Joseph Walker, global director, Advanced Materials Development for Freudenberg-NOK Sealing Technologies, will present the technical findings of the study at the SAE 2014 Commercial Vehicle Engineering Congress (COMVEC) in Rosemont, Ill., 7 Oct.

The study tested the effects of biodiesel fuel oil diluted mixtures on 15 common sealing materials including silicones, polyacrylate polymers, acrylonitrile materials, fluorocarbon rubbers (FKM) and others. A performance baseline was established and the materials were then immersed in biodiesel fuel-oil blends and tested for retention of specific seal properties as well as dimensional stability.

We saw a need to study how our static and dynamic seals would behave in diluted engine oil. What this study revealed is 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, tried 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.

—Joseph Walker

While industry studies that examine the impact of oil-fuel dilution on lubricants exist, this is the first time a company has undertaken efforts to understand how oil-fuel dilution affects sealing elements, Walker said.

This comprehensive study was designed to close that gap. 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. And the dilution of the engine oil with biodiesel fuel does have pronounced effects on both lubricant and seal life.

—Joseph Walker

The issue is particularly important in the construction industry where heavy machinery is being constantly leased and operated for long periods between maintenance cycles, noted Joel Johnson, senior segment director, Mobile Machinery, Freudenberg-NOK.

The Freudenberg-NOK study was launched in response to published accounts highlighting concerns associated with diluted oil in heavy machinery.

As the large earth moving equipment and other heavy machinery becomes cleaner by using biodiesel fuels, manufacturers are going to experience more motor oil contamination in their engines from this fuel. 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.

—Joseph Walker

Freudenberg-NOK Sealing Technologies is the Americas joint venture between Freudenberg and Co. in Germany and NOK Corp. in Japan. Freudenberg-NOK is a leading producer of advanced sealing technologies for a variety of markets including: aerospace; agriculture; appliance; automotive; construction; diesel engine; energy; food and beverage; heavy industry; and pharmaceutical. Founded in 1989 under the legal name Freudenberg-NOK General Partnership, Freudenberg-NOK is headquartered in Plymouth, Mich. and operates more than 20 facilities across the Americas.