Innovative Testing Device For Ultra-Low Fuel Permeation Systems 2001-01-3769
New regulations on Hydrocarbon (HC) emissions have set more stringent requirements for fuel systems evaporative emissions. This creates a need for developing new and more efficient material structures able to offer enhanced barrier properties to fuels. Such low levels of permeation rates have proven to reach the lower detection limits of most of the existing test equipment or methods, and have required the development of innovative techniques in order to characterize new materials or structures by measuring their permeability coefficients, or to be able to compare various constructions for components or sub-assemblies of the fuel system.
A new device has been designed and built in our Technology Center in Rastatt (Germany) and proves to offer an outstanding precision capability in measuring ultra-low permeation rates (less than 0.5 mg/day). Its operating process and the easy control on key input parameters offer a large flexibility in terms of measurement resolution and time. The system has been successfully adapted for intrinsic material permeability measurement and to component evaluation, ranging from small parts (valves, connectors, caps, …) to a full size tank (70 liters).
After reviewing existing techniques and devices used to measure permeation rates on fuel systems, the current paper will give a detailed description of the new process, precise the mathematical model applied to process experimental data and finally introduce some practical examples in various configurations.