‘Washing’ ethanol out of mogas – Part II

Back in November 2010 I wrote a blog about separating ethanol from E10 by a method that is commonly known as “washing.”

Looks like pilots don’t get it. There has been an ongoing conversation on backcountrypilot.org about separating ethanol from auto fuel by “washing” it out with water — scroll down to the entry by “EZFlap” and read on.

It got really interesting when the owner of this device advertised it on that thread, Portable Fuel Systems. The message was removed, I assume for being crassly commercial. What is interesting is that Portable Fuel Systems implies that the ethanol washing version is suitable for aviation use while only advertising the portable tank version in their aviation section. However in the description of the ethanol separation version, this statement is made, “The PortableFuelSystems Alcohol SeparationSystem is currently in the prototype phase, and has been successfully providing fuel to aircraft since 2009. A-S-S will be released for shipment Oct. 20, to coincide with the Copperstate Fly-In in Casa Grande, Arizona.” The post on backcountrypilot.org stated that the device was indeed shown at Copperstate.

Unfortunately the ad for this device and the statement made on backcountrypilot.org implies that you can use this device to remove ethanol from auto gasoline and use it in any airplane. This couldn’t be further from the truth. You cannot use the resulting product, whatever it is, in a Type Certificated airplane with an auto gas STC. There is no way to guarantee that the resulting product is gasoline that is ASTM D4814 compliant and, in fact, it probably isn’t. To understand why, I urge you to read my original blog noted above. In addition, the resulting water, ethanol, or whatever mixture is considered hazardous waste and must be handled appropriately.

The authors of this blog would again like to urge our fellow aviators to put their efforts into getting mogas on our airports. Communicate with the FAA, EAA, AOPA and other aviation alphabets and the EPA and tell them why we need mogas service on the majority of our airports, and ask them why we don’t have one of the approved aviation fuels widely available. Putting up with ethanol fuel blending and then buying expensive equipment to try to remove it and ending up with an unknown fuel product is not worth the liability or the expense.

Dean Billing

The GAfuels Blog is written by two private pilots concerned about the future availability of fuels for piston-engine aircraft: Dean Billing, Sisters, Ore., an expert on autogas and ethanol, and Kent Misegades, Cary, N.C., an aerospace engineer, aviation sales rep for U-Fuel, and president of EAA1114.


  1. Jscott says

    Yes, Portable Fuel Systems was indeed showing their device at Copperstate and claimed it should be on the market soon, probably via Aircraft Spruce as one of the vendors.  I talked to them briefly.  Their claim is that the process will remove all the Ethanol from the gasoline leaving regular unleaded fuel.  However, as we all know, the companies don’t use regular unleaded gasoline then add ethanol.  They add Ethanol as the anti knock compound to very low octane feed stock to make the finished gasoline product.  Even if the Portable Fuel Systems unit works exactly as advertised, your 87 octane Ethanol contaminated gas would separate out into roughly 83 octane mogas without the Ethanol.  A 92 octane fuel would likely separate down to an 87 octane fuel, so one *might* be able to successfully run it in a low compression engine.  But as stated in the article, there is no guarantee of meeting any ASTM qualities.

    Kent, with a little more investigation, the actual break downs might make for an interesting future article.

    • Dean says

      Aircraft Spruce already represents their plain vanilla portable tank, it is in their catalog and on their web site.  I seriously doubt that they would ever sell the A-S-S system.  That would be a serious liability issue for them.

    • Todd says

      E10 gas octane rating is 87.  Octane rating for EtOH is 108.6 (
      http://en.wikipedia.org/wiki/Ethanol ).  What components of gasoline are removed by washing?  None of them?  What components of ethanol are removed by washing?  All of them?  These are questions with presumptions; I do not know for sure.  In terms of the octane: 870 (ten parts of e10 averaging to 87) -108.6 (the octane rating of the 1/10 that is ethanol) = 761.4 >>>761.4/9 (remaining nine parts of gasoline) = 84.6 octane rating.  

      Help me with this part of the first article:

      “So what is this “fuel”?  How will you describe it on the placard? This is what the director of the Division of Air Resources, New York State Department of Environmental Conservation said in his comments on the E15 waiver:
      “E10 is not simply ethanol added to finished gasoline. Since most gasoline at retail contains ethanol, the industry factors the addition of ethanol into the formulation of the petroleum-based portion of the final blend. The chemical properties of ethanol and its dilution impact allow refiners to produce a petroleum-based blendstock which when combined with a specified amount of ethanol (or other oxygenate) results in a final blend with the desired legal and market properties. The petroleum-based blendstock, in most cases, would not qualify as gasoline or be legal to sell as gasoline. For RFG this blendstock is RBOB. For conventional gasoline it is CBOB, and for California RFG it is CaRBOB.”
      RFG = ReFormulated Gasoline
      RBOB = Reformulated gasoline Blendstock for Oxygenated Blending
      Can’t find acronyms for CBOB or CaRBOB but why would they be based on BOB which refers to oxygenated blending?
      I know that ethanol is not introduced at the refinery and the distribution for EtOH is OTR trucking.  If conventional gas from the refinery is vastly different  from gas that is to be the main component of E10, then the refineries follow two different refining/additive processes?
      AFAIK, CA is not an ethanol-mandatory state but an ethanol subsidizing state.  IOW, if the state pays the gas suppliers more than it costs to introduce the ethanol, why would any supplier not include it?  BTW, made a convenient stop 4 hours away in AZ for a pure gas stop last Wednesday; no pure gas in CA.
      All of this in a state where the Federal District that has allowed a case to go forward for the purposes of removing all lead from avgas through an endangerment finding from the EPA.  Coming and going, I tell you.

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