Cryogenic hydrogen, handling

The potential hazard associated with expansion of liquid to gas is substantial for hydrogen, as it is for other cryogenic fluids. Careful attention must be given to the location of relief devices in liquid hydrogen handling systems. 

As with other cryogenic liquids, cryogenic hydrogen is not to be used or handled by any personnel unless they are familiar with its properties and skilled in the procedures necessary for its safe use. Cryogenic liquids other than oxygen which vaporize in enclosed areas may reduce the oxygen content in the atmosphere below the level necessary... 

NASA is also considering a more advanced aircraft such as Mach 5 to cut Pacific travel time to about three hours, but in this case kerosene fuel is no longer acceptable, and Hquefted natural gas or Hquefted hydrogen would be needed to provide the necessary cooling and stabiUty. However, a completely new fueling system would be required at every international airport to handle these cryogenic fluids. 

The technologies for routine handling of large quantities of hydrogen have been developed in the chemical industry. Hydrogen can be liquefied at low temperature (-253°C) and delivered by cryogenic tank truck or compressed to high pressure and delivered by truck or gas pipelines. 

Cryogenic fuels like liquid hydrogen are more difficult to handle and substantially more difficult to store compared to hydrocarbon fuels like gasoline or aviation kerosene. Even with highly-insulated double-walled, vacuum-jacketed storage tanks liquid hydrogen can evaporate at a rate of almost 9% per day. 

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