People who work with gaseous hydrogen should understand its basic characteristics, including:

• propensity to leak
• buoyancy
• diffusion in air

Hydrogen is the most buoyant gas for a given temperature and pressure. With a specific gravity of 0.07 compared to air, it will rise quickly under atmospheric conditions. Also, hydrogen will diffuse rapidly in air, about four times faster than natural gas.

All pressure vessels, pressurized components, and pressurized systems should be designed, fabricated, installed, operated, periodically inspected, maintained, repaired, and certified in accordance with applicable codes and standards.