Hydrogen
261
to minimize industrial risks and to harmonize the safety culture also in the
field of transportation. A large body of literature, related to hydrogen safety,
is now available, as well as many sites on the internet that contain hydrogen
safety information. The starting point of a safety assessment is the knowledge of the hydrogen hazard. The preliminary hazard lists posed by the
properties of gaseous hydrogen are as follows (www.inl.gov/hydrogenfuels/
projects/docs/h2safetyreport.pdf):
1. Physical properties
• Lighter than air, odorless and colorless gas
• Low viscosity (leaks easily)
• Highly diffusive
2. Pressure
• High-pressure storage can result in pressure rupture, flying
debris
• High-pressure gas jet impingement on body can cut bare skin
• Oxygen displacement in confined spaces
3. Chemical
• Flammable, with nonluminous flame, no toxic combustion
products
• Explosive, 4–74% by volume can deflagrate (typically only a modest over pressure, ~a few psi in open areas) can also detonate
(high over pressure shock wave, ~several atmospheres)
• Low ignition energy, 0.02–1 mJ spark to ignite a deflagration
• Modest autoignition temperature, 574ºC
4. Temperature
• Could be stored at room temperature
5. Materials issues
• Embrittlement of metal and plastics
6. Toxicological
• Asphyxiation in confined spaces
• No other toxic concern effects
The hazards related with liquid hydrogen because of its properties are given
below.
1. Physical properties
• Odorless, colorless, cannot easily be odorized since odorants will
freeze out at cryogenic temperatures
• Boiloff gas quickly warms and then is lighter than air
261
to minimize industrial risks and to harmonize the safety culture also in the
field of transportation. A large body of literature, related to hydrogen safety,
is now available, as well as many sites on the internet that contain hydrogen
safety information. The starting point of a safety assessment is the knowledge of the hydrogen hazard. The preliminary hazard lists posed by the
properties of gaseous hydrogen are as follows (www.inl.gov/hydrogenfuels/
projects/docs/h2safetyreport.pdf):
1. Physical properties
• Lighter than air, odorless and colorless gas
• Low viscosity (leaks easily)
• Highly diffusive
2. Pressure
• High-pressure storage can result in pressure rupture, flying
debris
• High-pressure gas jet impingement on body can cut bare skin
• Oxygen displacement in confined spaces
3. Chemical
• Flammable, with nonluminous flame, no toxic combustion
products
• Explosive, 4–74% by volume can deflagrate (typically only a modest over pressure, ~a few psi in open areas) can also detonate
(high over pressure shock wave, ~several atmospheres)
• Low ignition energy, 0.02–1 mJ spark to ignite a deflagration
• Modest autoignition temperature, 574ºC
4. Temperature
• Could be stored at room temperature
5. Materials issues
• Embrittlement of metal and plastics
6. Toxicological
• Asphyxiation in confined spaces
• No other toxic concern effects
The hazards related with liquid hydrogen because of its properties are given
below.
1. Physical properties
• Odorless, colorless, cannot easily be odorized since odorants will
freeze out at cryogenic temperatures
• Boiloff gas quickly warms and then is lighter than air