Hydrogen Facts
Hydrogen is undetectable by human senses (i.e. colorless, odorless, tasteless).
Hydrogen burns colorless and a fire would be undetectable in the visible light spectrum.
Because of hydrogen’s small molecular size it can easily pass through porous materials. Common storage materials are 300 series stainless steel, copper, and brass.
It is a non-toxic, but the primary health hazard from being exposed to hydrogen gas is asphyxiation because the human body will accept hydrogen in place of oxygen from the air.
Rapid expansion of compressed hydrogen will cause self ignition.
Hydrogen has a low ignition energy of 0.02 millijoules (mJ) which is approximately one tenth that of gasoline.
Hydrogen gas disperses quickly, rising at a rate of 20 m/s or 45 mph, diluting quickly to below a 4% mixture with air, and flames emit low levels of heat.
Below is a table that compare several aspects of hydrogen, gasoline vapor, and natural gas.
| Hydrogen | Gasoline Vapor | Natural Gas | |
| Flammability Limits (in air) | 4% to 74% | 1.4% to 7.6% | 5.3% to 15% |
| Explosion Limits (in air) | 18.3% to 59% | 1.1% to 3.3% | 5.7% to 14% |
| Ignition Energy (mJ) | 0.02 | 0.20 | 0.29 |
| Flame Temp. in air (°C) | 2045 | 2197 | 1875 |
Stoichiometric Mixture (most easily ignited in air) |
29% | 2% | 9% |
