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When hydrocarbon emissions are measured for conformance testing of a vehicle's fuel and vapor handling systems, the test used is the Sealed Housing Evaporative Determination (SHED) procedure. Flame Ionization Detection (FID) techniques are used for those measurements. During development of individual fuel/emissions systems components, however, recirculation procedures described in SAE J1737 are utilized to determine emissions (adsorbancy measurements of permeation are used). The platform engineer needs a correlation between values out of both procedures and to be able to estimate the emissions of the fuel/emission system of his platform based on the lab values available for the individual components. The study was done using alcohol-containing fuels. In addition to permeation measurements for 3 different temperatures, an understanding of speciation of the fuel constituents is necessary.

Nylon 12 resins have been utilized for liquid fuel lines in automobiles for more than 25 years. This resin has proven its suitability in monowall tubing in the chassis environment and in contact with normal fuels. The development of more aggressive fuels (mostly those containing alcohol) and the establishment of new hydrocarbon emission standards by various government agencies have changed this. In response to the changing situation, multilayer tubing has been developed in order to improve the properties of the nylon 12 tubing, primarily the permeation resistance. Hüls has developed two different constructions, both of which contain a fuel-resistant barrier layer in the wall of the Nylon 12 tubing. One utilizes a barrier layer of a specialty polyester resin with good bonding to the outside and interior layers of Nylon 12 without use of an adhesive. The other utilizes a PVDF resin bonded to the Nylon 12 by an adhesive layer.

With the development of pressurized fuel systems, the evolution of vehicle designs, and the increasing variety of fuels available, the environment an automotive fuel system encounters is becoming increasingly difficult. A fuel line made of Nylon 12 can meet all environmental and flexibility requirements of the fuel system. As a result, Nylon 12 is the most widely used, nonmetallic fuel line material. For a thermoplastic fuel line, dimensional increases (mostly length change) can vary widely from the swelling caused by the different fuels encountered. Nylon 12 is affected the least of all the nylon resins. The use of plasticizer further decreases the swelling that can occur with Nylon 12, but does not eliminate the dimensional changes completely. A method has been devised to produce Nylon 12 tubing that has no length change, even in fuels that are very aggressive chemically.

The paper outlines three emerging issues that are currently affecting material selection decisions throughout the world: ecology, increasing government regulations and consumerism, and the energy shortage. Contents of the paper explain and discuss an analysis regarding the need for automotive weight reduction and the concomitant effects of weight reduction on fuel economy.