Industrial gas is a group of gases that are commercially manufactured and sold for uses in other applications. The most common industrial gases are:air gases - oxygen (O2), nitrogen (N2) and argon (Ar) rare gases - such as helium (He), krypton (Kr), xenon (Xe) and neon (Ne) and other gases like hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2) and nitrous oxide (N2O) ,chlorine (Cl2), hydrogen chloride (HCl) and sulphur dioxide (SO2) ,acetylene (C2H2), methane (CH4) and propane (C3H8).
Oxygen (O2, gas at Oo/1 matm., 1.429 g./1; critical. temp., 118o.8; crit. pressure, 49.7 atm.) is a colorless, odourless, and tasteless gas, somewhat heavier than air. It is one of the most active elements and plays on essential part in the
respiration of living cells and in combustion. It is by far the most abundant elements; it forms 21% by volume of the atmosphere and eight-ninths by weight of water; it occurs as silicates in the earth's crust. Oxygen occurs usually in the form of diatomic molecules but triatomic ozone is also found.
As for nitrogen, chemical fertilizer makers used it for synthesis of ammonia and production of calcium cyanamide through installation of their own nitrogen separators. In recent years, however, the characteristics of nitrogen as inactive gas have come to be utilized by the petrochemical, textile, electronic and other industries as atmospheric gas.