Diesel engine fuel hose return line is considered as a low pressure line and consists of two layers. The inner layer is used to carry the excess fuel, thereby hose material shall have resistance to fuel and its residues. The outer layer is used to protect inner layer from heat, ozone and oil spillage, thereby outer cover material shall have resistance against the heat, ozone and engine oil.
Currently NBR PVC, NBR and FKM materials have been used as inner layer materials in diesel engine fuel hose outer cover application, according to service temperature. Halogen contained CSM material has been used for outer cover application and the production of CSM material was withdrawn by one of the major manufacturer recently.
Current global challenge is to use environment friendly material in vehicle components to make hazardous free environment. To replace CSM material, which contains Halogen, the available options are CPE, CR, HNBR and AEM materials. CPE and CR contain Halogen but HNBR and AEM do not. HNBR and AEM can be used in high temperature application however they are more expensive than other materials. Considering all these factors a halogen free and viable synthetic elastomer blend was developed to replace CSM material.
It is well known that blends of elastomers containing polar groups are not compatible with hydrocarbon synthetic elastomers. Hence, the challenge lies in blending of these materials. Attempt was made in blending of NBR/Ethylene based synthetic elastomer and XNBR/Ethylene based synthetic elastomer to meet the requirements of fuel hose outer cover. Prior work has resulted in inferior and inconsistent mechanical properties and latter work has led to successful blending of polar and non polar material thereby mechanical properties were achieved.