy way to chemically (or mechanically) take the
alcohol
out of gasoline? Yeah, I know that we could use fractional distillation,
but
that's a little beyond the average home kitty-litter filter process that I
was
contemplating.

Thoughts?

Jim



Roger Halstead
shared these priceless pearls of wisdom:

-
-It seems to me if they can make the car engines stand up (more
-specifically the gaskets and O-rings) then they could do the same in
-aircraft systems.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Jim Weir wrote
Two years of college chemistry does not a chemist make out of me

You're not asking a chemistry question, you're asking a chemical
engineering question. Not the same thing at all. Anyway, I happen to
be one.

is there a cheap and easy way to chemically (or mechanically) take the alcohol
out of gasoline?

Yes. Extraction. Mix gasoline with equal quantity of water, agitate
(shake or stir), let sit in cool place. The alcohol will (almost) all
be in the water phase on the bottom. Drain water off bottom.
Gasoline is ready to use.

Your problem is the water. It now has a few percent alcohol, and
traces of organics from the gasoline. Can't just toss it (legally).

You need to flash off the alcohol and organics. Fill jug with the
water, stopper it but let a tube come out. Warm to 180F, give or
take. This will drive off some gases, which you can feed into a small
flame (a candle will do). When the water level goes down a few
percent, you're good. You can reuse that water for the next batch.

Michael