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

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.

While hydrogen gas detectors are less effective outdoors, they can be an important safeguard as part of an overall hydrogen system design. They have been used in many cases to automatically shut down equipment and isolate hydrogen supply. Location and type of detectors depend on the system design and siting, but when installed, should be in areas that are most likely to be exposed to hydrogen…

Training personnel and equipping them with portable gas detectors to properly identify the gas that is
leaking can play an important role in both troubleshooting and emergency response.

The manufacturer’s calibration requirements should be followed to ensure proper operation of the
detection system. The requirements will vary depending on the type of detector and the environment in
which they are installed. Calibration can usually be performed by the user/owner if properly trained and
supplied with calibration gas, etc.

Many methods are used to mitigate the risk of a tube trailer hose loss of containment incident. Examples that otherwise exceed code requirements are provided below. These have been deployed in various combinations depending on the risk analysis for a particular system: 

1. Installation of automatic shutoff valves on the tube trailer upstream of the hose to activate upon hose…

A "drop and swap" delivery system using tube trailers is a common and accepted method of supply for both industrial and fueling station applications. While NFPA 2 - 2023, paragraph 10.6.3.5 states, "The use of hose in a hydrogen dispensing system shall be limited to vehicle fueling hose," this is intended for the dispenser itself, not the entire fueling station. This does not limit the use of…

Gaseous hydrogen can be stored forever as long as the system integrity is maintained. However, liquid hydrogen is “use it or lose it” and will boil from system heat leak and build pressure unless it is used or vented. This is not usually an issue for continuous use or low-pressure applications which can use hydrogen gas pressure directly from the tank.  

For intermittent or high…

The Panel is not aware of any standard for hydrogen detectors for onboard vehicle applications. Some information is available in the SAE Technical Information Report: TIR J3089 Characterization of On-Board Vehicular Hydrogen Sensors, which was published in 2018.