Seal Material For Biodiesel

Biodiesel Seal MaterialArticle re-posted with permission from Parker Hannifin Sealing & Shielding Team.  Original content can be found on Parker’s Blog.

Gallagher Fluid Seals has long been a supplier of seals to the energy, oil and gas industry.

From sealing applications in the renewable energy sector (hydroelectric, solar, wind, and thermal) to more traditional fossil fuel exploration and extraction in extreme environments, we’ve pretty much seen it all.

One of the newer products energy/oil/gas sector products we’ve been working with is biodiesel.  And Parker, one of our most trusted sealing partners, has compounds made specifically for biodiesel.

With the price of oil at rock bottom, it seems that no one is interested in biodiesel these days. But don’t think that cheap oil is a long-term solution. At some point, the price of oil will rise and biodiesel will once again be making the news.

Diesel engine fuel systems use fluorocarbon elastomers almost exclusively. Most systems use the traditional Type 1, or copolymer, grade of fluorocarbon like Parker compound VM100-75. It’s the most cost effective of all the fluorocarbons, has excellent compression set resistance, and does a wonderful job with diesel fuel. It’s not as good for low temperature as the low temperature (Type 3) fluorocarbon materials, but diesel fuel and biodiesel both gel at low temperatures, so this limitation doesn’t pose a real-world leakage risk.

Fluid compatibility

Through extensive testing, we’ve found that the “old standby” fluorocarbon compounds do an adequate job in the common 20% biodiesel blends (B20) as long as the application temperature stays below 100°C.

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However, as the temperature rises and the concentration of biodiesel increases, elastomer compatibility becomes more of a concern. In addition, biodiesel absorbs water and begins to break down over time, and this accelerates the compatibility issues. From our testing, it’s clear that water is a significant “bad actor” when it comes to volume swell. Interestingly, methanol, potassium hydroxide, and higher acidity were not as aggressive to V1164-75.

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The solution is to look at higher performance fluorocarbon compounds. The improved low temperature fluorocarbon compounds also provide much more stability in biodiesel as the temperature increases and as the biodiesel becomes increasingly contaminated. Surprisingly, the GFLT-type of low temperature fluorocarbon (Parker compound V1163-75) did not perform as well as the other low temperature grades.

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Of course, these are not the only possible options for use when choosing biodiesel seal material. Other materials may be considered, but they were not evaluated in this particular study.

Low temperature performance

O-rings can typically seal to about 8°C below their TR-10 value in static applications and down to their TR-10 value in dynamic applications. The goal in the diesel engine industry is to seal at -40°C without leakage. To date, that has not been an issue for Type 1 FKMs in diesel and biodiesel applications.

In this case, the best materials for biodiesel in this testing, Parker compounds VG286-80 and V1289-75, also offer improved low temperature performance.

 

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Type 1 fluorocarbon compounds like VM100-75 will continue to be the low cost solution for sealing diesel and biodiesel. In fact, these materials have been used successfully in ongoing multi-year customer field trials without fuel leakage. However, Parker’s low temperature (Type 3) fluorocarbon compounds VG286-80 and V1289-75 offer significant improvements in compatibility with wet and contaminated biodiesel, as well as an additional safety factor for low temperature function.

For more information about biodiesel seal material from Parker, please contact Gallagher Fluid Seals.