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Old Dec 24, 2007, 11:10 AM
arukum17 is offline
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Shelf life of glow fuel


Properly stored, how long should an opened bottle of 5% nitro glow fuel last before it simply will not start an engine?
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Old Dec 24, 2007, 11:36 AM
vhoward1122 is offline
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After about a year, you might start having trouble getting your engine to stay running reliably with it. The alcahol in the fuel absorbs water like crazy, so every time you open the jug, you are introducing moisture. If you haven't used much of the gallon, then you should be able to store it longer. If you have opened the jug enough times to have used half of the gallon, then storage time reduces.
Old Dec 24, 2007, 12:23 PM
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If the container is kept tightly closed, the fuel should last for many years. While it is true that alcohol will absorb water from the atmosphere, how many times have you seen a closed bottle of fuel expand to a larger volume?
Old Dec 24, 2007, 12:29 PM
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My half-gallon container is about 1/4 full and 5 years old...(but always kept tightly closed and never left open for more than a few seconds, during this 5 year period I have opened the bottle maybe 15-20 times, as I use glow very infrequently)

starts my .049 cox. But won't start my new K&B 20 engine (engine sputters for a second but wont vroom)
Last edited by arukum17; Dec 24, 2007 at 01:42 PM.
Old Dec 24, 2007, 01:23 PM
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If you use it that infrequently, then I would buy it by the quart. Try some new fresh fuel. You might be surprised.
Old Dec 26, 2007, 10:26 AM
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Quote:
Originally Posted by 706jim
If the container is kept tightly closed, the fuel should last for many years. While it is true that alcohol will absorb water from the atmosphere, how many times have you seen a closed bottle of fuel expand to a larger volume?
There is an old high school experiment that pours a couple of ounces of water into a gallon on alcohol and the volume does not change. Odd but then the alcohol molecule is very large and there is a lot of space around it. The water molecule is very small, and fits in and around the larger alcohol molecule.

So it takes quite a bit of water to change the volume of alcohol based fuel. Your comment, ergo, is full of beans. You can absorb a tremendous amount of water and not see the volume in the fuel container change very much.

But then a little water in the fuel is not bad, a lot is. But a small percentage, maybe one percent or so, will not effect anything and may give you a little more power. A lot of water is big trouble as it does not burn. The small amount turns into steam and has a great expansion rate, so it boosts the mass of air/fuel going through the engine. More mass, more power. Too much water no power.

I would not go adding water to the fuel but people have experiemented with the water addition. We used water injection in jet engines for years to get more thrust. A thorough Internet search may reveal more on the subject.

Cheers,

Chip
Old Dec 26, 2007, 10:41 AM
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Ultimately my new 2 stroke engine is not starting with this fuel...my cox .049 ran fine on this fuel (although that was 8 months ago) but I heard cox's will run on anything, so not really a benchmark.

Is there anyway of testing wether 5 year old fuel is OK without actually running it in an engine? Smell, combustion ability etc? Sort of the way one tests a glow plug's orange glow without actually running it in an engine.
Old Dec 26, 2007, 11:18 AM
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"Your comment ergo is full of beans".

I guess my point is that the fuel will be fine if the container is kept closed. The absorption of water and evaporation of methanol/ nitromethane fuel components due to an uncapped fuel container WILL cause all sorts of problems.
BTW, I never knew about the high school experiment with the alcohol. And I have a chemistry degree! (Oops!)
Old Dec 26, 2007, 02:53 PM
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Quote:
Originally Posted by Chip01
There is an old high school experiment that pours a couple of ounces of water into a gallon on alcohol and the volume does not change. Odd but then the alcohol molecule is very large and there is a lot of space around it. The water molecule is very small, and fits in and around the larger alcohol molecule.

Hmmm, I'll have to try that experiment, I don't have pure water or alcohol though, so I'll have to make do with what I have...

*Pours bourbon in glass*
*pours in coke*
Odd, The volume increased, I'll have to dispose of this test and try again...
Old Dec 26, 2007, 04:20 PM
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I would think a Cox 049 would be much more fussy for fuel than a K&B 20. Glow fuel stays usable for quite some time but 5 years is a long time to have fuel laying around.

Buy some new fuel. You had another post about starting this brand new engine. Once you learn how to operate the engine & have it running properly on the fresh fuel try some of the old fuel. If it runs sick then or you cannot start it you can be sure the old fuel was the problem.

New engines can be tight & hard to start for the first few runs. Don't be affraid to use the starter! Is the engine a K & B 20 'Sportster'? - John.
Old Dec 26, 2007, 04:34 PM
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Yes its the K&B 20 Sportster...
Old Dec 26, 2007, 05:29 PM
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Glow fuel can store nearly indefinitely in a glass jar with a sealed metal lid. The problem with the plastic jugs is that plastic isn't air tight. If you're just running the small engines, then just buy quarts of fuel if you can. Tower sells quarts of 15% for $8.
Old Dec 26, 2007, 06:45 PM
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Sadly, on this side of the pond, most stores (including online) sell only 1/2 gallon and above...

You would blush if I told you how much fuel (and all other RC things) cost in this part of the world...
Old Dec 26, 2007, 08:22 PM
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Fresh, unopened fuel in plastic bottles will last many years if stored in a cool, dry area with no direct sunlight. I keep mine on a shelf under my workbench in the cellar. My club makes a large purchase (2 pallets via common carrier) in the late fall, when our suppliers volume drops off, makes for better pricing, I paid $12.46 a gallon for 15% sport blend. If I had to pay quart prices (I just took delivery of 3 cases ) I'd go to gasoline for sure
Old Dec 28, 2007, 01:04 AM
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Quote:
Originally Posted by arukum17
Properly stored, how long should an opened bottle of 5% nitro glow fuel last before it simply will not start an engine?

------------


I have used properly stored (no light with a cool/steady temp) that was seven years old without a problem. Mine was unopened. I'm sure that makes a difference, but I'm not sure of how much of a difference.

I've used open bottles of fuel a couple of years later with mixed results.


Ed Cregger


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