AICHE ELA253 CHS ” Introduction to Hydrogen Safety for First Responders” is a good reference and discusses both LH2 and GH2. LH2 fires are very unusual. LH2 releases usually are GH2 so the fires at either ambient for low flow or the GH2 is a cryo temperature for high flow. Fires from LH2 tanks ignite less frequently than GH2 high-velocity releases. The colder the gas the less potential for…
CGA G-5.5 states: All vent stacks shall be grounded and meet the requirements of NFPA 70, National Electrical Code, for integrity and system design and also references NFPA 77, Recommended Practice on Static Electricity, and NFPA 780, Standard for the Installation of Lightning Protection Systems.
For lightening refer to NFPA 780 and for grounding of the Hydrogen equipment, refer to…
1. As of January 2024, we are not aware of any public data on incidents or investigations where a hydrogen fired steam boiler exploded.
2. The potential for detonations within a boiler tube would depend on both the equivalence ratio of the hydrogen present and the diameter of the boiler tube.
a. At a minimum, if the circumference of the tube is…
Yes, these would be ignitable mixtures. In this case, it does not appear complicated geometry is involved, so 1200 psig pipe should be more than adequate to protect against internal deflagration. The most likely scenario is a "backfire," similar to a car, where ignition occurs too soon and shoots out the open end of the pipe. Consider using an inline deflagration flash arrestor on the…
Flammable hydrogen releases can result in deflagration and transition to a detonation. Whether the
deflagration transitions to a detonation depends on numerous parameters such as cloud size, hydrogen
concentration, confinement, and congestion. Releases into confined or congested areas are more
susceptible to generating significant deflagration over-pressures and more likely to…
There are numerous models that can be used to assess the consequence and risk of leaks and releases.
One such model is HYRAM which is publicly available from Sandia and the US DOE.
Emergency response procedures must be developed for each system based on its design. The
procedures generally include steps to clear personnel from the immediate area, isolate the hydrogen,
shut down the equipment, contact local responders, and protect surrounding equipment/structures until
the hazard is mitigated or the incident is over.
There are two parts for such a system to be effective. First, the system would have to activate quickly enough to establish a water mist throughout the region of interest (i.e., region occupied by a flammable gas mixture) before it could be ignited. This is challenging in terms of timing, and the impact of spraying water inside an enclosure filled with equipment not designed to get wet can be…
Explosion testing with hydrogen should be utilized only where there is not an established alternative and then only by personnel experienced in such testing.
Testing with hydrogen is always a challenge and needs to be approached carefully due to significant differences in properties between hydrogen and propane. Hydrogen can develop significantly higher overpressures and preliminary…
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