Vaporization of a trapped volume of LH2 will lead to significant increase in pressure due to the very large expansion ratio as the liquid converts to gas. Relief devices are required since the pressure increase is likely to be far in excess of the pressure rating of the system. When vaporized as part of a flowing process, pressure will not increase. As the LH2 is warmed, it undergoes a phase…

A pressure of 600 kPa (87 psi) is relatively moderate, so the combustion properties are similar to those at atmospheric pressure where the autoignition temperature of hydrogen is 585°C. 

H2-air flammability limits vary with temperature  . The H2-air lower flammability limit is virtually the same as the H2-O2 lower limit. However, the H2-O2 upper flammability limit increases substantially to about 95% at room temperature and gets even higher at elevated temperatures.

Liquid hydrogen is much less likely to pool than liquified natural gas (LNG) due to its low heat of vaporization. Very large facilities are often equipped with methods to enhance vaporization, such as crushed stone under tanks, as well as diversion systems to allow liquid hydrogen to spill and boil off in a safe area. Care needs to be taken that diversion systems do not create a hazardous…

By definition, liquid hydrogen can BLEVE, but this is highly unlikely. Liquid hydrogen is stored in a double wall tank with vacuum insulation. This protects the primary pressure vessel from direct impingement and the very cold liquid provides self-cooling of the vessel walls. Tanks are also equipped with redundant pressure relief systems that are sized for fire exposure.

Underground storage tanks can be either installed in a vault or directly buried. Both offer additional
protection from external impact and fire, but each has unique challenges. Vaults must be properly
ventilated and designed to not create an explosion or asphyxiation risk. Direct burial vessels should not
have any underground leak points and must be protected from corrosion. Both…

Most common odorants will contaminate fuel cells. Additionally, hydrogen's small molecule and high buoyancy make it challenging to find a compatible odorant. Research is being conducted on fuel cell compatible odorants, but there are none currently in use. Like liquefied natural gas, liquid hydrogen also can’t be odorized due to its cryogenic temperature.

Composite cylinders can be manufactured to standards written by CSA, ASME, and ISO depending on the application and local requirements. Several ISO standards can serve as the basis for composite cylinder approvals within North America.

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…

Store flammable gas cylinders such as hydrogen, separated from oxidizing (e.g. oxygen), toxic, pyrophoric, corrosive, and reactive Class 2, 3, or 4 gases. Non-reactive gases, such as helium, may be co-located. See codes and standards such as NFPA 2 [7.2.1.1 Incompatible Materials] for further guidance.