When you look at filters and biofuels there is one area that consistently causes problems—the behavior of ethanol and water. With E10 becoming almost ubiquitous and efforts to push E15 or E20, not to mention E85, it’s a good time to review how to minimize the impact of water.
Ethanol is hygroscopic in that it attracts water and once the amount of water reaches a certain threshold—that is impacted by the percentage of ethanol mixed in the gasoline and temperature—then phase separation occurs and that alcohol-water mixture separates out and settles to the bottom of the storage tank. The result is two layers in the tank – a top layer of gasoline with reduced ethanol content (and typically reduced octane) and a bottom layer of ethanol/water that will not run in an engine, yet will often rise above the tank intake and head straight to the dispenser. Hopefully, there is an appropriate filter in place to keep this mixture from entering a customer’s tank.
A conventional gasoline/water filter will work on pure water contamination. A phase separation filter will work on the alcohol/water mixture and dual filters can work on both.
“The biggest problem I see in the industry is mainly in the ethanol realm and that primarily involves phase separation,” said Michael Gruca, product engineer for Champion Laboratories. “The retailer doesn't think there's any water in the tank by the way they've tested in the past. With neat gasoline, the water would not bond with it until you got enough in the bottom of the tank to get over the intake. And with the tanks pitched off to one side the water would settle on one side and you suction it off.”
The reason for that is the relatively small amount of water required to cause serious problems. Gruca noted that the striker plates on the bottom are raised half an inch and that there could be enough water just below that to knock a tank into phase separation at a level above the intake. There are some precautions that are important to minimize headaches with bringing a tank online with ethanol fuel.
“First, the tank has to be dry—no water,” said filter manufacturer Cim-Tek’s research and development manager Kevin Hughes. “The tanks should be brand new if possible, though the expense usually does not make this possible. If it’s an existing tank, have the tank cleaned and the lines. Older tanks usually have a build-up of gums and varnish and all sorts of stuff and ethanol will scour that off. It will not do that all at once—it will find a weak spot and begin working on that and you start to get particles in the flow and that will begin plugging up your filters. The lines are harder to clean, but if you don’t you will still be changing your filters in the first 24 hours because the ethanol will scour them as well.”
This recommendation is similarly echoed by Gruca. “Before that first load, take it down as far as you can to confirm that you don’t have any water,” he said. “The ethanol should not be as diluted that way and you can manage a little water. In E10 you can have .5 percent in suspension at 60 degrees and you won’t have any problem until you exceed that.”
Switching between ethanol fuel and neat conventional gasoline can amplify the problem. “Then you have the scenario where people start out with the alcohol then switch back to neat gas and if you take 10,000 gallons of E10 and take it down half way then fill it with neat gas, you now have E5,” said Gruca. “And if you do it again you have E2.5, and the lower the alcohol content, the easier it is to take it into phase separation and knock out whatever alcohol is there. And it doesn’t take much of that to slam the filter shut.”
There are additional issues with both very old and brand new tanks. “If you have tanks that are really old, you want to make sure they are compatible with an ethanol blended fuel,” Hughes said. “With steel tanks, you have to make sure they have a coating to protect from rust, and with older fiberglass tanks you want to check with the manufacturer to make sure everything is compatible. It’s not as much of a problem with E10 compared to E85, but with older tanks the ethanol can degrade the resin, which will end up in the fuel.”
And even with brand new tanks, Hughes noted that it’s a common instillation practice to use water as ballast. If that water is not fully removed, by hand through a confined entry if possible, the same water issues can come into play as those involving an existing tank.