CHARACTERISTICS OF OXYGEN

Characteristics of Oxygen

Oxygen is one of the most abundant elements on the earth. As an uncombined gas it makes up more than one-fifth of the air we breathe. Nearly 90% of the weight of water is oxygen, and oxygen is found in most of the soil and rock that makes up the earth's crust.

As a gas, oxygen is colourless, odourless and taste­less, and it is extremely active chemically and will combine with almost all other elements and with many compounds. When any fuel burns, it unites with oxygen to produce heat, and in the human body, our tissues are continually being oxidized which causes the heat our bodies produce. This is the reason an ample supply of oxygen must be available at all times to support our life.

Oxygen is produced commercially by liquefying air, and when the nitrogen is allowed to boil off, relatively pure oxygen is left. Gaseous oxygen may also be produced by the electrolysis of water. When electrical current is passed through water (H₂O), it will break down into its two elements, hydrogen and oxygen.

Oxygen will not burn, but it does support com­bustion so well that special care must be taken when handling it that it is not used where there is any fire, hot material or any petroleum products. If pure oxygen is allowed to come in contact with oil, grease or any such product, it will combine violently and generate enough heat to ignite the material, and it will burn with a very hot flame.

Iron and steel may be cut by heating it red hot with an oxyacetylene flame and then directing a jet of pure oxygen onto the hot metal. The oxygen will combine with the hot metal and produce a flame hot enough to burn through it, cutting it as though with a knife.

Commercial oxygen is used in great quantities for welding and cutting and for medical use in hospitals and ambulances. Aviators breathing oxygen is similar to that used for commercial purposes, except that it is additionally processed to remove almost all of the water that could freeze and stop the flow of oxygen when it is so vitally needed. Because of the additional purity required, you must never service an aircraft oxygen system with any oxygen that does not meet the specifica­tions for aviators breathing oxygen. This is usually military specification MIL-O-21749 or MIL-0­27210. These specifications require the oxygen to have no more than two millilitres of water per litre of gas.