A methodology to create limit sample definition for part level evaluation of rubber hoses to optimize the testing requirement

Various countries all around globe are adopting usage of alternate fuel to reduce dependency on fossil fuel in automotive application, to curb fast depleting fossil fuel and rising concerns of deteriorating air quality due to vehicular emissions. Govt. of India also took a big leap to switch over from 10% Ethanol blend gasoline (E10) to 20% Ethanol blend (E20) gasoline to improve air quality, boost farmers income by converting farm produce to ethanol and reduce imported crude oil dependency of nation. Fuel system components are safety critical parts and functional loss like leakage can lead to safety hazard. In general, sample preparation at worst conditions is done to evaluate system robustness. Need of the hour was to develop E20 compatible parts within limited span of time to meet government timelines. To develop an automotive fuel hose suitable to higher ethanol blend, fluorinated, carbon-based synthetic rubber, also known as FKM rubber as an inner material of fuel hose was planned for usage. To define bench level evaluation, limit sample definition was proposed to expedite the part evaluation in worst conditions wrt to part dimensional variations. The paper summarizes testing requirement for the product evaluation and its detailed testing requirements as defined in SAE J30, 1998. After due deliberation, a limit sample definition is made for each testing thus a relation between testing requirement and actual vehicle experience to minimize lead time to ensure worst case result examination for safety and performance. Keywords: FKM, E10, E20, Ethanol Blended gasoline, Limit sample.