VESTAMID® IN Other Line Systems
Versatile aND all around
In addition to fuel lines, VESTAMID® compounds are also used to produce other air and liquid-conveying lines. Depending on its function and the environment in which it occurs, each application emphasizes different properties, so we adapt our compounds to meet specific, individual requirements.
From clutch to Air suspension
For the clutch line system, we offer VESTAMID® L compounds with particularly high resistance to engine oil, aggressive chemicals, and hydraulic fluids. Their low water absorption trough diffusion ensures that the function of the hydraulic fluid is not impaired. At high internal pressures, the lines display only minor changes in volume—especially at high temperatures—which means that the clutch pedal is subject to uniform operating forces and pressure points.
Vacuum brake booster lines are exposed to temperatures up to approximately 150°C. They are placed between the brake booster and the engine, and they must have the necessary flexibility and low-temperature impact strength. In addition to generally good resistance to attack by chemicals and the ability to withstand stress cracking by air-gas mixtures, both internally and externally, good resistance to ozone is important—conditions that VESTAMID® L and E compounds are custom-tailored to satisfy entirely.
Steel tubes for hydraulic brake systems in passenger cars and light utility vehicles are fitted, for better corrosion protection, with a 0.15 mm thick extrusion coating of VESTAMID® L. This must, of course, adhere well to the metal and possess good low-temperature impact strength against stone impacts, not to mention feature good chemical resistance to de-icing salt and salt-spray.
Other things being equal, VESTAMID® E corrugated tubes with quick connectors are more leakproof, more durable and less costly to install than EPDM hoses for windshield washer systems. Because windshield washer fluids have become harsher as a result of the change from isopropanol to ethanol as an antifreeze, we also offer VESTAMID® L and D compounds developed specially for this application.
To support engine performance, tubes located near the engine block have to supply air or air-gas mixtures. To supply air, VESTAMID® L tubes are invariably used if other polyamides fail to have the requisite flexibility, low-temperature impact strength, and heat aging resistance.
Because air brake lines are exposed under the entire frame of heavy and medium utility vehicles, resistance to flying stones is essential. VESTAMID® L is distinguished here by its high impact strength and low-temperature impact strength. Even construction site vehicles can always rely on their brakes. At the same time, the lines are flexible enough that they can be moved freely between the assemblies and coiled into spirals. Nowhere is the excellent chemical resistance of polyamide 12 more clearly apparent than in the area of metal connections: the zinc chloride in de-icing salt does not cause stress cracking in tubes made of VESTAMID® L. Our advanced compounds also meet the more stringent requirements for materials used to produce high burst pressure-rated air brake lines. In Europe, VESTAMID® L lines like these are used primarily in tractors, while VESTAMID® L tubes that meet the more traditional pressure requirements are used for trailers and coils.
A feature that has long been widely used in utility vehicles is now being increasingly offered by manufacturers in passenger vehicles to increase comfort and safety: electronically controlled balancing of the vehicle on the road by means of an air suspension system . We have adapted the VESTAMID® L tube and connector system, already proven in trucks, to the requirements of passenger cars: standard compounds for flexible air suspension lines that are resistant to pressure and zinc chloride and that feature low-temperature impact.
New lines for cool number crunchers
Line systems made from VESTAMID® polyamide 12 and polyamide 612 compounds are far superior to the traditional reinforced or unreinforced EPDM hoses or metal tubes for circulating coolant between the radiator, pump, heat exchanger, and coolant expansion tank. They are:
thinner, because of their strength
not prone to fatigue failure
quickly and easily joined via quick connectors, and therefore more economical
low temperature impact-resistant
resistant to flying stones
chemical resistant, therefore not subject to corrosion
able to withstand brief external temperature loads of up to 150° C
highly resistant to heat aging
good resistant to burst pressure
Monotubes for ventilation systems
In the cooling water ventilation system—for example, between the coolant expansion tank and the radiator—the hot ethylene glycol-water mixture does not flow through the lines continually. Monotubes made from the hydrolysis-stabilized compounds VESTAMID® LX9008 (PA12) or VESTAMID® DX9304 (PA612) are well suited for this area, because they absorb little of the solution and therefore do not swell. Multi-layer tubes, as described below, are also suitable for this application.
Multi-layer tubing for coolant lines
Coolant lines that constantly come in contact with hot coolant call for multi-layer tubing. For this application, Evonik has developed VESTAMID® based multi-layer tube (MSR) systems that are already being used by renowned manufacturers.
With diameters of up to 30 mm and wall thicknesses of 1 to 1.5 mm, the systems of the MSR 8000 series are structured with three layers:
The inner layer consists of polypropylene customized to the application.
On top of this sits an adhesion-promoting layer.
The outer layer is made of high-grade VESTAMID® specialty polyamide.
Because of a modification carried out at the molecular level, the compound for the MLT 8000.3 provides higher flexibility without the need to add a plasticizer. The MLT 8000.1, on the other hand, features higher bursting strength, especially at high temperatures. This allows the user to select a system tailored to his or her specific requirements.
Coating protection against corrosion
Steel and aluminum alloys are used in applications that do not require the flexibility of plastic tubing or that specifically call for metal tubing. A coating of VESTAMID® X7377 or VESTAMID® LX9001 can improve the corrosion and flying-stone resistance of this metal tubing.
VESTAMID® FoR ADBLUE® lines in the SCR SYSTEM
To restrict environmental emissions from road vehicles, the European Parliament has further tightened the Euro 5 and Euro 6 standards as regards emission limits for light road vehicles with diesel engines, particularly as regards particle and nitrogen oxide emissions. In order to meet the latter requirement, car makers are currently developing systems for selective catalytic reduction (SCR) of nitrogen oxides. The reducing agent here is a 32.5% aqueous solution of urea, registered by the VDA (the German Association of the Automotive Industry) as AdBlue® . At temperatures above 60°C, AdBlue® reacts with water to yield carbon dioxide and ammonia; the latter in turn reacts with nitrogen oxides, forming water and nitrogen and thus reducing the emission of nitrogen oxides by about 90%.
AdBlue® places the following high demands on the catalyst feed lines:
chemical resistance to urea and ammonia as well as to any gas mixture flowing back from the catalyst
hydrolytic resistance up to at least 60°C, the maximum temperature of the urea solution
high impact resistance and elasticity in the cold because AdBlue® freezes with expansion at -11°C
Evonik helps car makers develop their systems by offering a variety of products for systems that have various requirements. All VESTAMID® molding compounds were subjected to a recirculation test with AdBlue® at 60°C and 80°C (for external air temperatures of 40°C and 50°C, respectively) over a period of 5,000 hours to detect any changes in their mechanical properties. All of the tested grades have excellent values for strain at break and breaking strength, bursting strength, and, in particular, low-temperature impact strength at -40°C.
Of all the grades tested, VESTAMID® LX9008 best satisfied all the requirements. VESTAMID®L2140 and X7293 are already being used in SCR systems.
Resistance to AdBlue®
Resistance to exhaust gases
AdBlue® frost resistance