Hydrogen concentrations begin to be explosive at around 14% in air, and concentrations in excess of about 59% in air are typically not explosive. This range is encompassed within the flammable range.
- If liquid hydrogen is warmed and vaporizes into a gaseous state, it occupies 848 times more space, so a confining vessel or pipeline could easily become over-pressurized.
- Pressure-relief devices (PRDs) such as rupture disks or relief valves should be installed to prevent over-pressurization from occurring. The PRD should be vented to a safe location.
Causes of explosions:
- Mechanical failure of a vessel containing a high-pressure fluid
- Rapid chemical reaction producing a large volume of hot gas