The answer will depend on if it is only H2 measured or if VOCs are also included. The type of gas sensor may change since many detectors are limited to flammable gases. To provide feedback, the Panel would require more details on the sensors being used on the project and the failure modes. There are concerns about allowing hydrogen concentrations as large as 3.5% for the high level alarm.…

There are many manufacturers of multiple  types of flame detectors and it’s best to seek their input for the advantages of different types for specific applications. Regarding flame detector technology, UV detectors have been prone to false alarms from outside sources such as sunlight, lightning, and welding/cutting torches. The newer triple-IR detectors that are specifically designed and…

One pertinent reference is a Sandia National Laboratories paper by Schefer et al: Spatial and radiative properties of an open-flame hydrogen plume, Intl J. Hydrogen Energy, 31 (2006): 1332-1340. Information on this and other similar papers are available at https://h2tools.org/bibliography. Further information can probably be obtained from the author of this paper and other papers reporting…

The Panel is not aware of any standard for hydrogen detectors for onboard vehicle applications. Some information is available in the SAE Technical Information Report: TIR J3089 Characterization of On-Board Vehicular Hydrogen Sensors, which was published in 2018.

The UN ECE R134 regulation is a good requirement to follow as it copies the language in the UN GTR #13 regulation. The updated version of this UN document (UN GTR #13 Phase 2) is currently in approval review at the GRSP in Geneva and should be approved by the end of 2023. Nevertheless, since the US Department of Transportation’s National Highway Traffic Safety Administration is a contracting…

NFPA 2 provides Tables in Chapters 7 and 8 that specify the hazardous area classifications surrounding vent stack outlets. These are based on typical vent systems and flows, but are only applicable for smaller systems. The designer of a vent system should apply the principles of documents such as IEC 60079-10-1 (also required by NFPA 2) or NFPA 497 to evaluate larger vent releases where the…

Guidance for location of vent stacks is provided by NFPA 2, Hydrogen Technologies Code, which also references CGA G5.5, Hydrogen Vent Systems, for additional guidance. Minimum distances to vent stack outlets should be determined from dispersion and radiation analyses. The height of the vent stack and orientation of the release will affect the minimum separation distance.

Dispersion and radiation analysis should be conducted to ensure that the hydrogen cloud will not interfere with the flight path of aircraft. In addition, there may be maximum height requirements due to airport requirements depending on the location of the stack.

The manufacturer’s calibration requirements should be followed to ensure proper operation of the
detection system. The requirements will vary depending on the type of detector and the environment in
which they are installed. Calibration can usually be performed by the user/owner if properly trained and
supplied with calibration gas, etc.

Training personnel and equipping them with portable gas detectors to properly identify the gas that is
leaking can play an important role in both troubleshooting and emergency response.