We responded to the new requirements of a variety of automobile manufacturers by developing a series of extrusion compounds in subtly different gradations. They differ primarily with regard to flexibility and burst pressure and, in some instances, low-temperature impact strength. Their barrier effect to hydrocarbon permeation can also be custom-modified. The strain at break used as a quality criterion by many automobile manufacturers for their pipes depends primarily on the processing conditions and calibration procedure. When the extrusion process is properly executed, these values are easy to achieve.
Most of the VESTAMID® molding compounds designed for this application are suitable for both gasoline and diesel fuels. To keep up with increasing engine compartment temperatures, especially in vehicles made in Europe, we have also designed high-temperature resistant compounds. These compounds, such as VESTAMID ® LX9008 and VESTAMID® LX9013, are specially designed for use in either gasoline or diesel systems, and should be used only in the intended system.
MULTI-LAYER TUBing SYSTEMS REDUCE HYDROCARBON EMISSIONS
In the late 1980s, Europe and the United States began developing fuel lines with multiple layers. The impetus for the new design came from the increasing stringency of the requirements by the U.S. agencies CARB and EPA for reducing hydrocarbon emissions from the use of motor vehicles. Compared to monowall tubing, multi-layer tubing displayed reduced fuel permeation by 1 to 2 orders of magnitude.
Recently, the demand for conductive fuel lines has become increasingly important. The use of conductive plastic tubes for supply and return lines has become mandatory for U.S. car manufacturers, but Japan and Korea, as well as individual manufacturers in Europe, are also following this trend. The technical requirements and conditions for this are described in detail in SAE J1645.
High Performance Polymers has not only responded to the increased requirements but developed pathbreaking new combinations of materials. Our compounds are optimized so that they can be extruded at speeds comparable to those of monowall tubing. Because certain multi-layer designs use no adhesion promoters and can be fabricated nearly without having to change the usual monowall tubing technology, the technical expenditure required to begin producing multi-layer tubing is minor. Our wide range of compounds for multi-layer tubing also allows us to develop special customized systems.
Low-extraction multilayer tubing
With the multilayer tubing systems (MLT) 4800 and 4900, Evonik responds to new requirements in the automotive industry – low extractable fuel line systems. Both systems with inner layers of low extractable VESTAMID® polyamide offer significantly reduced levels of extractable substances.
TIGHTLY SEALED JOINTS WITH VESTAMID® QUICK CONNECTORS
Quick-connect fittings ensure fast, cost-effective connection of fuel lines. Our product range includes reinforced and non-reinforced VESTAMID® compounds, which are also available in electrically conductive variations. Conductive connecting elements are increasingly required in the United States and Japan.
For more temperature-resistant fuel lines, we offer appropriate connector compounds based on polyamide 612. Molding compounds for welded connectors are also available; tightness is increased through a substance-to-substance bond of the fuel line and bonding agent.
The polyamide 612 compounds of our VESTAMID® D line are also a choice material for the production of retainers, which are used in many quick-connect fittings.
In addition to quick connectors, various tube branchings and valves for fuel line systems are also made from VESTAMID® . More special types of compounds in addition to those found in the table are available upon request.
FUEL FILTER END CAPS MADE OF VESTAMID® ALSO ENSURE TIGHTNESS
Resistance to fuel is the primary requirement of fuel filters. In addition to outstanding resistance, filter end caps made of VESTAMID® L1723 also offer excellent flexibility. With the appropriate design, end caps serve as sealing elements, eliminating the need for O rings. They also weld well to the filter material, which is typically made from VESTODUR® X7065, a polybutylene terephthalate molding compound from Evonik.
MORE THAN JUST MATERIALS DEVELOPMENT
We have collaborated on international committees for developing and improving specifications and test procedures for lines and assemblies since our work on compounds for line systems began. Based on this knowledge, we provide services such as fuel permeation measurements and test procedures for determining layer adhesion to assist customers with their development projects. Customers also have our equipment for manufacturing and testing straight or corrugated multi-layer pipes at their disposal.