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Testing the Testing of Mogas



 
 
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  #1  
Old July 20th 06, 04:52 AM posted to rec.aviation.piloting
Jay Honeck
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Posts: 3,573
Default Testing the Testing of Mogas

Plop-plop, fizz-fizz... :-)

In a previous thread I outlined the new (vastly more convenient)
"alka-seltzer method" of testing your mogas for both ethanol and water
-- but (for those who missed it) here it is again:

1. Tap a few ounces of suspect gas into a cup
2. Drop 1/4 of an alka-seltzer into the gas
3. If no fizz, no alcohol or water is present, and the gas is "good"

The question was/is: Is it chemically valid to expect alka-seltzer to
fizz in the presence of alcohol?

Mary (with her minor in chemistry) and I (with my English degree that
allows me to, er, write about this) devised the following empirical
test:

Part I:

1. Purchase a bottle of 95% pure isopropyl (rubbing) alcohol. While
it's not ethanol, Mary determined that the chemical make-up is similar
enough for this test.

2. Pour a few ounces into a cup.

3. Add 1/4 tablet alka-seltzer to the alchohol.

4. Observe results.

** Sure enough, the tablet instantly starting fizzing.**

Part II:

1. Go to gas station we always buy our gas from.

2. Pump a few ounces into a cup.

3. Add 1/4 tablet alka-seltzer to the cup.

4. Observe results.

** Sure enough, the tablet just sat there -- no fizz.**

Part III:

1. Add some alchohol to aforementioned cup of gas, approximating a 10%
mixture.

2. Observe results.

** Sure enough, the tablet instantly started fizzing, verifying that it
WOULD fizz if there were alcohol in the gas. **

There are a few questions yet to answer

1. Since isopropyl alchohol is 95% pure, that means that it is 5%
water. Is the tablet fizzing only because of the 5% water?

2. However, even if this were the case, would it not also be true that
the presence of ethanol in the car gas would ALSO introduce water, and
thus fizz the alka-seltzer regardless? In other words, is it
irrelevant that the alka-seltzer might only be fizzing because of the
water, if water always accompanies alcohol in gas?

Either way, the fizzing would indicate the presence of water OR
alcohol, or just alcohol that is "saturated" with water -- both of
which would indicate a "No Buy".

Right?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

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  #2  
Old July 20th 06, 05:19 AM posted to rec.aviation.piloting
Jose[_1_]
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Posts: 1,632
Default Testing the Testing of Mogas

Part III: 1. Add some alchohol to aforementioned cup of gas, approximating a 10%
mixture....


Part IV. 1: Add a tablet to pure gas, and then add alcohol (stirring)
until the tablet starts fizzing. Calculate the percentage of alcohol
needed, repeat Part III with that quantity.

Part V: Repeat Part IV, substituting water for alcohol.

Part VI: Add alka-seltzer to the beer that's in the cooler.

Ok, I just added that to see if you were paying attention.

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.
  #3  
Old July 20th 06, 05:32 AM posted to rec.aviation.piloting
Crash Lander[_1_]
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Posts: 233
Default Testing the Testing of Mogas

Not at all a scientific type person, so this may be a dumb question, but is
there any way to evaporate the water out of the isopropyl alcohol without
burning off the alcohol, or is the evaporation point of the alcohol lower
than that of the water? If so, could you evaporate the alcohol out of the
water, and collect the pure alcohol that way?
Crash Lander

--
I'm not always right,
But I'm never wrong!
"Jay Honeck" wrote in message
oups.com...
Plop-plop, fizz-fizz... :-)

In a previous thread I outlined the new (vastly more convenient)
"alka-seltzer method" of testing your mogas for both ethanol and water
-- but (for those who missed it) here it is again:

1. Tap a few ounces of suspect gas into a cup
2. Drop 1/4 of an alka-seltzer into the gas
3. If no fizz, no alcohol or water is present, and the gas is "good"

The question was/is: Is it chemically valid to expect alka-seltzer to
fizz in the presence of alcohol?

Mary (with her minor in chemistry) and I (with my English degree that
allows me to, er, write about this) devised the following empirical
test:

Part I:

1. Purchase a bottle of 95% pure isopropyl (rubbing) alcohol. While
it's not ethanol, Mary determined that the chemical make-up is similar
enough for this test.

2. Pour a few ounces into a cup.

3. Add 1/4 tablet alka-seltzer to the alchohol.

4. Observe results.

** Sure enough, the tablet instantly starting fizzing.**

Part II:

1. Go to gas station we always buy our gas from.

2. Pump a few ounces into a cup.

3. Add 1/4 tablet alka-seltzer to the cup.

4. Observe results.

** Sure enough, the tablet just sat there -- no fizz.**

Part III:

1. Add some alchohol to aforementioned cup of gas, approximating a 10%
mixture.

2. Observe results.

** Sure enough, the tablet instantly started fizzing, verifying that it
WOULD fizz if there were alcohol in the gas. **

There are a few questions yet to answer

1. Since isopropyl alchohol is 95% pure, that means that it is 5%
water. Is the tablet fizzing only because of the 5% water?

2. However, even if this were the case, would it not also be true that
the presence of ethanol in the car gas would ALSO introduce water, and
thus fizz the alka-seltzer regardless? In other words, is it
irrelevant that the alka-seltzer might only be fizzing because of the
water, if water always accompanies alcohol in gas?

Either way, the fizzing would indicate the presence of water OR
alcohol, or just alcohol that is "saturated" with water -- both of
which would indicate a "No Buy".

Right?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"



  #4  
Old July 20th 06, 05:33 AM posted to rec.aviation.piloting
Jay Honeck
external usenet poster
 
Posts: 3,573
Default Testing the Testing of Mogas

Not at all a scientific type person, so this may be a dumb question, but is
there any way to evaporate the water out of the isopropyl alcohol without
burning off the alcohol, or is the evaporation point of the alcohol lower
than that of the water? If so, could you evaporate the alcohol out of the
water, and collect the pure alcohol that way?


Dunno, but someone "up-stream" stated that it was very difficult to get
"100% pure" alcohol because it absorbs water so readily.

In fact, they said that just leaving the cap off the bottle would cause
it to become impure, because it would absorb water almost instantly.

Therefore, I presume the answer to your question is "no" -- but it's
certainly open to debate.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

  #5  
Old July 20th 06, 05:34 AM posted to rec.aviation.piloting
Jay Honeck
external usenet poster
 
Posts: 3,573
Default Testing the Testing of Mogas

Part VI: Add alka-seltzer to the beer that's in the cooler.

Ok, I just added that to see if you were paying attention.


Whew! I thought you were committing alcohol abuse there, for a
minute...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

  #6  
Old July 20th 06, 06:31 AM posted to rec.aviation.piloting
Gene Seibel
external usenet poster
 
Posts: 223
Default Testing the Testing of Mogas

Have you tried the test in gas with ethanol?
--
Gene Seibel
Gene & Sue's Aeroplanes - http://pad39a.com/gene/planes.html
Because we fly, we envy no one.

Jay Honeck wrote:
Plop-plop, fizz-fizz... :-)

In a previous thread I outlined the new (vastly more convenient)
"alka-seltzer method" of testing your mogas for both ethanol and water
-- but (for those who missed it) here it is again:

1. Tap a few ounces of suspect gas into a cup
2. Drop 1/4 of an alka-seltzer into the gas
3. If no fizz, no alcohol or water is present, and the gas is "good"

The question was/is: Is it chemically valid to expect alka-seltzer to
fizz in the presence of alcohol?

Mary (with her minor in chemistry) and I (with my English degree that
allows me to, er, write about this) devised the following empirical
test:

Part I:

1. Purchase a bottle of 95% pure isopropyl (rubbing) alcohol. While
it's not ethanol, Mary determined that the chemical make-up is similar
enough for this test.

2. Pour a few ounces into a cup.

3. Add 1/4 tablet alka-seltzer to the alchohol.

4. Observe results.

** Sure enough, the tablet instantly starting fizzing.**

Part II:

1. Go to gas station we always buy our gas from.

2. Pump a few ounces into a cup.

3. Add 1/4 tablet alka-seltzer to the cup.

4. Observe results.

** Sure enough, the tablet just sat there -- no fizz.**

Part III:

1. Add some alchohol to aforementioned cup of gas, approximating a 10%
mixture.

2. Observe results.

** Sure enough, the tablet instantly started fizzing, verifying that it
WOULD fizz if there were alcohol in the gas. **

There are a few questions yet to answer

1. Since isopropyl alchohol is 95% pure, that means that it is 5%
water. Is the tablet fizzing only because of the 5% water?

2. However, even if this were the case, would it not also be true that
the presence of ethanol in the car gas would ALSO introduce water, and
thus fizz the alka-seltzer regardless? In other words, is it
irrelevant that the alka-seltzer might only be fizzing because of the
water, if water always accompanies alcohol in gas?

Either way, the fizzing would indicate the presence of water OR
alcohol, or just alcohol that is "saturated" with water -- both of
which would indicate a "No Buy".

Right?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"


  #7  
Old July 20th 06, 06:41 AM posted to rec.aviation.piloting
Jay Honeck
external usenet poster
 
Posts: 3,573
Default Testing the Testing of Mogas

Have you tried the test in gas with ethanol?

Nope.

That's next!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

  #8  
Old July 20th 06, 06:45 AM posted to rec.aviation.piloting
Morgans[_3_]
external usenet poster
 
Posts: 407
Default Testing the Testing of Mogas


"Crash Lander" wrote

Not at all a scientific type person, so this may be a dumb question, but

is
there any way to evaporate the water out of the isopropyl alcohol without
burning off the alcohol, or is the evaporation point of the alcohol lower
than that of the water? If so, could you evaporate the alcohol out of the
water, and collect the pure alcohol that way?


Having been _around_ a "hobby still", I feel somewhat qualified to answer
this.

Alcohol boils at around 187 F.. Don't everyone give me grief. I know it
isn't exact, but it has been a while, and it is not important to this
discussion. Water boils at 212 F.. The alcohol will be gone first, if
heated, or allowed to evaporate.

What you need to do, is use a still, to heat the water and alcohol, and hold
the temperature at the coils at 187 F, until nothing is condensed from the
still's cooling coils. The percentage of alcohol (not the proof) will be at
best 98 percent. It takes some very good tricks to get the rest of the
water out, that will be out of reach for a hobby type of operation.

The only answer to get pure alcohol is from chemical supply houses. That
said, I doubt very much that the alcohol produced to blend with gas is above
98 percent pure. Anyone know, for sure? If it is not 100 percent, then
there we have it; the water in the fuel we need for the test. Back to
Jose's extra test steps, to find out how much water it takes to test
positive.
--
Jim in NC

  #9  
Old July 20th 06, 07:29 AM posted to rec.aviation.piloting
Peter Duniho
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Posts: 774
Default Testing the Testing of Mogas

"Jay Honeck" wrote in message
oups.com...
[...]
There are a few questions yet to answer

1. Since isopropyl alchohol is 95% pure, that means that it is 5%
water. Is the tablet fizzing only because of the 5% water?


You can buy "anhydrous isopropyl alcohol". That is, greater than 99% pure.
It may well be technically impossible to get 100% pure alcohol, due to the
presence of water vapor, but obviously the amount of water available in the
air isn't enough to get the tablet to fizz, since it would carry a similar
amount into the regular gasoline with it when you dropped it into there, and
it didn't fizz at all in that.

So, IMHO question #1 is easily answered.

I'm not entirely sure I'm buying the "isopropyl alcohol and ethanol are
chemically similar enough" argument, but I definitely didn't minor in
chemistry, and that was a long time ago. I'm skeptical simply out of
nature, not because I have any real reason to disbelieve Mary's assumption.
Note, however, that they are chemically different enough that one can kill
you right away in small amounts, while the other may take years and years
except in very large doses.

2. However, even if this were the case, would it not also be true that
the presence of ethanol in the car gas would ALSO introduce water, and
thus fizz the alka-seltzer regardless? In other words, is it
irrelevant that the alka-seltzer might only be fizzing because of the
water, if water always accompanies alcohol in gas?


See above. IMHO, while alcohol may bring with it some small quantity of
ambient water vapor absorbed by it, I would be surprised if it were enough
to affect the results of your test. Furthermore, I agree that if a freshly
opened bottle of anhydrous isopropyl alcohol absorbs enough water to be the
sole reason for the tablet fizzing, then surely the alcohol present in gas
would have absorbed enough water to cause the same to happen.

Either way, the fizzing would indicate the presence of water OR
alcohol, or just alcohol that is "saturated" with water -- both of
which would indicate a "No Buy".

Right?


Sure. Though, I'd say that if you need an Alka-Seltzer to tell you that
there is just water in the gas, you're not really trying. Seems to me it's
the alcohol you really care about.

Pete


  #10  
Old July 20th 06, 09:21 AM posted to rec.aviation.piloting
Skywise
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Posts: 140
Default Testing the Testing of Mogas

"Crash Lander" wrote in
:

Not at all a scientific type person, so this may be a dumb question, but
is there any way to evaporate the water out of the isopropyl alcohol
without burning off the alcohol, or is the evaporation point of the
alcohol lower than that of the water? If so, could you evaporate the
alcohol out of the water, and collect the pure alcohol that way?
Crash Lander


Having just read up on isopropyl alcohol the other day for other
reasons, I can help answer this....

[warning! I may have gone overboard on the info]

From http://en.wikipedia.org/wiki/Isopropyl_alcohol

Isopropyl alcohol (also isopropanol)....

Isopropanol is a major ingredient in "dry-gas" fuel additive.
In significant quantities, water is a problem in fuel tanks as
it separates from the gasoline. If the engine tried to combust
the water instead of gasoline serious engine problems could
result. The isopropanol does not remove the water from the
gasoline. Rather, the isopropanol solubilizes the water in
the gasoline. Once soluble, the water does not pose the same
risk as insoluble water.

and...

Isopropyl alcohol forms an azeotrope* with water at 87.4% alcohol.
It is impossible to dehydrate isopropanol further using standard
distillation methods. For this reason, more expensive means, such
as using a drying agent, are necessary for production of 100%
isopropyl alcohol.

*
From http://en.wikipedia.org/wiki/Azeotrope

An azeotrope is a mixture of two or more compounds (molecules)
which at a specific composition (ratio of compounds) maintains
vapor and liquid phases which are in equilibrium and identical
in composition. Due to the uniformity of liquid and vapor,
chemical composition of the azeotrope cannot be changed by
simple boiling (distillation).


So that explains why isopropanol is difficult to purify. Also,
as others have questioned, I'm not sure isopropanol is a good
substitute for ethanol for this test.

From http://en.wikipedia.org/wiki/Ethanol

The product of either ethylene hydration or brewing is an
ethanol-water mixture. For most industrial and fuel uses,
the ethanol must be purified. Fractional distillation can
concentrate ethanol to 96% volume; the mixture of 96% ethanol
and 4% water is an azeotrope with a boiling point of 78.2 C,
and cannot be further purified by distillation. Therefore,
95% ethanol in water is a fairly common solvent.

So both alcohols will contain some water. Although you may
be able to obtain pure isopropanol, obtaining pure ethanol
is practically impossible.

From the article on ethanol,

In most jurisdictions, the sale of ethanol, as a pure substance
or in the form of alcoholic beverages, is heavily taxed. In order
to relieve non-beverage industries of this tax burden, governments
specify formulations for denatured alcohol, which consists of
ethanol blended with various additives to render it unfit for human
consumption. These additives, called denaturants, are generally
either toxic (such as methanol) or have unpleasant tastes or odors
(such as denatonium benzoate).

Some info on Alka-Seltzer...
From http://en.wikipedia.org/wiki/Alka_Seltzer

Alka-Seltzer is a combination of aspirin (acetylsalicylic acid),
baking soda (sodium bicarbonate) and citric acid...

...which are dissolved...in a glass of water. As the tablets
dissolve, the acid and bicarbonate react vigorously producing
carbon dioxide gas

From http://en.wikipedia.org/wiki/Sodium_Bicarbonate

Sodium bicarbonate, when exposed to an acid, releases carbon
dioxide and water


Based on all the above, I would surmise that Alka-Seltzer not
fizzing in gas is simply due to it not dissolving, thus not allowing
the bicarb and citric acid to mix and thus react. The presence of
ethanol or water in the fuel is what permits the dissolving of the
tablets and thus the fizzing.

In the long run, I'd say the only way to be sure is to test several
samples of fuel with known quantities of ethanol and/or water to
determine at which levels the Alka-Seltzer would react. I'd also
try several samples of known 'good' fuel as a control. You should
also verify the samples with other known good testing methods.

Oh, I'd also try crushing the tablets and trying known 'good' fuel
to see if that allows the reaction to proceed.

IHTH

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?
 




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