Extracting Ethanol

Ernie

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This is my first post and wasn't sure where to place it. I know you can mix water with gas and using something like a Glass Pyriform Separatory Drop Funnel with a Stopcock, you can see the water absorbed ethanol go to the bottom, then whatever amount of water that's left over will be on top of that, and then the gas will be on top of it all. Next you open the stopcock and drain the ethanol absorbed water and remaining water, and you're left with just gas. My question is this... When you extract the ethanol and water, does it extract "anything" else from the gas that should stay in the gas? Any petroleum chemistry people out there?
Now my comment about your forum. I have seen a lot of forums, but I have never seen one with this much information and participation. This is the best of the best! If I may, the only thing I would add is GENERAL Questions, since I wasn't sure where to post. Again, really impressed!!

Thanks,
Ernie
 

Smack

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Ernie, I've been running straight-out-of-the-pump, ethanol-containing fuel in my Rotax 912 for 15 years. No issues.
You're living the anti-ethanol lie; most (all?) of our engines will handle the 10% w/o an issue.
Unless you really just want to go through that process, you can also search for retailers who are selling non-ethanol-containing fuel, but it is lower octane and more expensive.
Brian
 

georgio744

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It is my understanding that the ethanol contributes to the octane rating of the fuel. If the ethanol is removed the octane rating will be something other than what it was originally.
I can't remember exactly where I was told this. It may have been one of the seminars at Airventure.
When I can get it, I try to use Swift Fuel 94 octane ethanol free. Most Of the time, though, I use premium auto gas as does Brian.
George
 

eddie

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Ethanol is an octane booster I have been running 91 octane 10% alcohol for more than 800 hrs in my turbo charged 2.5 Subaru

with great results,I tried to run av-gas but it took out my valves in about 100 hrs.

Also running a high octane fuel in a low compression engine is a waste of money,Octane just allows the engine to run with a higher

compression ratio without self destructing, it doesn't increase performance by its self.

If a turbocharged engine starts predonation (knocking) it will either crack the pistons or turn them into a liquid from the excessive heat.
 

Uncle Willie

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Ethanol has an Octane rating of 108.
Removing the Ethanol from E-10 fuel will lower the Octane Rating by 2 points.
Why would you want to do that?

If you really want E-0 fuel just go to your local marina.
There are old boats that need E-0 Fuel because their engines are 50 years old and the hoses and tanks are not compatible with Ethanol.
Expect to pay Marina Fuel Prices which are similar to Airport fuel prices. $$$

If your engine and fuel system parts are less than 20 years old, E-10 is just fine.
There are dozens of Anit-Ethanol Myths that are easily proven False.
What is your real concern?
 

eddie

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The only real downside of ethanol is that it will absorb moisture,but in the NM desert where I live that's not an issue.

And of course it burns a little cooler than gasoline.(A little less bang for the buck).
 

rcflier

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Recently I've been reading the CPS articles "Care and Feeding" (again). And the author is not happy with the ethanol rich gasoline for Rotax two strokes.

Would anyone like to comment on that? In Denmark the gasoline has to contain 5% ethanol by law. That might be an average value for a company,

so some products have less and others have more...

The author also recommends a semi-synthetic blended oil to mix with the gasoline.

Cheers
Erik
 

fara

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There are other downsides of ethanol for aircraft. It can cause vapor lock easier.
The other problem is formulations of car gas. Winter formulations in the US are specially bad and can cause vapor lock really really easily if the ambient temps are above 75 F. There are 20 different formulations of fuel in auto world in the US.
The best of our engines are non-leaded Avgas like Swift. BP is supposed to be coming out with their non-leaded av gas as well

https://www.popularmechanics.com/ca...blend-gasoline-whats-the-difference-13747431/
 

Eric S

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Smack;n1139196 said:
Ernie, I've been running straight-out-of-the-pump, ethanol-containing fuel in my Rotax 912 for 15 years. No issues.
You're living the anti-ethanol lie; most (all?) of our engines will handle the 10% w/o an issue.
Unless you really just want to go through that process, you can also search for retailers who are selling non-ethanol-containing fuel, but it is lower octane and more expensive.
Brian
Same here, one 912 and two 582s, EXCEPT, on my aerobatic plane with a third 582 which has fiberglass fuel tanks. I run Avgas only in that one since we still can't buy ethanol free nearby in central Texas. Ethanol will deteriorate fiberglass over time.
 

Uncle Willie

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eddie;n1139204 said:
The only real downside of ethanol is that it will absorb moisture, but in the NM desert where I live, that's not an issue.

And of course, it burns a little cooler than gasoline. (A little less bang for the buck).
The Plus Side is that Ethanol Absorbs Moisture!

If you pour 10 ounces of water into a 20-gallon tank of E-0 fuel you will have 10 ounces of water sitting on the bottom of the tank.
If you pour the same 10 ounces into the same tank of E-10 you will have no water at the bottom of the tank to get sucked into the engine causing problems.
The water will get just dissolve into the fuel and when atomized and mixed with the combustion air, just raises the humidity slightly.

One gallon of E-10 gas can absorb about 0.6 ounces of water. (12.8oz per 20gal.)
One gallon of Gasoline Requires 91 lbs (1200 cu-ft) of air to burn.
1200 cu-ft of 50% humidity 70°F Air contains a hair more than one ounce of water.
Adding the 0.6oz of water from our worst-case fuel raises the humidity to about 80%.
Flying through a cloud would be worse, but just as harmless.

Ethanol does not contain any "Pheremones " that magically attract water from the Air.
If you have water in your fuel tanks, it came in as (Rain, Wash) water.

20 gallons of gas would have to extract every last drop of water from 720 cu-ft (5400 gal) of our 50% air before it reached saturation.
Unless you are venting your tank with a fan it isn't going to happen.
And even then it isn't going to happen, The physics of vapor equilibrium will prevent it.

The numbers just do not work.

Burning cooler is what promotes the lower emissions pollution.
You will get lower miles per gallon, that part is true, but you may also get higher Miles for your "Buck" depending on the prices of the fuels.

It is just alcohol, it is not Alien Blood!
 

eddie

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Bill ,thanks for the info good to know.
 

PW_Plack

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Concerns about ethanol are not a "lie," but they may be exaggerated. The two big downsides are degradation of fuel system materials, and phase separation.

In cars, where tanks of fuel are used and refilled often, it's not a big deal. But for boats or aircraft which may sit for long periods in areas of high humidity, it's more concerning.

Every time a partially-filled fuel tank goes through a day/night cycle of temperature and humidity, it can get condensation on the walls of the fuel tank. In a tank of straight gasoline, those droplets sink to the bottom of the tank, where they're trapped as liquid, because water is heavier than gasoline. As this goes on night after night, the total volume of humid air passing through the tank adds up.

Aircraft with fuel sumps have a way to check for and get rid of this accumulated water, although dumping a little test tube of fuel on the tarmac every time you do a pre-flight has become politically incorrect.

Fuel with ethanol will absorb the water, which can't be drained using a sump. If you are climbing out after your first takeoff in months, and the temperature drops as you climb, there's a chance the alcohol/water mix will reach the critical concentration at which phase separation occurs, allowing water to suddenly separate from the fuel and sink to the bottom of the tank. This concern is why certified aviation fuels do not contain ethanol. How big a deal is it for those of us who don't climb into cold temperatures frequently? Who knows.

A lesser issue is the lower energy content in the ethanol. E10 running in an engine set up for gasoline will make less power and cost you 5% or more in range.

Many areas have gas stations which sell 88 octane ethanol-free (E0) fuel. It's more widely available in the winter, when snowmobilers use bunches of it. I'm fortunate to have a station nearby which sells 91 octane E0 UL year-round, for prices about 15% above E10. I fill my fuel cans there on the way to the airport. The difference in cost and slight reduction in convenience is a sacrifice I make in the interest of peace of mind.
 

Uncle Willie

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I agree with the exaggeration statement. The anti-Ethanol factions take partial facts and twist them into apparent truths.

The water Myth...
A half filled 20-gallon tank of ethanol fuel represent a considerable thermal mass.
It will remain warmer than the surrounding air.
The evaporating fuel will tend to push vapors out of the fuel tank preventing air infusion into the tank.
Minimal air will diffuse into the tank.
Gasoline vapors are heavier than air, so the air will tend to float on top of the fuel vapors and be the first gas to get pushed out of the vent during the warming cycle.
The vapor filled upper areas on the inside of the tank may promote water condensation (Sweat!) on the Outside of the tank but not on the inside.

Let's consider a worse case temperature fluctuation.
Assuming a 20-gallon tank half filled with 10 gallons of fuel, and 10 gallons of vapor.
In order to get the tank to breath 1 gallon worth of air each day the temperature would need to vary by 10% cyclically. 10% of the 10 gallons.
That 10% is in absolute values. Room temperature is about 300°K (27°C) (80°F)
A 10% change would be 30°K (30°C) (54°F)

This would mean the temperature swing of the tank and fuel would need to be more than 30°C/54°F to move 1 gallon worth of humid air into and out of the tank every day.
30°C/54°F is an unreasonable amount of temperature swing to occur on a daily basis anywhere in the world. But let us assume it could happen.

Remembering from post #10 that 20 gallons of fuel would need to condense all the water out of 5400 gallons of 50% humidity air to become saturated.
This means we will need to condense out every drop of the water from 2700 gallons of our 50% humidity air to saturate our 10 gallons of fuel in the tank.
At 1 gallon per day, it will take 2700 days (7.4 years) of perfect conditions every day to start phase separation. 80° days, 26° Nights!
If we hangared the plane in a 100% humidity sauna and cycled the temperature daily, we could do it in under 4 years.

I have ongoing experiments myth-busting Ethanol.
I have a liter jar initially filled with 800cc of E-10 auto gas.
It has a short vent tube simulating a fuel tank vent attached through the lid.
It has been sitting on a shelf in an unheated detached garage since 2012.
After 6 winters and summers, 28% of the fuel has evaporated. The lid is showing some rust.
The fuel is noticeable brownish and smells a bit like turpentine.
The one thing that is not showing is any water.
Not a hint of cloudiness. No phase separation. No Water.
The Fuel is Old and Varnished but it is not waterlogged.
OldFuel.jpg

Another jar, only 10% full, has evaporated 50% of its initial fuel.
It also shows no water.

If you have water in your tank, it came in as liquid water, Not Vapor.


The Phase separation Myth...
10 gallons of E-10 fuel contains about 1 gallon of Ethanol.
10 gallons will support about 6.4 ounces of water in suspension.
If you were to add an additional 2 ounces of water you would get the 2 ounces of water at the bottom of the tank along with a few ounces of ethanol.
You would not have all 8 ounces of water and the entire gallon os of alcohol phase separate like an avalanche.

And contrary to popular thinking, phase separation is not an irreversible process.
Adding another 5 gallons of fresh fuel to the tank would cause all the phase separated Water/Ethanol to go back into suspension.
This is easily demonstrated at home with a jar of fuel and some water.

Take half a jar of gas.
Drip in water, stirring as you go.
Once it turns cloudy and phase separates...
Add some more gas to the jar...
Clear gas again!

Worried about phase separation?
Top off your tank with fresh gasoline just before the flight.

Water in your tank from rain or condensation is the same issues whether you use E10 or E0.
It is still water in the fuel.
With E0 you will have water you need to drain.
With E10 you will never see it unless it is excessive.
 

eutrophicated1

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The expression "burns hotter" or "cooler" doesn't add up to me. What matters really is the number of BTU's the fuel releases upon combustion. Hydrogen burns at a higher temp than gasoline; yet supplies significantly fewer BTU's.
 

eutrophicated1

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"And even then it isn't going to happen, The physics of vapor equilibrium will prevent it."
So, Willie, are you assuming the composition of fuel tanks to have no effect on daily thermal cycle water condensation? Tanks constructed of aluminum will definitely cool down or heat up their contents much more rapidly than those made from polymers. Also, gasolines typically include 40 or so different aliphatic hydrocarbon, as well as 10 different carbon ring compounds. Have you taken into account all the various partial pressures these provide? How are these partial pressures changed over time as the ones with higher partial vapor pressures are evaporated?

Please explain: "Burning cooler is what promotes the lower emissions pollution."
This generalization presupposes lowering the combustion output of 10-20 different pollutant compounds, 5 of which are various oxides of nitrogen that are produced at lower combustion temperatures.

"One gallon of Gasoline Requires 91 lbs (1200 cu-ft) of air to burn." Are you assuming an 'adiabatic' combustion event? At the approximate 5000 rpm range of the average gyro engine, adiabatic combustion is to all intents and purposes, impossible.

I believe there are way too many assumptions and generalizations going on in this thread to constitute a definitive discussion.
 

Kolibri

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A very helpful post, thanks Paul.
 

Uncle Willie

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eutrophicated1;n1139248 said:
"And even then it isn't going to happen, The physics of vapor equilibrium will prevent it."
So, Willie, are you assuming the composition of fuel tanks to have no effect on daily thermal cycle water condensation? Tanks constructed of aluminum will definitely cool down or heat up their contents much more rapidly than those made from polymers.
The thermal mass of the fuel inside of the tank will have the major control of the temperature of the vapors inside of the tank.
Aluminum or Poly tanks will cool much differently if subjected to a sudden change in temperature.
Most aircraft are hangared so see little day/night temperature changes.
Whether on the ramp or in the hanger those changes take place slowly over the course of hours.
A 5-gallon poly gas can and a metal can are not going to show much temperature difference if the temperature changes 20 degrees over an 8 hour period.

If you were to bring both ice cold cans into a harm room. The would both "Sweat Water" all over their outer surfaces.
If they were both tightly sealed you would see both of them expand as they warmed up, indicating that the pressure inside the cans was higher than the pressure in the room.
Open the vents and the fuel vapor would rush Out. The cans will be dripping wet but No Air or Water Vapor is going In.

Also, gasoline typically includes 40 or so different aliphatic hydrocarbon, as well as 10 different carbon ring compounds. Have you taken into account all the various partial pressures these provide? How are these partial pressures changed over time as the ones with higher partial vapor pressures are evaporated?
I specifically ignored all the partial pressures and the evaporation because if you consider that the fuel is evaporating and flowing Out the vent, there is no longer any path for the Air with its deaded water getting in. This just extends the time to to get enough water vapor into the tank to cause trouble from 7 years to multiple decades.

"One gallon of Gasoline Requires 91 lbs (1200 cu-ft) of air to burn." Are you assuming an 'adiabatic' combustion event? At the approximate 5000 rpm range of the average gyro engine, adiabatic combustion is to all intents and purposes, impossible.
You are missing the point. The1200cu-ft reference just puts a reasonable number on the approximate amount of air involved.
If you want to go 30% Rich or Lean and use 800 or 1600 cu-ft. The result is the same.
Flying through a cloud with 100% humidity is still worse than 0.5% of water dissolved in the fuel, and still just as harmless.

I believe there are way too many assumptions and generalizations going on in this thread to constitute a definitive discussion.
That may be true, but it is all we have to work with. :sad:

An ounce of Water dissolved in the Fuel is a far better choice than an ounce of liquid water getting sucked into a carburetor.

The engine does not have the issues with the ethanol.
The issue is in older planes with fuel system components like Fiberglass and older rubber compounds that are not tolerant of the solvent.

P.S.
I don't think you are allowed to use the term "BTU" without risking the loss of your self-appointed Designation. :smile:
 

Doug Riley

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Bill, your analysis arguing against the "fuel-tank-as-dehumidifier" theory (and the jar experiment) are convincing.

My experience, however is that, for whatever reason, considerable water used to accumulate in the 15-gallon fuel system of my Dominator over a Vermont winter. It sat in an unheated garage. The two seat tanks were polyethylene. Winter temps 'round here fluctuate wildly between -25 F and +60 F or more. An open-air craft is likely to sit unused for at least 12 weeks. I found ounces of water in the bottom of the system. It was enough to rust the plated steel hose barbs and valves at the bottom of the system. I tasted a drop to verify that it was H20.
 

Smack

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We used to inject water (into the intake manifold) on the Reno race plane a few years back. Allowed us to run a bit more advance on the timing and the correct (not excess rich) fuel ratio for best power. The added water (later water/methanol) cooled the cylinder a bit when WOT (oops, sorry, another TLA...). I'd say that is similar to 'water in the fuel', but maybe a bit more metered/controlled.
Brian
 

eutrophicated1

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Doug Riley;n1139308 said:
Bill, your analysis arguing against the "fuel-tank-as-dehumidifier" theory (and the jar experiment) are convincing.

My experience, however is that, for whatever reason, considerable water used to accumulate in the 15-gallon fuel system of my Dominator over a Vermont winter. It sat in an unheated garage. The two seat tanks were polyethylene. Winter temps 'round here fluctuate wildly between -25 F and +60 F or more. An open-air craft is likely to sit unused for at least 12 weeks. I found ounces of water in the bottom of the system. It was enough to rust the plated steel hose barbs and valves at the bottom of the system. I tasted a drop to verify that it was H20.
I whole heartedly agree with you, Doug. Seasonal local weather conditions can have a large effect on vented gas containers left outside, or in unheated buildings. I live in the midwest, that is: between the Smokey and Rocky mountain chains. Buck Perry, of Hickory, NC, master angler and college professor called this area "cold-front-alley". Cold-fronts come through here in Michigan about every 1.5 days on average. Its not unusual for temps to vary 25-30 degrees day-to-night, and day-to-day. Ambient "relative" humidity can vary from 20% to 100% in 12 hours. Along with cold-fronts come significant variations in atmospheric pressure. Moreover, seasonal temperature variations can run from -20 to +100 degrees Fahrenheit. I've seen temps change from 75 degrees one day, to -20 the next. But that only happens once every 5 years or so. As an all-season angler, I pay close attention to the changes in local weather. I've had 20 pound Liquid Petroleum tanks exhibit ambient pressures of only 2 pounds per square inch.

By the way, Doug, is it possible that the water you found in your gas had been 'stirred' into it, and then separated out when stored in non-agitated containers? I totally believe you found water in your tanks.

As I've stated earlier in this thread, gasoline is a mixture of at least 30 different organic compounds, the ambient partial pressures of which can vary enough to skew vented container contents through evaporation and condensation. When ambient temperatures vary 20-40 degrees in successive 12 hour periods, vented containers can literally suck in, as well as blow out various gases of partial pressure, including water vapor. Which ones and how much needs to be measured in 'controlled' experiments in a dozen or so climate locals around the country. I'm guessing the petroleum company chemists have already done all of this, maybe even published.
 
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