Page 109 - Engineering Rock Mass Classification_ Tunnelling, Foundations and Landslides

TABLE 7.7 Properties of Various Gases That May Be Present in a Tu

Gas Density Color Odor Source
Oxygen (O2) 1.11 None None Air is normally 2

Nitrogen (N2) 0.97 Yellow None Air is normally 7
Carbon dioxide (CO2) 1.50 None None
Air is normally 0
Carbon monoxide (CO) 0.97 None None is produced by d
and fires, and is
exhaust

Present in diese
blast fumes

Methane (CH4) 0.55 None None Present in certai
containing carb

Hydrogen sulfide (H2S) 1.19 None Rotten Present in certai
eggs and sometimes

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