The automotive sector has enhanced the use of plastics in fuel tanks. An increasing trend of plastic fuel tanks in automobiles is indicated in the fact that all European automobiles have almost fully converted to these plastic fuel tanks. One estimate suggests that 92% of the cars of European origin have plastic fuel tanks. North American automobiles are lagging behind with 75% of the automobiles having plastic fuel tanks. Automotive sector in the Asian region, however, is far behind its Western counterparts. This could possibly be attributed to the smaller number of cars produced in different parts of Asia as compared to Europe and North America. The use of plastic fuel tanks is uneconomical at lower production level of an individual automobile company. Mostly blow moulded or injection moulded multi layers HDPE fuel tanks are quite common. Significant developments have been done by the industry to meet the recent emission standards.
Compared with existing rubber and steel fuel lines, plastic fuel lines are lighter in weight, lower in cost and often less permeable. They are also available in many colors, which make it easier to place, track and connect fuel supplies. However, the automobile companies are very slow to adapt the plastic lines that convey fuel from tank to engine compartment. The slower pace stems from concerns by auto companies over the ability of plastic fuel lines to meet strict air emission standards, and to resist electrostatic discharges (ESDs), which could ignite flammable fuels. Automakers also need to be convinced that fuel lines made of plastics can withstand the impact of crashes at low winter temperatures and can resist degradation from alcohol fuels. But polymer suppliers and Tier One auto manufacturers have developed new fuel line materials and designs which they believe can meet these challenges.
The most common polymer used in plastic fuel lines is polyamide. It is often combined in multilayer structures with fluorocarbon polymer barrier resins. Another low-permeability material that has been paired with polyamide in multilayer structures is polybutylene naphthalate (PBN). Aliphatic polyketones have also been promoted as fuel line materials. Some polymide based fuel line formulations include low levels of carbon nanotubes, which enhance their ESD properties without harming their physical properties. New ways for improving the ESD properties of fuel lines are also emerging. The typical approach for making a plastic fuel line static dissipative is to add graphite fibers to the resin formulation. But this can degrade the polymer's properties, particularly its impact strength. A newer practice is to make fuel line resins conductive with much smaller particles called carbon nanotubes. One supplier of these micron-size carbon additives, offers masterbatches of nylon 12 containing just 2-3% loadings of nanotubes. At these levels, the additives reduce the static discharge properties of the polymer to safe levels, but do not affect its physical properties.
Complying with increasingly stringent anti pollution regulations is the biggest challenge faced by developers of plastic fuel lines and other plastic fuel components such as tanks, pumps, vapor recovery systems, filter pipes and fuel rails. Of most concern to the global auto industry, are regulations in the U.S. state of California that limit the levels of hydrocarbons auto fuel system can release into the air. Among them are the ZEV (zero emission vehicle), PZEV (partial zero emission vehicle), and the CARB (California Air Resource Board) LEV (low-emission vehicle) II standards. Some of these rules have already taken effect; others will be phased in over the next few years. Because California has traditionally set the pace for air pollution regulations in the rest of the U.S. and elsewhere, most of the world's car manufacturers are striving to meet the standards in that state.