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.

Flare-less compression style fittings are commonly used. Choose tubing materials and tube wall thicknesses suitable for hydrogen and pressures you are using. Make sure all tubing joints are properly made, mechanically supported to minimize stress and vibration, are in a ventilated space, and are easily accessible for inspection and leak testing. 

In general, indoor storage should be limited and the use of hydrogen indoors should be the least necessary. Look to store flammable gases outdoors in dedicated protected area when practicable. Check to see what adopted building and fire codes in your jurisdiction say. NFPA 2, Hydrogen Technology Code, Sections 6.4.1 and 16.3 prescribe requirements to limit hydrogen storage and use in…

Purging is not recommended as a continuous part of vent stack operation. However, maintenance activity is a transient event and it’s prudent and recommended to purge a vent system prior to performing maintenance. It’s always possible that hydrogen could be leaking internally from a valve or other component and therefore create a hazard. Of particular note, care must be taken that proper…

We are not aware of a study for blended NG/H2. However, for high concentrations of NG, the vent system should be similar to NG, which still recommends a vent system as NG is less dense than air. For nearly pure hydrogen the recommendations of this presentation are in effect.