A Material Compatibility Study of Automotive Elastomers with high FFA based Biodiesel

Application of renewable fuels and changes in fuel composition often create many trouble in gaskets, seals, elastomers and O-rings in the engine fuel system. In a CI engine fuel system, fuel comes in touch with different elastomeric components. The compatibility of automotive fuel system components like seals, gaskets and hose materials using conventional fossil based diesel has long been recognized and documented but there is concern over the use of elastomeric materials with biodiesel. Based on these concerns, a study of compatibility of Natural rubber, Nylon and EPDM (Ethylene Propylene Diene Monomer) with biodiesel and diesel was carried out. High FFA oil, which is a byproduct of edible and non-edible oil refineries, is available at low price and in considerable quantities at vegetable oil refinery sites. In the current study, high FFA oil is synthesized into biodiesel by two step process i.e. esterification followed by transesterification. The methyl ester content of biodiesel is determined by GCMS. The fuel properties of the produced biodiesel were found to be comparable with that of biodiesel specifications. Static immersion test in biodiesel and diesel has been carried out as per SAE J1748 standards. This paper aims to characterize the compatibility of Natural rubber, Nylon and EPDM, commonly encountered in the automotive fuel system in diesel engines. Static immersion test in B100 and diesel fuel was carried out at 55±2 °C (SAE J1748 para 5.2) for 500 hours. Fuels were replaced weekly as suggested in SAE standard. Before the immersion test, mass measurements and visual inspection were recorded. Before and after immersion, comparative behavior was investigated by weight loss, volume change, hardness; tensile strength measurements. Changes in surface morphology were studied by Scanning Electron Microscopy. It was found that natural rubber showed less detrimental effects while significant detrimental effect on EPDM and Nylon was observed.