Wherever aggressive biodiesel and alcohol additives are utilised in motor fuels, it poses particular problems associated with unstable chemistry during production, blending, transportation and dispensing of such fuels. Relative to other fuel components, biodiesel is subject to degradation, particularly when combined with contamination as the increasingly aggressive fluid progresses through a production and distribution network.
Contaminated fuels can attack hydrocarbon rubbers such as nitrile that are commonly used as the sealing medium for hoses, gaskets and O-rings used throughout the fuel handling processes. An additional problem of permeation is also encountered with nitrile rubbers where fuels incorporate ethanol. This can lead to the potential loss of expensive fuel and the emission of dangerous VOC’s.
As biodiesel moves through the production/distribution network, it is increasingly contaminated with water and microbes, becoming more acidic in the process, and with detrimental effects on the nitrile rubber, which can swell and soften. This results in diminishing seal strength and hardness, leading to eventual seal failures. Viton fluoroelastomer compounds from DuPont have successfully provided the ability to resist and withstand such attacks from a growing range of solvents and fuels. Viton has been tested with US ethanol/gasoline blends, together with butanol. Viton is also widely recognised for outstanding performance at elevated temperatures, as well as its suitability for conditions of -50°C to -65°C with certain biofuels when used for static sealing applications. However, it is important to assure sealing products are ‘made with genuine Viton’, with the appropriate material and formulation fluoroelastomer supplied for each application.