Dazo Water Fuel Technology

2.3.2 Fires and Explosion

Hydrogen has higher energy content (per pound) than diesel fuel and is very reactive, which results in a very vigorous fire. However, the buoyancy of gaseous hydrogen means that it rises rapidly and diffuses quickly, resulting in a very vertical and localized flame. Hydrogen fires also tend to burn out fairly quickly. By contrast, diesel fuel and gasoline fires tend to burn longer and spread over a much larger area, as the liquid fuel puddle expands.

There is virtually no risk of a thermal “explosion” of hydrogen stored in a closed tank unless oxygen has been allowed to enter the tank during fueling operations, which is virtually impossible if the fueling system has been designed properly. Hydrogen gas that leaks into an enclosed space, whether on a vehicle or in a building, can create an explosive mixture, depending on the volume of hydrogen relative to the volume of air in the space.

Diesel fuel is not very volatile, and the risk that accumulated vapors will result in an explosion is small, even for large leaks. Gasoline, however, is very volatile and vapors from leaks can create the risk of an explosion if they collect in an enclosed space on the vehicle or in a building.