During refuelling the main safety aspects are related to the risk associated with a potential ignition of a hydrogen leakage at the station or at the vehicle:
- A strict procedure for refuelling is available at the refuelling stations, which is displayed at the front of the refuelling station. The drivers are trained according to this procedure.
- During refuelling the bus is earthed by an earthing cable, to avoid sparks caused by static electricity.
- Leakage during refuelling would lead to hydrogen which would be directed to the roof top via the gas tight tube. In addition, the hydrogen would be detected by the bus and alarm would be given.
- When disconnecting the refuelling hose, some hydrogen can escape. However, only a small portion of hydrogen can be present in the pistol since the volume is small and the hydrogen is under atmospheric pressure. The overpressure inside the tanking pistol is released when decoupling the pistol from the bus. Hydrogen is vented to the roof.
A special 'Tools Kit' to used for common diagnostics of the fuel cell system is described by Ballard in this document.