RC Fuels Nitromethane, Castor Oil, Synthetic, heli fuel, 4 stroke, etc...Fuel Q&A is here!

How to remove water from fuel

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Old 10-19-2005, 03:06 PM
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donkey doctor
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Default How to remove water from fuel

Hello; We all know that the methanol in our fuel attracts water from the atmosphere. There is another thread here which may be solved by removing the water from the fuel. I remove water from my fuel by freezing my fuel bottle then pour ing the frozen fuel off into a clean dry bottle. It leaves the water frozen to the bottom of the jug.

a friend (Bill bond) decided to find out just how much water our fuel could contain before the engine wouldn't run. He did all his experiments in a controlled environment, and added water in percentages. First he added 5%, no change, then another 5% for a total of 10%, no change. Then he added another 10% water to the blend, the top end was reduced 200 rpms. He tried the same experiment on a four stroke engine (an Eny 60) and got the same results 200 rpms at a 20% water added. The fuel was milky with the water combining with the oil. Now I wouldn't recommend anybody water their fuel down to make it last , and this test doesn't deal with long-term effects.
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Old 10-19-2005, 03:41 PM
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Default RE: How to remove water from fuel

Yep its true. Don't forget that many piston engine planes, such as the Corsair has water injection for short bursts of extra power. Shake it up and fly it, most fuel accumulates less than .1 percent water.

Exposure to direct sunlight will cause problems with the nitro however.
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Old 10-19-2005, 04:28 PM
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Default RE: How to remove water from fuel

From my experience, sunlight does as much damage as anything.

Fuel that's sat in the direct sun for a few weeks will have very unstable running characteristics and will get so bad that the glow plug will not stay lit.
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Old 10-19-2005, 05:50 PM
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Default RE: How to remove water from fuel

Water,alcohol injection in the radials acted like an antidetonant allowing them to run a leaner fuel mix for more power.
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Old 10-19-2005, 06:43 PM
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Default RE: How to remove water from fuel

I don't know where I read it but there was an article about water in glow fuel and they also came up with the conclusion that water had no effect on the operation of a glow engine.
Obviously, you can go too far and have too much water but normally, if we get any at all, it is a comparatively tiny amount of water. I agree, sunlight does have an effect.

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Old 10-19-2005, 06:55 PM
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Default RE: How to remove water from fuel

My wife would appreciate all water!!!! Think of the savings?
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Old 10-19-2005, 07:00 PM
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Default RE: How to remove water from fuel

Long time ago when I did tests with added water, running got worse at 5% if I remember correctly. Here is the best documented report of subject I have found by: Brian Hampton.

http://www.holdfastmac.com.au/Waterfuel.html

Unfortunately my methanol with some water was still homogenous fluid at -20C

Industrial grade methanol HC3OH usually contains some water, formic acid and formaldehyde.
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Old 10-19-2005, 07:54 PM
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Default RE: How to remove water from fuel

I haven't actually tried freezing fuel myself but water and methanol do not normally separate by freezing. They are infinitely miscible in simple mixture. While I suppose it is possible to change the mutual solubility by adding a third ingredient (oil) I rather suspect that you might find that a fair proportion of what you froze out of the mixture was the oil, not the water. I would check to make sure but this is obviously not the best situation. Most frozen oil is a fairly waxy solid instead of hard crystals.

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Old 10-19-2005, 07:59 PM
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Default RE: How to remove water from fuel

I think this should be moved to the fuels thread?
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Old 10-20-2005, 06:00 AM
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Default RE: How to remove water from fuel

If allowed to sit for a while the water will settle to the bottom because of it's higher specific gravity. Went to buy a 45 gallon drum of alcohol from a speed shop. The bottom had water in it so I didn't buy it.
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Old 10-20-2005, 06:19 AM
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Ross Kean
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Default RE: How to remove water from fuel

Water WILL NOT settle out of a mixture of methanol and water - ever. They are completely miscible under ordinary conditions. It would be the same as having your ethanol settle out from a bottle of vodka. You may be able to separate cryogenically (at very low temps), by distillation, chromatography or molecular sieves but not by gravity in a simple mixture of alcohol and water.
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Old 10-20-2005, 06:40 AM
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Default RE: How to remove water from fuel

What do you propose that this stuff was that I was siphoning off the bottom?
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Old 10-20-2005, 10:23 AM
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Default RE: How to remove water from fuel

In fridgid Minnesota we know that a little bit of alcohol will disolve a solid chunk of ice in the gas line of a car at 30 below zero. We use to regularly use a bit of alcohol in every tankful of gas during the winter just to prevent gas line freeze up. Unlike alcohol, water does not disolve in gasoline but rather settles to the bottom of the tank where it then freezes.

We also use at mixture of methanol and water for windshield washer.

I have never seen water freeze out of an alcohol/water solution.

And like Ross says, it won't!
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Old 10-20-2005, 10:43 AM
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Ross Kean
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Default RE: How to remove water from fuel


ORIGINAL: Flypaper 2

What do you propose that this stuff was that I was siphoning off the bottom?

As I mentioned in my earlier response, I suspect that the stuff that froze out was mostly oil - possibly with some methanol dissolved in it. I also said that in simple mixtures, water does not freeze out of methanol but who knows for a mixture that contains methanol, castor oil, synthetic oil, dyes, stabilizers, nitromethane and water. When you look at relative solubilities, I think it is far more likely that the oil has come out of solution rather than water. I haven't tried it myself - just speaking from a little knowledge of the physical properties of solutions and mixtures.

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Old 10-20-2005, 01:02 PM
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Default RE: How to remove water from fuel

Hello Ross. You said that it won't happen, but you haven't tried it. Try it, see what you get. it's one thing to theorise but to claim that your theory is fact without testing, isn't very scientific. I have a chest freezer, set at -14F. If I put a gallon of fuel in it, the next morning I am left with 2 or 3 ounces of ice in the bottom of the jug. Ppour off the fuel, melt the ice and pour off what is left. It has the consistancy of water, the feel of water (as opposed to oil), and it won't burn or evaporate like alcohol does. I didn't taste it, but I would bet it's water.

We use methanol in our air dryers in our logging trucks our here to remove water from air systems, so I hear what you're saying, but it works regardless what theory says.
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Old 10-20-2005, 02:02 PM
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Default RE: How to remove water from fuel

This methanol in the drum had nothing else in it. It was fuel for dragsters.
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Old 10-20-2005, 03:27 PM
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Ross Kean
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Default RE: How to remove water from fuel

First of all, I said that the water would not freeze out (at least not at any reasonable temperature) of a simple solution of methanol and water and that it might be difficult to predict what might happen with a complex mixture. From my experience with other systems, I said that the oil would be more likely to freeze out - based upon physical and chemical properties of very polar (water, nitromethane and methanol) and somewhat less polar (oils of various sorts) substances.

Is there any particular reason why you had 2-3 ounces of WATER in a gallon of fuel?? This is a LOT, even for low-grade chemical products. Typical maximum spec for moderate grade methanol is only 0.2%

I'm not sure why making a hypothesis is contrary to the scientific method. The first step is making a hypothesis and then developing a procedure to test it. I never claimed that it was impossible to have water separate from a complex system but that I thought that there was a more likely explaination for the material that ended out at the bottom of the jug.

I do not intend to test my thoughts so (as far as I am concerned) it remains a theory; not a proven fact. Not unscientific but not proven scientifically. By the same token, since you have not chemically analyzed the frozen/thawed substance, it is still conjecture - just different from mine.

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Old 10-20-2005, 08:58 PM
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Default RE: How to remove water from fuel

Is it possible that you froze the nitro out of the fuel? It is clear and does not have a real strong odor and can be quite difficult to set on fire with a match, especially if it is cold.
Gasoline will come out of solution with alcohol at low temperatures, especially if there is water in the alcohol, so maybe nitro will too.
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Old 10-20-2005, 09:01 PM
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Default RE: How to remove water from fuel

Ross is right, water will not seperate from alcohol, even at freezing temperatures. In fact we have all done this experment when we put windshield washer fluid in our cars. It is a mixture of methanol, water, and soap. It will not freeze, unless maybe you drive to the Arctic. If you found a solid in a freezing cold jug of fuel, is was likely a mixture of oil and water. Castor oil will disolve a bit of water and the two will make a hard gel at the bottom of the jug. It turns into a whiteish color as well.
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Old 10-20-2005, 09:41 PM
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Default RE: How to remove water from fuel

Here is an interesting site. http://www.ashchem.com/adc/chemicals...=3&is_header=N
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Old 10-21-2005, 06:08 AM
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Default RE: How to remove water from fuel

THe freezing point for nitromethane is around -29 degrees C so at -14, it won't freeze by itself although it could come out as a frozen mixture of some sort containing a fairly high percentage of nitro. Methanol and water are miscible at essentially any temperature and ratio and water won't freeze out under normal circumstances. Strange things, however, can happen with a somewhat more complex mixture such as fuel. I would concede the possibility (not liklihood) that the oil in the system could modify the ionic strength properties of the mixture sufficiently to reduce the solubility of water at very low temperatures. I guarantee that all of the water won't come out and I can also guarantee that the frozen stuff isn't pure anything.

The discussion about water in fuel has been going on for a very long time. There are those who will tell you that any water in fuel is the "kiss of death" with respect to reliable operation of glow engines. There is enough fairly recent information to suggest that a fairly large amount of water may not be such a big deal - at least to the point where the fuel becomes milky due to oil separating and coming out of solution. The oil is the least soluble (in methanol) component in the system and when ionic strength is increased by the addition of a very polar solvent such as water, the oil's solubility is decreased to the point where it separates.

I suspect that the problems associated with fuel that has been left open have more to do with evaporation of the volatile methanol which effectively increases the solution concentration of the oil and nitromethane; possibly to the point where it does not work well. (nitro and oil are far less volatile than the alcohol) Decomposition of the nitromethane could also be an issue with extended direct exposure to sunlight.

Sometime when I have nothing better to do, I might do a controlled freezing experiment with pure, clean fuel and some with a little (5%) water added and compare the results. Note: Just because there may be more precipitate with the water-modified fuel doesn't mean that the stuff is water. As above, the more water that is in a system, the less oil that will remain in stable solution. I would compare the amounts of frozen residue and analyze the chemical composition. I don't think a little water makes enough difference to matter but curiosity may eventually get to me! If there is ANY possibility that the gunk that freezes out is oil, oil/water or oil/nitro I would avoid that practice. Your engine may run on substantially reduced oil content but it certainly won't do it any good!

Ross

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Old 10-21-2005, 09:46 AM
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Default RE: How to remove water from fuel

ORIGINAL: Ross Kean
I might do a controlled freezing experiment with pure, clean fuel and some with a little (5%) water added and compare the results.
Ross,
The article I wrote in that link in post #7 (thanks esamart ) was with zero nitro fuel and around 2% water was enough to drive the oil out of suspension at room temps. I ended it up by saying it'd be interesting to compare the affects using a fuel with nitro because I don't use the liquid gold. Maybe you could try experimenting with various percentages of nitro.

The way I did it was to fill a syringe with 100cc of fuel then add .25cc of water for the first freeze test then add another .25cc for the second, another .25cc etc. That way I only wasted 100cc of fuel (I'm an Aussie, we're cheapskates ).
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