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bruce.anthony(at)holidayc
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 Posted: Mon Nov 26, 2007 9:46 am Post subject: Removing Ethanol from you car-gas |
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Well, here's why it's not a good idea to fiddle with this. First,
Ethanol is easily blended in gasoline from one to 99 % and blending
ethanol straight from the plant is cut with 5% natural gasoline so it's
not drinkable - taxes, you know. It's not complicated - we do it in our
tanker trucks at the gasoline terminal - and it doesn't require exotic
chemicals or methods. The ethanol/gasoline mixture is very stable
unless water is added to the mix. If water shows up, ethanol in the
blend will initially absorb the water (which might be a good thing in a
fuel tank as it prevents immediate engine misfire or stalling from the
water that would immediately form a separate phase in a tank of straight
gasoline). As more water is added a separate phase of water, ethanol,
and gasoline will form in a concentration that can only be predicted
from a trinary phase diagram. This separation does not require low
temperatures or lots of water, although both of these characteristics
have an impact on the amount and how soon the phase will form. This
separated phase will not burn properly in internal combustion engines.
Keep water away from ethanol blended gasoline including keeping your
tanks either full or completely empty if your plane sits around all
winter.
The separated ethanol/water/gasoline phase has the federal
characteristics of a hazardous waste, the disposal of which is regulated
by law and is quite expensive. The cost of disposal alone would render
any attempt to separate out the ethanol as not cost effective.
My NIOSH pocket guide tells me that at standard conditions, ethanol has
a boiling point of 173 degrees F and gasoline's B.P. is 102 degrees F
(gasoline is a mixture so the lighter components will boil off first).
Ethanol also has a lower vapor pressure than the lighter gasoline
components. Consequently, ethanol itself is less likely than gasoline
to cause vapor lock issues. Oftentimes, chemical mixtures behave
differently than pure components, but I haven't noticed any problems
with vapor lock in tuned cars in hot Minnesota summers.
Ethanol is more corrosive to aluminum than gasoline, but in a 10 percent
ethanol blend this is likely not significant. We've been selling E-85
(65% to 85% ethanol in gasoline) for nearly 10 years now and our
original dispensers, which have some aluminum components, still seem to
be OK. Time will tell.
As a previous poster wrote, ethanol is added to gasoline to provide more
oxygen to the combustion process in an engine and thus lower emissions.
While E-85 has an octane rating of up to 110, the octane improvement
from 10% ethanol in regular gasoline is only about 3 points.
Although it might not be best suited for aviation purposes (then again
it might be fine), in my opinion a 10% ethanol in gasoline blend has an
unjustified bad rap in some quarters that is not justified by the
experience in automobiles. Time, experience, and the engine
manufacturers will have the final say in airplanes.
To those amateurs who would try distilling pure ethanol from your phase
separation, have your survivors tell us how that worked out.
Bruce Anthony
Chemical Engineer
RV-9 Builder
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tracy(at)rotaryaviation.c
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| Posted: Mon Nov 26, 2007 2:23 pm Post subject: Removing Ethanol from you car-gas |
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Thanks for "separating the wheat from the chaff" Bruce. Amazing the amount of it (chaff) that comes across the internet.
Tracy Crook (burned a bit of the 10% stuff in my Rotary powered RV-4 - no ill effects)
On Nov 26, 2007 12:34 PM, Bruce Anthony <bruce.anthony(at)holidaycompanies.com (bruce.anthony(at)holidaycompanies.com)> wrote:
[quote]--> RV-List message posted by: "Bruce Anthony" < bruce.anthony(at)holidaycompanies.com (bruce.anthony(at)holidaycompanies.com)>
Well, here's why it's not a good idea to fiddle with this. First,
Ethanol is easily blended in gasoline from one to 99 % and blending
ethanol straight from the plant is cut with 5% natural gasoline so it's
not drinkable - taxes, you know. It's not complicated - we do it in our
tanker trucks at the gasoline terminal - and it doesn't require exotic
chemicals or methods. The ethanol/gasoline mixture is very stable
unless water is added to the mix. If water shows up, ethanol in the
blend will initially absorb the water (which might be a good thing in a
fuel tank as it prevents immediate engine misfire or stalling from the
water that would immediately form a separate phase in a tank of straight
gasoline). As more water is added a separate phase of water, ethanol,
and gasoline will form in a concentration that can only be predicted
from a trinary phase diagram. This separation does not require low
temperatures or lots of water, although both of these characteristics
have an impact on the amount and how soon the phase will form. This
separated phase will not burn properly in internal combustion engines.
Keep water away from ethanol blended gasoline including keeping your
tanks either full or completely empty if your plane sits around all
winter.
The separated ethanol/water/gasoline phase has the federal
characteristics of a hazardous waste, the disposal of which is regulated
by law and is quite expensive. The cost of disposal alone would render
any attempt to separate out the ethanol as not cost effective.
My NIOSH pocket guide tells me that at standard conditions, ethanol has
a boiling point of 173 degrees F and gasoline's B.P. is 102 degrees F
(gasoline is a mixture so the lighter components will boil off first).
Ethanol also has a lower vapor pressure than the lighter gasoline
components. Consequently, ethanol itself is less likely than gasoline
to cause vapor lock issues. Oftentimes, chemical mixtures behave
differently than pure components, but I haven't noticed any problems
with vapor lock in tuned cars in hot Minnesota summers.
Ethanol is more corrosive to aluminum than gasoline, but in a 10 percent
ethanol blend this is likely not significant. We've been selling E-85
(65% to 85% ethanol in gasoline) for nearly 10 years now and our
original dispensers, which have some aluminum components, still seem to
be OK. Time will tell.
As a previous poster wrote, ethanol is added to gasoline to provide more
oxygen to the combustion process in an engine and thus lower emissions.
While E-85 has an octane rating of up to 110, the octane improvement
from 10% ethanol in regular gasoline is only about 3 points.
Although it might not be best suited for aviation purposes (then again
it might be fine), in my opinion a 10% ethanol in gasoline blend has an
unjustified bad rap in some quarters that is not justified by the
experience in automobiles. Time, experience, and the engine
manufacturers will have the final say in airplanes.
[b]
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