Hazards of Chemicals and Gases
DOE-HDBK-1015/2-93
COMPRESSED GASES
Rev. 0
CH-05
Page 29
Compressed Gases Summary (Cont.)
The physical properties and special precautions for hydrogen include the following:
It is the lightest of all elements
It cannot be detected by any of the senses
It has a flammable range of from 4.1 percent to 74.2 percent by volume in air
It burns with an almost invisible flame
Hydrogen is classified as an asphyxiant, and special precautions, such as adequate
ventilation and the elimination of possible sources of ignition, should be taken to
prevent hydrogen accumulation.
The physical properties and special precautions for nitrogen include the following:
It makes up more than 78 percent of the earth's atmosphere
It will not burn or support combustion
It cannot be detected by any of the senses
It is used to inert systems that contain, or have contained, flammable liquids or
gases
It is fairly soluble in the blood and if the dissolved nitrogen escapes from the
blood in the form of small bubbles in the bloodstream, intense pain occurs and
effects are often fatal
Nitrogen is an asphyxiant and it could cause a serious oxygen deficiency. Special
precautions, such as adequate ventilation, should be taken to prevent nitrogen
accumulation.
The physical properties and special precautions for oxygen include the following:
It supports combustion, but does not burn
Ignition temperature of a combustible material is lower in enriched oxygen
It readily combines with other elements and compounds, with spontaneous
ignition in some cases
When oxygen comes in contact with oil, grease, or fuel oils, it may ignite violently.
Every possible precaution must be taken to prevent this combination. If pure
oxygen were inhaled continuously for extended periods the reactions in the body
would be too rapid and cause harmful effects. Finally, oxygen valves should be
operated slowly. Abruptly starting and stopping oxygen flow may ignite
contaminants in the system.
