Leak detection system requirements depend on the system design and applicable codes. The
appropriateness of detection equipment depend on many factors, including the type of system,
application, location, and probability of leaks. For example, hydrogen refueling stations are required by
code to be equipped with leak detection systems.

Speed of detection, detection limit, location, and cross-sensitivity are some of many criteria that might be used for selecting a detector. A common setpoint for gaseous hydrogen detection is 25% of LFL, or 1% concentration in air. However, the detection limit also depends on the system and exposure. When specific hazards are likely, detectors may have detection limits in the low-ppm range.…

Nitrogen/helium blends are frequently used to leak test hydrogen systems.

In the U.S., liquid hydrogen fueling stations and dispensing equipment are addressed within NFPA 2, Chapter 11. Dispensing is covered within Section 11.3. When liquefied hydrogen is used as the supply for high pressure gaseous fueling, then Chapter 10 of NFPA 2 would apply.
ISO standards are also being developed for global LH2 fueling protocols.
 

If liquid hydrogen usage is sufficiently high at the fueling station, there may be no need to vent any boiloff generated from the LH2 storage tank. Boil-off gas should be minimized through system design, but where needed, the boil-off hydrogen along with any other hydrogen released must be vented through a local vent stack which is constructed to safely vent the hydrogen in accordance with CGA…