Fuel Vent Rules Are Out of Whack with Reality

Posted by at 11:05AM - Comments: (6)

December 12, 2012

Our tests found that silicone was more effective than the carbon filter media required by law.

Well, the first year without subsidizing U.S. refiners and farmers for using corn to make ethanol-blended gasoline has passed, and the world didn’t end. Gas prices haven’t soared, growing corn is still profitable, and most of the members of Congress who reversed their political stands are still in office. I’m pretty certain that when historians and economists look back on the 30-year-old, $20-billion tax break for turning corn into fuel, it will be seen for what it is: political pandering masquerading as “clean” energy policy.

Practical Sailor has covered the effects of ethanol on marine fuel systems in depth over the last several years. Most of our focus has been on helping prevent the problems that ethanol causes in engines and fuel system and effective fuel treatments. I bring up politics here only because it relates to our upcoming story (January issue) on recently enacted federal regulations that require fuel-vent filters on new boats. 

Our stand on environmental regulation is simple. We support protecting the marine environment with sound, practical policies that are founded on good science. However, based on our tests with fuel-vent filters, the U.S. Environmental Protection Agency (EPA) and other backers of the new mandate have overlooked some basic facts.

 The new guidelines, designed to reduce emissions of volatile organic compounds (VOCs) into the atmosphere, will require fuel tanks on new boats with gasoline inboards to have vent filters. This isn’t a bad thing. Cars have had these filters since the 1970s. Not only do vent filters reduce emissions, they can improve engine performance. The filters, cylinder-shaped cartridges filled with a granulated filter media, are installed in-line with the vent hose to control the natural “breathing” that releases VOCs. The filters also prevent water vapor from precipitating inside the tank (causing all kinds of headaches) and help preserve fuel quality.

Rather than carry out commonsense tests in the lab or on the water to determine what filter media is practical and effective in the marine environment, the EPA researchers relied on past experience with automobiles, basic lab tests, and a few limited field tests on boats. Its chief oversight? The EPA did not conduct any field tests during the spring, when—as every ethanol-plagued boater knows all too well—wide daily temperature swings accelerate the exchange of gasses inside and outside the tank. Despite widespread use of other filter media, the agency tested only one type of filter media: carbon.

Based on its research, the EPA specified granulated carbon in the filters, as required in cars. The trouble is that after several diurnal temperature changes during a mid-Atlantic spring, carbon granules become saturated. In our experiments, testers could clearly see the water droplets forming inside the carbon filters; there were no such signs of saturation in our filters using silica gel. It appears that even soaked carbon filters still reduce VOC emissions, but as we found, they don’t work in the spring as well as silica-gel pellets. Silicone, it seems, is a more cost-effective and—dare we say—environmentally friendly solution.

It’s not as if the EPA scientists didn’t know about silicone. Silica gel and alumina are used in various industries to keep fuels, compressed air, and hydraulic lines dry. We can only assume that politics and a rush to enact the new regulations got in the way of more sensible research.

What does this mean for boaters? The good news is that with the carbon-granule vent filters, new boats will have less water creeping into their tanks. The bad news? The new filter regulations reveal, once again, that our energy and environmental policy continues to be shaped by politics—rather than by science.

Comments (6)

Your editor is slipping on word usage.

silicone - a usually rubber like polymer, polysilioxane

silicon - an element, atomic number 14

silica - silicone dioxide

silica gel - a very porous, hard, vitreous form of silicon dioxide

Posted by: W S M | January 17, 2013 8:13 AM    Report this comment

John: Stay tuned for the January issue (due out later this month) for our recommendations. We tested two commercially available filters (with carbon and silica gel as filter media, and using E10, diesel, and gasoline) that can be retrofitted to existing fuel systems. The results of those field and lab tests will be in the January article.

Posted by: ANN K | December 13, 2012 8:20 AM    Report this comment

Forewarned is forearmed is certainly applicable in this case as well. As Andrew N observes the addition of a silica filter in the lines to compensate for the "ahem" omission of the obvious is certainly warranted here. Richard S.-G.

Posted by: Unknown | December 13, 2012 5:01 AM    Report this comment

It seems to me that there are two different things here. Carbon for VOC control and silica for moisture control. So it doesn't seem to be a surprise that they don't do the very well at both. Since the govt is only looking to control VOC and is not worried about moisture than carbon would seem to be the choice. I would add the silica filter to the vent line to take care of the moisture.

Posted by: ANDREW N | December 12, 2012 10:00 PM    Report this comment

Any suggestions for current production silica gel/alumina or carbon granule filter kits to retrofit older boats now forced to use ethanol enhanced gasoline.

Posted by: John Mifflin | December 12, 2012 5:59 PM    Report this comment

We all know the problems with ethanol in virtually all internal combustion engines. Many of us believe, as PS seems to, that ethanol laws are "political pandering" and do little to improve the environment or make us energy independent. The cost of this legislation makes everything cost more due to it's diverting of farmland away from food sources, increased cost in engine maintenance, federal subsidies to farmers and fuel suppliers, etc. Is there anyone out there willing to try to overturn this debacle? I suspect that a significant majority of people who understand the problems created by ethanol would help us repeal these laws.

Posted by: Kent R | December 12, 2012 1:51 PM    Report this comment


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