Phase Separation and Water in Ethanol

June 18, 2008

Phase Separation.

We recently witnessed a case of phase separation where a fellow service company advised our customer to dispose of over 7,000 gallons of perfectly good gasoline. The service company unfortunately did not know how to detect where the phase separation had occurred in this fuel  and assumed the entire tank had been contaminated.  We took samples from this tank and verified that there was less than 8% phase separtation of 7500 gallons  E10 fuel effected by the water.

Phase separation occurs when Ethanol blended fuels comes in contact with water. The water is absorbed into the ethanol and separates or drops out of the fuel then falling to the lower portion of the holding tank. Depending on where the water came from it will look different in various situations. The first sign of phase separation is a distinct haze in the fuel. If the water was dirty or rusty you will also see this which makes it easier to detect.

Using an ethanol friendly water paste is a great way to tell the water levels you are dealing with. Sar-Gel and Gasoila both have great products. We encourage customers to stick their tanks with water paste daily at the fill and if possible periodically at the monitor area as well. Most ATG tank monitor systems are not designed to detect phase separation.  In addition, Because the fill is usually away from the STP it is best to stick the tank in multiple locations when possible. Tanks are usually tapered one way and have a low end. Often the low end is not the fill, where most tank owners check for water.

Once you have confirmed you have phase separation, depending on the amount, you may have to rebuild your octane rating. In most cases we have found that the octane rating has not been altered but it is possible to lose your octane rating when dealing with larger amounts of phase separation. It is best to call your fuel supplier and ask them what type of blending they do. Some ethanol is blended ontop of its Octane, for example 93 octane. Fuel that is blended in this manner will usually maintain a higher octane rating because Ethanol was not used to build its initial octane levels. It is always best to discuss your situation with your supplier however. In most cases, it is more economical to build up your octane rating with the good fuel you do have rather than dispose of the entire tank. You can rebuild octane levels by blending higher octane fuel into your current quantity and have it tested to confirm octane levels and quality.  

For more information please contact us.

Written by Chris Runge
Clean Fuel Technologies