Validation of the Localized Fire Test Method for On-Board Hydrogen Storage Systems

The localized fire test provided in the Global Technical Regulation for Hydrogen Fuel Cell Vehicles gives two separate test methods: the ‘generic installation test – Method 1’ and the ‘specific vehicle installation test – Method 2’. Vehicle manufacturers are required to apply either of the two methods. Focused on Method 2, the present study was conducted to determine the characteristics and validity of Method 2. Test results under identical burner flame temperature conditions and the effects of cylinder protection covers made of different materials were compared between Method 1 and Method 2. The results indicated that, where the cylinder had no protection cover and the burner flame was regulated under identical propane gas flow rate conditions, Method 2 registered higher burner flame temperatures than did Method 1. However, when the burner flame temperatures were set identical, the cylinder’s surface temperature and the time of thermal pressure relief device (TPRD) activation were both found practically identical between the two methods. Where the cylinder was protected with a steel cover, Method 2 gave lower cylinder surface temperatures during the TPRD pre-activation period. Where a thermoplastic (polypropylene) protection cover was installed, under a localized fire the cover melted into pools and drips of burning liquid and spread fire to other areas of the cylinder, thus leading to an expedited activation of TPRD. Nevertheless, the advantage of expedited TPRD activation varies according to how and where fire pools are generated by a melting thermoplastic cover in relation to the propane burner, it is necessary to examine the melting and burning behaviors of flammable protective devices in real world fire situations.