Each cryogenic liquid storage vessel (both stationary and mobile) should be legibly marked to indicate:
"LIQUEFIED HYDROGEN - FLAMMABLE GAS".
Documentation for each vessel should include a description of the vessel, a list of available drawings or other documents, the most recent inspection results, and the responsible person's name. Vessels should also be marked per the appropriate code (i.e., ASME, NFPA, or DOT).
A sign should be placed on the vessel near the pressure-relief valve vent stack saying "Do not spray water on or in the vent opening".