ASTM might be the best point of contact for crafting this test. The ASTM F38 Committee on Unmanned Aircraft Systems is probably the best source of information on drone airworthiness criteria. They have a subcommittee developing a standard on fuel cell drone safety. One Panel member has been involved in a test with an LD vehicle tank filled with hydrogen that was dropped 60m onto a concrete pad…

This is an interesting question because of the special considerations associated with the H2-air mixture flashback scenario during turbine startup and shutdown. In-line deflagration arresters and detonation arresters for H2-air mixtures are different than those for most other fuels and need to be certified for use with hydrogen. They are commercially available, and NFPA 69 has a good chapter…

The HSP discourages the use of this type of piping for hydrogen despite the low likelihood of ignition within the pipe itself. The polyethylene film can indeed develop a charge and, depending on the film thickness and substrate wall material, will eventually produce an electrostatic discharge. Since the nominal hydrogen concentration is so high (and assuming the purge-in and purge-out…

Precautions applicable to oxy-acetylene torches are likely applicable here and are a good starting point. Recommendations for the hardware are best provided by the cylinder supplier, and all these parts can be purchased from their respective catalog. All three devices in the question should have UL listings, FM approvals, or some other nationally recognized testing laboratory (NRTL) listing,…

The information provided is not only outdated in terminology, but also misleading in quantifying the dispersion of hydrogen in terms of comparison of diffusion of air in air. Hydrogen diffuses 4X faster than air, and the rate of mixing has many variables, so there isn’t just one answer. However, it’s generically safe to say that an initial hydrogen gas cloud outdoors and unconfined will…

There is no generalized exception for hydrogen fueling stations.  However, PSM is intended for employee protection. It’s not intended for retail operations or customers. Through paragraph 1910.119 (a)(2)(1) of the regulation, PSM exempts retail facilities. Some may use this exemption as a means to exclude H2 retail fuel sites from PSM.

Fuel stations that are non-retail, such as…

The cleanliness of an H2 piping system is often based on end use requirements since the purity of the system may impact the end use application. Cleanliness required for end use purity is usually much greater than that required to prevent condensation or oxygen content sufficient to create a safety risk. While not required for the same safety reasons as oxygen safety, specifying a system to be…

Yes, the pressure safety relief system on LH2 tanks is sized for the loss of vacuum condition. The spring-loaded safety valves are sized for lower demand cases such as runaway pressure build or loss of vacuum. Higher demand requirements, such as loss of vacuum combined with fire, are handled by the rupture discs and are sized for such an event.

Off gassing of hydrogen from battery sources depends on battery chemistry, usage/duty cycle, age, and other considerations. The specific battery manufacturer should provide recommendations for fire prevention and mitigation in battery charging rooms as the battery itself impacts how an event would be mitigated. Adequate ventilation such that combustible mixtures cannot develop is a general…

Because hydrogen is labeled as a hazardous substance, sometimes people are concerned about the environmental impact of releasing liquid hydrogen. There are currently no regulations that require reporting of hydrogen releases for environmental reasons.

However, there are safety implications. For example, the US DOT requires reporting of hazardous materials releases under certain…