Shell for Fuel Tank Stops Emissions.

Anew blow molded, double-walled fuel-tank cover that improves resistance to vapor permeation is proposed as a solution to stiffer antipollution requirements for U.S. cars. Developed by the German parent of SIG Kautex (formerly Krupp Kautex), Edison, N.J., the coextruded CVR (Complete Vapor Recovery) tank cover reportedly complies with new hydrocarbon emission test standards being drafted by the U.S. Air Resources Board. The new standards would lower the maximum emissions from 2 g to 0.5 g per test for 15 years or 150,000 miles. SIG Kautex is aiming for emissions lower than 0.03 g with its tank-cover design.

The CVR cover is welded to the upper part of the fuel tank. It creates a chamber between the cover and the tank where hydrocarbon vapors can collect and be recovered through an activated-charcoal filter. The shell covers the functional parts of the tank (pump flange, fittings, breather and vent lines, valves, sensors, filter, and tank seam), eliminating the need for complex diffusion barriers.

The tank cover can be blow molded inexpensively as a thin-walled, lightweight part. It can have up to six layers, similar to the tank itself, utilizing an EVOH barrier layer and reclaim material.