The amount of water that ethanol can absorb, particularly when mixed in fuel blends, is limited and significantly affected by temperature. The provided information details the water tolerance of a specific blend: a 10% ethanol mix.
Understanding Water Tolerance in Ethanol Fuel Blends
While pure ethanol is highly hygroscopic (meaning it readily attracts and absorbs water), its ability to hold water when blended with gasoline is limited. This limit is known as the blend's water tolerance. If the amount of water in the fuel blend exceeds this tolerance, a phenomenon called phase separation occurs. This is where the water, along with some of the ethanol, separates from the gasoline, forming a distinct layer at the bottom of the fuel tank. Phase-separated fuel can cause significant engine problems.
Impact of Temperature on Water Tolerance
Temperature plays a crucial role in how much water an ethanol fuel blend can tolerate. Colder temperatures reduce the blend's ability to keep water dissolved. As the temperature drops, the risk of phase separation increases even with small amounts of water present.
Water Tolerance of a 10% Ethanol Blend (E10)
According to the reference provided, the water tolerance for a 10% ethanol blend (commonly known as E10) varies with temperature:
| Temperature | Approximate Water Tolerance (for 10% Ethanol Blend) |
|---|---|
| 60°F | approximately 0.5% water |
| 10°F | approximately 0.3% water |
This means that at colder temperatures, the fuel blend can hold less water before phase separation occurs. The lower the temperature, the lower the water tolerance. Exceeding these small percentages of water can lead to serious fuel system issues.
