Low extractable fuel line

Jon Lawson

With the multilayer tubing system (MLT) 4800, provider of polyamide 12 for multilayer plastic tubing systems, Evonik Industries, responds to new requirements in the automotive industry – low extractable fuel line systems. The new MLT 4800 system with an inner layer of low extractable VESTAMID polyamide 612 offers significantly reduced levels of extractable substances.

Alcohol containing fuels and lower fuel consumption

The use of fuels that contain alcohol, for example biofuels containing ethanol, can lead to the extraction of substances from the inner walls of conventional gasoline lines. Under certain extreme conditions these substances can clog the nozzles in new, sensitive fuel systems, which use small-diameter nozzles to create an atomised spray of gasoline and air for fuel injection in order to decrease fuel consumption. To reliably counteract this, the automotive industry is looking for new fuel line materials with significantly reduced extraction.

Existing series expanded

For many years, Evonik has been offering its MLT 7440, a conductive system that fully meets the requirements. The new MLT 4800 now supplements it with a non-conductive system. It is based on the MLT 4300, with an outer layer of VESTAMID polyamide 12 and a barrier layer of ethylene vinyl alcohol (EVOH) to prevent fuel permeation. In the MLT 4800, however, the PA6 inner layer of the proven system 4300 is replaced by a newly developed, low extractable VESTAMID polyamide 612, which meets the requirements of automobile manufacturers. The mechanical characteristics, chemical resistance, and permeation behaviour are on the same level as the MLT 4300, which is the currently most used MLT in Europe.

VESTAMID has been in use by prestigious automobile manufacturers for more than 50 years. In addition to molding compounds for monowall applications, Evonik has also developed various multilayer tubing systems with different barrier layers. VESTAMID polyamide 12 and polyamide 612 are the world's most widely used polyamides for tubing systems in automobiles.