/ Water Solubility Table
Ethanol is very sensitive to water with
water solubility of 100% at 70˚F.
A 10 v% ethanol blend has a water
tolerance of ~ 0.45% at 60˚F
The table shows tolerance of 3 comon
Once a gasoline ethanol blend reaches water saturation,
results in a lower phase of alcohol and water and an upper phase, of predominantly hydrocarbon
The amount of water that the three common
ethanol blend levels can tolerate Before phase separating (at 60˚F) is
Source: Oak Ridge National
LaboratoryEthanol Project Subcontract
- If a 10% ethanol blend is contaminated with over .5%water,
- The ethanol and water mixture will separate from the gasoline and fall to the bottom
of the gas tank.
- This is an inconvenience, because the fuel system must then be drained and new fuel
- Before using ethanol blended fuel for the first time in an older small engine, it is
recommended that the fuel tank be drained to assure that there is not water accumulation.
- Since many outboard motor carburetor problems result from water in the fuel system,
continuous use of an ethanol blend will prevent water accumulation, breakdowns,and maintenance.
PHASE SEPARATION IN STORAGE TANKS
- Ethanol blends require a water free environment.
- Before converting to ethanol blends stations must
first prepare their storage tanks and dispensers to ensure that they are compatible with ethanol blends and are tight against
- The system must always be maintained free of water.
- This is extremely important since ethanol will bond with
the water and pull it up into the fuel.
- Once there it can remain in this cloudy state until the
temperature of the fuel cools or the water and ethanol saturation becomes so heavy that it drops away from the lighter gasoline
- The water or water and ethanol mixture settles
to the bottom of the container leaving the lighter gasoline on top.
- This is known as phase