This paper describes experiments within a simulated refuelling station forecourt environment, with dispenser units and a dummy vehicle. The experiments range from a so-called ‘worst-case scenario’ where the vehicle and dispensers are enveloped by a pre-mixed hydrogen-air cloud, to a high-pressure leak representing an uncontrolled full-bore failure of a vehicle refuelling hose, and finally a similar failure of the refuelling hose where the release of hydrogen is controlled by the safeguards within the dispensing system.  In all cases an electric spark was used to ignite the flammable cloud.  Measurements were made of the explosion overpressure generated, its evolution with time, and its decay with distance.

The results reported provide a direct demonstration of both unrealistic worst-case conditions, and what might actually happen in practice in the very unlikely event of a full-bore hose failure and the presence of a source of ignition.  These results will be used in the development of codes and standards to ensure that hydrogen-refuelling stations meet the highest standards of safety.