Fire Safety of Compressed Hydrogen Cylinder and Hydrogen Fuel Cell Vehicle

Abstract

This paper reports research outlines and safety issues from an experimental study conducted recently by Japan Automobile Research Institute on the fire safety, including existing safety measures, of hydrogen fuel cell vehicles (“HFCV”). One of the concerns about the fire safety of vehicles equipped with a compressed hydrogen cylinder is the proper presence and function of a pressure relief device (“PRD”) designed to release hydrogen gas from the cylinder at the detection of a fire. Since bursting energy in a 70-MPa high pressure compressed hydrogen cylinder can reach 2.4 - 4.2kg in TNT equivalent in case of PRD failure, every necessary step must be taken to prevent PRD malfunction. If the PRD of a 35-MPa hydrogen cylinder is activated, an upward flame of as high as 10m is generated for about 1 minute. However, this short-lived flame is not thermally sufficient for adjacent vehicles to catch fire; HFCV on fire are equivalent with CNG and gasoline vehicles on fire in terms of their thermal impact on surroundings. Furthermore, HFCV fire can be extinguished by an spraying of water while dispensing with any special fire fighting measures.