Purging of vent systems is not required and in most instances is not recommended.
A nitrogen purge is generally not needed for a vent system designed in accordance with CGA G-5.5. However, there are times where this might be considered or required due to the specific design of a system. Where determined by a risk review to be needed, A continuous purge into a vent system…
Even if a small experiment is being run inside a fume hood, the best practice is to use a dedicated vent line for hydrogen which vents hydrogen to a safe location outside. This is especially recommended for planned venting. This practice avoids situations where flammable mixtures could develop. Each system is unique and should be evaluated and approved for use independently…
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…
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.
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…
Such a compressor should NOT be used for hydrogen. There are many issues with converting a compressor to hydrogen service. First and most important, this must be approved by the manufacturer. Examples of concerns for a non-hydrogen compressor used for hydrogen service include (but are not limited to):
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 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…
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 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…
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