A significant hydrogen leak occurred during refueling of the onboard hydrogen storage tank of a fuel cell-powered lift truck while it was completely depowered. The in-tank shutoff solenoid valve had recently been replaced, and this was the initial refueling event after the replacement. The fuel zone access panel was removed to allow constant visual leak checking with Snoop leak-detection fluid. The event occurred during the final pressure testing of the repaired system when an O-ring failed at approximately 4500 psi, releasing the entire contents of the hydrogen tank in about 10 minutes. The dispenser hose/nozzle was immediately disconnected, and the leak location was quickly isolated to the tank/valve interface. A 30-foot boundary around the lift truck was cleared of personnel and view more

The contractor was replacing a needle valve and a check valve on the nitrogen purge line to the dispenser because of a small leak at the connection between the needle valve and the check valve. On reinstalling the valves, the contractor installed the check valve backwards, causing the pressure disk in the regulator to fail, venting about 1000 psig hydrogen into the air for about 10 seconds. This was found during testing of the contractor's work before the system was returned to normal service.