Comparative Evaluation of Automotive Fuel Tanks in General Accordance with ECE R34.01, Annex 5 Section 5.0 “Resistance to Fire” 2005-01-1561

The primary objective of this study was to compare the performance of “new” plastic fuel tanks vs. “aged” plastic fuel tanks when subjected to the standard fire exposure test described in ECE R34.01, Annex 5 Section 5.0 “Resistance to Fire.” The program also included a comparison of failure modes of plastic vs. metal fuel tanks when subjected to a simulated post-crash pool fire. The “new” tanks were purchased from the OEM suppliers (not weathered or pre-conditioned with fuel). The “aged” tanks were obtained from vehicles that were operated in a warm climate and considered to be weathered and fully conditioned with fuel. Three vehicle types, representing three fuel tank shapes and installations, were evaluated: 1.) “thin profile” tank, typical of front wheel drive cars with the tank mounted on the underbody near the rear seat area and in front of the rear axle; 2.) “square profile” tank, typical of SUV's with the tank mounted behind the rear axle; and 3.) “long profile” tank, typical of vehicles with the tank mounted inside the frame rail and in front of the rear axle or rear suspension. The results indicated that the effects of aging did not significantly impact the performance of the fuel tanks in the fire exposure test. The test results also demonstrated how design variation and installation location affects the performance during the standard fire exposure tests. The results from the simulated pool fire tests conducted on the steel and plastic fuel tanks indicated different modes of failure. Plastic fuel tanks failed by developing leaks under minimal pressures, whereas steel tanks develop vapor pressure that rapidly release when the tanks integrity is compromised.