Electrolyzers should be installed per manufacturer recommendations and meet the criteria of their
listing, such as ISO 22734, Hydrogen generators using water electrolysis - Industrial, commercial, and
residential applications. There are several methods such as partitions, enclosures, ventilation, and
purging that can be used to address non-classified electrical equipment.

There are dozens of safety considerations for safe design of hydrogen vent stacks. Their primary function
is to vent the hydrogen safely, so vent stacks should be designed such that the gas dispersion and
radiation profile (if ignited) do not impact surrounding equipment, buildings, or people. Documents such
as CGA G5.5, Hydrogen Vent Systems, provide numerous details regarding design…

As with any high pressure gas, hydrogen vents can be very loud. Consideration must be given to the
surrounding population and special provisions can be taken to reduce the noise level of releases if
needed. When installed, care must be taken that the sound quieting system can withstand the
flow/pressure of the release and does not impede the required flow.

Each system must be evaluated individually, and it depends on the amount and location of possible
releases. Routing vent lines to a vent stack is the most common approach when venting directly to
atmosphere is not acceptable.

Vent stacks should always be grounded in accordance with electrical standards which will reduce the probability of, but not eliminate, vent stack fires. There are numerous design features, such as toroidal rings, that have been suggested to reduce vent stack fires. However, given the many sources of ignition that can potentially ignite vent stack releases, it is virtually impossible to…

The suitability of flame arrestors depends on the design of the system, but generally flame arrestors are
rarely needed for hydrogen systems when there is a 100% hydrogen atmosphere upstream of the vent,
and when the downstream vent system is designed to withstand internal ignition. Flame arrestors can
also cause potential blockage or restriction of flow, so relative risks need to be…

There is some indication that toroidal rings can reduce static buildup and ignition of hydrogen from a vent. However, while toroidal rings may help with static, they have not been proven to eliminate all static ignition sources. There are also other sources of ignition that they would not prevent, so they might reduce but not eliminate, vent stack fires. Another method that can be reliably…

The routing will be dependent on the system design, size of release, and evaluation of the hazards.
Smaller systems are rarely vented to a flare due to complexity, availability and permitting considerations.
Facilities handling large amounts of hydrogen such as production plants will often have a flare system
since they have more capability for this additional onsite infrastructure.…

There is no maximum flow-rate that can be vented to the atmosphere, but the hazard analysis should consider the potential risk of dispersion, radiation, and overpressure as part of the vent system design. Flare systems are often used at large hydrogen production facilities as one means to prevent a large unignited cloud from forming but will depend on the specific application.

Leakage/loss depends on the vessel design. Metallic or metallic lined vessels have extremely low permeability and losses through the vessel walls are typically imperceptible. Conversely, Type IV composite vessels which have non-metallic liners are subject to permeation. They are required to meet maximum permeation rates as part of their certification. Fugitive emissions from piping systems can…