A metal hydride storage system was refilled using compressed hydrogen in a closed lab environment. The tank system is an in-house development and is optimized for high hydrogen storage density and use with an air-cooled fuel cell. The system is equipped with a pressure relief valve that opens gradually at 35 bar to protect the tank from overpressure conditions. The tank itself is designed to adsorb 400 g of hydrogen at a pressure less than 15 bar.

For refueling, the secondary pressure on the compressed hydrogen supply container was set to 20 bar and the adsorption of the hydride was started without hydrogen flow limitation. Due to the exothermic nature of the hydride upon recharge, as expected a sharp increase in tank temperature was measured. The tank was uncooled because the view more

An instrument engineer at a hydrogen production facility was arresting the hydrogen leakage in tapping a pressure transmitter containing 131-bar hydrogen gas. The isolation valve was closed and the fittings near the pressure transmitter were loosened. The pressure dropped from 131 bar to 51 bar. The fitting was further loosened (though very little); the instrument tube slipped out of the ferrule and got pulled out of the fitting. With the sudden release of the 51-bar hydrogen, there was a loud pop (like a fire cracker) and the spark-proof tool was observed to have black spot on it. The volume of the hydrogen gas released was small, since it was in the tapping line only.

During a facility walk-through, it was noted that a combustible gas (hydrogen) monitoring system installed in a furnace room was inoperable (the system had been unplugged). This system is used to detect and warn facility employees of an explosive or flammable environment. An explosive or flammable environment can only occur if there is a leak in the system, which would not be expected to occur during normal operations. When the system was reactivated, no leaks were indicated.

The incident had the following three causes:

A procedure describing administrative controls necessary to ensure safe operations in the area should have been developed and implemented prior to disabling the hydrogen monitoring system.
The hydrogen monitor was not hard-wired, which allowed it view more