An alarm sounded at a recently inaugurated hydrogen fueling station in a major metropolitan area. One out of a total of 120 high-pressure hydrogen cylinders, located on the roof of the fueling station, failed in service. Gaseous hydrogen was leaking from a screw fitting of the cylinder, but the hydrogen was not ignited. Three hydrogen gas sensors detected the leakage and triggered an alarm that resulted in an immediate emergency shutdown, isolating the leaking high-pressure cylinder bank from the other three banks and notifying the local fire department. No personnel were allowed to enter the roof area, approximately 7-9 meters above ground level.

The police isolated the area around the fueling station within a radius of 200 meters. The maximum content of the leaking cylinder view more

A single-stage regulator "failed" while flowing hydrogen gas from a standard 200 cu.ft. gas bottle. The regulator had functioned properly prior to the event through several on-off cycles. During the event, a solenoid valve was opened to allow hydrogen to flow, when a rather loud noise was noted and gas began flowing out of the pressure relief valve on the side of the regulator. It was noted that the low-pressure gauge on the regulator was "pegged" at the high side (>200 psi). The valve on the bottle was shut off, and hydrogen flow was immediately stopped. Hydrogen flowing out of the relief valve did not ignite. With the bottle shut off, the regulator was removed and replaced with another regulator of the same type, and activities continued.

The failed view more

A pressure relief device (frangible burst disk) on one of a hydrogen delivery tube trailer's 26 tubes failed prematurely and released hydrogen while filling a hydrogen storage tank at a government facility (see Attachment 1). Prior to the filling process, all procedures and safety checks, including connection to the facility's regulator/distribution control system with leak checking and follow-up verification of leak checking by facility personnel, were completed (see Attachment 2 for more details). During the filling process, a person walking near the facility heard the noise of escaping gas that included occasional popping sounds typical of bursts of gas release. Facility personnel were alerted and the tube trailer vendor's incident response team was dispatched to the view more

A hydrogen alarm sounded when hydrogen buildup occurred in an unmanned switching room containing backup lead acid batteries after the exhaust ventilation fans failed to start at the 1% hydrogen trigger level. Failure of the ventilation fans to vent the normal off-gassing hydrogen from the lead acid batteries resulted in the hydrogen concentration in the room increasing to 2%, which triggered the hydrogen alarm. The alarm was automatically sent to an alarm-monitoring company that alerted the local fire department as well as company personnel of the condition. The fire department was dispatched to the scene and, along with company personnel, provided secondary ventilation to lower the hydrogen concentration to normal conditions. Hydrogen leakage from lead acid batteries is normal, and view more

The malfunctioning of the non-return valve of the hydrogen compressor caused the pressure between the hydrogen bottle and the compressor to rise up to the maximum allowed pressure of 275 barg. As a consequence, as foreseen by the safety system, the rupture disk of the safety valve broke and the hydrogen content of the gas bottle and the pipe section involved was released on top of the building. The flame was seen for a very short period by a guard, and could have been caused by the following series of events:

Expansion of hydrogen at the end of the exhaust pipe.
Consequent mixing of hydrogen and air up to a near-stoichiometric mixture and increase of gas temperature.
Mixture ignition due to sparks from static electricity generated by gas molecule friction against view more

A vehicle fill was initiated by the operator. During the hose pressurization step, a leak was observed at the breakaway fitting. The operator pressed the emergency stop to terminate the fill.

A vehicle fill depleted the high-pressure hydrogen inventory. The compressor turned on to refill the storage by compressing 60 psig gas from a liquid hydrogen tank up to the 5500 psig storage pressure. After running about 2 hours, a crankshaft bearing started to fail. This allowed greater movement of the shaft, which led to a shaft seal leaking hydrogen. The compressor shut down on low suction pressure and then the system was shut down using the e-stop by the emergency responders.

A small research sample of approximately 5 grams of aluminum hydride (alane) doped with 2-3 mol % TiCl3 contained within a glass ampoule ruptured after transit while stored in an office cabinet. The rupture was attributed to over-pressurization caused by hydrogen gas buildup within the sample over a four-month period. The glass ampoule, contained within a 0.2-inch thick cardboard shipping tube, was not a pressure-rated container. The rupture resulted in glass chards penetrating the protective cardboard shipping tube. The aluminum hydride, a fine powder, was released from the shipping tube during the pressure release. The fine aluminum powder leaked from the cabinet and set off a local smoke alarm that brought emergency responders to the scene. No personnel were present in the area when view more

The System Shutdown logic activated and the compressor automatically shut down on high vibration. When the operator investigated the unplanned shutdown, two broken compressor head fasteners were noted lying on the deck.

Two fitting failures were experienced for fueling equipment filling systems. Both fittings were installed in the system thermal chamber experiencing ambient temperatures of -40C to +50C. They were connected in high-pressure lines used for 70MPa hydrogen fueling.

The first fitting, a 0.25-inch NPT hose connection, was in service for approximately one year with no signs of leakage. The failure was noticed when the system was pressurized during a filling sequence. The failure was discovered by an audible hissing noise during leak checking. The system was depressurized and the fitting removed and replaced. The system was re-pressurized with no further leakage.

When attempting to reconnect a second fitting, a double-ferrule high-pressure connection, the fitting in question view more