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Joe Walker, Global Director, Advanced Materials Development, Freudenberg-NOK Sealing Technologies

The good, the bad, and the biodiesel

With the cost of fossil fuels continuing to rise as the quantity is depleted, there is a strong driver for continued investment in renewable fuel sources. One such approach is the use of plant-based renewable materials to augment conventional fossil fuel for diesel applications. This method has given rise to the biodiesel fuel industry.

Studies have documented fuel-oil dilution issues in diesel applications and found that the presence of biodiesel in engine oil reduces the life of the oil as well as its effectiveness. Other negative effects include reduced oil viscosity, increased engine wear, acid formation leading to corrosion, and low oil pressure.

As part of the SAE 2014 Commercial Vehicle Engineering Congress last October, I presented a study that we conducted at Freudenberg-NOK regarding the effects that biodiesel fuel-oil blends have on common sealing elastomers in heavy agricultural and construction equipment, something many manufacturers might not necessarily be thinking about.

We realized that if we understood how these biodiesel fuel oil mixtures impacted elastomeric materials on a molecular level, we could determine which ones would perform best and longest for our customers and require the fewest seal replacements.

In the construction industry, where heavy machinery is being constantly leased and operated for long periods between maintenance cycles, the issue is particularly important. By offering our customers elastomeric seals that have been specifically engineered and validated to operate flawlessly in a biodiesel fuel environment, they can be assured that their machinery will experience fewer mechanical failures and downtime due to seal issues.

As the large earthmoving equipment and other heavy machinery become cleaner by using biodiesel fuels, manufacturers are going to experience more motor oil contamination in their engines from this fuel. They must consider the potential consequences. Biodiesel fuels have a much higher boiling point and the fuel is miscible with the engine oil. This means more fuel remains in the oil during use and this diluted oil mixture impacts engine and component operation.

With agricultural and construction manufacturers increasingly accommodating the use of biodiesel fuels in their vehicles, components used to seal engines and transmissions against contamination and leaks must be made of tested, validated elastomeric materials that withstand unique operating conditions or they will prematurely fail.

The dilution of the engine oil with biodiesel fuel does indeed have pronounced effects on both lubricant and seal life. In particular, our study revealed that there are specific grades of fluoroelastomers—those whose molecular architecture is designed for specific types of crosslinking by organic peroxides—that offer the most robust sealing solutions to issues with biodiesel blends. We already have these materials validated and in use in our products. These materials are being used to design seals that will not be harmed by biodiesel fuel-oil blends and will require replacement less often.

Manufacturers must pay close attention to the fuel they are putting in their engines and the effects that it can have on a variety of other things. Biodiesel fuel is certainly a viable supplement for traditional fossil fuels, as long as manufacturers are making the necessary changes in equipment to accommodate these new types of fuels.

Joe Walker, Global Director, Advanced Materials Development, Freudenberg-NOK Sealing Technologies, wrote this article for SAE Off-Highway Engineering.

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