Study on Effects of Methanol on Material Compatibility of a Fuel Supply System in a Spark Ignition Engine 2021-01-1189

The components of fuel supply system of a methanol fuelled spark ignition engine come in direct contact with the fuel. Corrosive nature of methanol affects the material properties. The present study deals with the compatibility of various materials of the fuel supply system including elastomers (nitrile, polyvinyl chloride (PVC) nitrile, chloroprene, natural rubber and ethylene-propylene-diene monomer (EPDM)), aluminium and fuel filter (outer tin coated circular plate and paper) with methanol. The specimens of the parts of the fuel supply system were immersed in methanol for a period of ninety days under atmospheric conditions. The properties of the specimens such as physical changes using scanning electron microscope (SEM) image of the surfaces and mechanical properties including tensile strength and strain at break were studied. It was observed from the images that the coating over the circular plate of fuel filter eroded while elastomers developed a whitish coat on their surface. SEM images indicated that surfaces of EPDM, chloroprene and natural rubber were damaged significantly. Swelling of nitrile, chloroprene and natural rubber took place due to diffusion of methanol inside their structures. SEM image showed mild deterioration of aluminium surface. Furthermore, tensile strength of natural rubber, chloroprene, nitrile and PVC nitrile decreased by 29.3%, 59.8%, 31.2% and 33.2% respectively. Decrease in strain at break was significant with chloroprene, nitrile and PVC nitrile rubbers. A notable conclusion emerged from the study that EPDM performs satisfactorily with methanol since deterioration of its mechanical properties and swelling was negligible.