A partial pressure sensor for an automated gas environment system (AGES) was not functioning correctly for pure hydrogen flow. While personnel were troubleshooting the problem, a burst disk ruptured resulting in a leak of hydrogen gas and actuation of a flammable gas alarm.

System troubleshooting involved the installation of a small hydrogen gas cylinder and temporary manual valve in an engineered ventilated enclosure adjacent to an instrument sample well. A burst disk associated with the temporary manual valve ruptured upon opening of the gas cylinder valve. The vented gas, exhausting through an engineered exhaust system, triggered the flammable gas detector. Personnel promptly evacuated the area in accordance with established procedures. Appropriate personnel responded to the view more

Hydrogen alarms went off in a research laboratory and the fire department was called, but no hydrogen leak was detected. The hydrogen system was leak-checked with helium and found to be leak-free except for a very small leak in the manifold area. The manifold leak was fixed, but because of its small size, it was not thought to be the likely source for the hydrogen alarm trigger. While hydrogen was removed from the system for leak-testing, the hydrogen alarm went off again, and again the fire department responded. There was no hydrogen present in the system to trigger this alarm. Other sources within the building were checked to see what may have set off the alarm, but none were found. One research area uses small amounts of hydrogen, but laboratory logs indicate that none was being 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