While not required, Safety Instrumented Systems with a specific SIL rating are often used on hydrogen systems. The hazard analysis provides guidance as to whether a SIL rating for a given exposure is required and at what level. The SIL level depends on the probability and consequence of occurrence of a given hazard. Hydrogen equipment may be provided with different SIL levels within the same overall system.

Rupture panels can add an additional layer of overpressure protection against internal overpressure. Given the propensity of hydrogen to generate higher over-pressures when ignited compared to other fuels, rupture panels are often part of the safety design for containerized systems. The need for a rupture panel for a specific system will be determined by the system hazard analysis and the applicable codes. Documents such as NFPA 68 and 69 provide guidance on how best to provide explosion prevention and protection.

The containerized electrolysis unit should be installed per manufacturer instructions, the requirements
of its listing such as to ISO 22734, Hydrogen generators using water electrolysis - Industrial, commercial,
and residential applications, and NFPA 2, Hydrogen Technologies Code. A primary consideration for
indoor installation is the potential for hydrogen releases from the system, both planned and unplanned.
Another consideration is the total quantity of hydrogen that could be released within the container or
indoor area, especially with respect to the available ventilation.

The suspected cause was a mixture of oxygen and hydrogen that passed downstream from the electrolysis unit into several storage vessels. Hydrogen-oxygen mixtures are very hazardous. Subsequent ignition resulted in internal pressure that exceeded the limits of the storage system. The design of electrolyzers, detection of upset conditions, and preventing the accumulation of oxygen within the hydrogen system is important for safe operation.

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.

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 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 used to reduce or eliminate unintended vent stack fires is to dilute the flow below the flammable range. This can be a potential mitigation for small releases, but often becomes impractical with larger releases due to the amount of diluent needed.

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 carefully assessed when
they are installed on vent lines.

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 eliminate all such fires so proper design of the vent stack to be able to withstand over-pressures and continuous flame are critical to the design.

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.