Phase Separation of Ethanol Fuel – Problems of Alcohol Fuel

The phase separation of ethanol fuel or ethanol and gasoline fuel blends is now one of the major alcohol fuel problems that ethanol fuel users now face.

The presence of ethanol in gasoline has raised concerns especially when some fuel suppliers started mixing ethanol in gasoline without informing consumers. So if you use gasoline for your vehicle, boat, motorcycle, generator, lawnmower, heater, or any other engine-powered equipment, make sure you know whether there is ethanol in your fuel.

This is because the presence of ethanol in gasoline can cause certain reactions that do not normally occur with gasoline alone. By being informed of your fuel’s ethanol content, you can prevent these negative reactions from occurring. For example, you can keep your ethanol fuel from coming into contact with water or being exposed to humidity. This is due to the phase separation of ethanol fuel.

Definition of Phase Separation

Ethanol phase separation refers to the chemical reaction that occurs when a " gasoline and ethanol blend mixes with water ", either as a liquid or in its humidity form. What happens is that ethanol absorbs either some or all of the water. By the time the mixture reaches a saturation point, the ethanol and water will phase separate or, in other words, break free from the solution.

You will know that phase separation has occurred when the gasoline, water, and ethanol form different layers in the container. Sometimes, only the gasoline and ethanol are noticeable, with the ethanol forming a milky layer underneath the gasoline. In other cases, you can also see a layer of water at the bottom.

When this happens, the gasoline and ethanol will no longer be blended together and will be rendered useless because of the presence of water in the tank. If the engine draws only water, your vehicle will not start. But if the engine is running when phase separation occurs and it draws water unexpectedly from the tank, a thermal shock or hydro-lock can occur.

However, if the engine picks up the ethanol and water mixture or just the ethanol, it can suffer major engine problems. If the engine picks up the gasoline alone, you will notice that your vehicle will no longer operate at the higher octane rating of ethanol.

Preventing Phase Separation of Ethanol from Gasoline

To prevent phase separation in ethanol blended gasoline from occurring, it is important to keep the mixture away from water and to make sure that the vents that release humidity from the tank are working well. If minimal water contact is unavoidable, make sure to keep the mixture at the right temperature.

If you are using E10, a blend of ethanol fuel that holds 10% of ethanol and 90% of gasoline, the resulting mixture can hold around .05% of water at 60 degrees Fahrenheit without causing phase separation. This is equivalent to just 3.8 teaspoons of water in a gallon. However, as temperature changes, so will the ethanol fuel’s capacity to hold water. At 20 degrees Fahrenheit, the ethanol fuel blend can only hold around 2.8 teaspoons of water.

The Dangers of Phase Separation for Boats and Other Engines

Some engines are not as equipped as automobile engines in resisting the negative effects of phase separation of ethanol fuel. For example, some boats, especially older ones that were built before 1993, have fiberglass fuel tanks.

When phase separation occurs, the 100% pure ethanol can react with some of the materials used to make the tank. This can weaken the tank and can cause engine failure. In the worst case scenario, ethanol can cause some parts of the fiberglass tank to dissolve and the material to be carried through the fuel system, thus affecting the carburetor, fuel injectors, and combustion chambers. Once the material affects the valves and pistons, they will be almost impossible to remove without affecting the components of the engine.

Other engines can also have more problems with ethanol blended fuels than some, so before using ethanol fuels, make sure your engine is designed to handle it and that there is no water in the tank to prevent phase separation.