when supplied for use in oxyacetylene welding and cutting application, oxygen is contained in seamless steel cylinders which have a capacity of 220 cubic feet of oxygen at a pressure of 2,000 pounds per square inch and at a temperature of 70 f .a typical oxygen cylinder is shown in figure
OXYGEN AND ITS PRODUCTION.
a. oxygen is a colorless, tasteless and odorless gas, slightly heavier that air. it is noninflammable (that is, it will not burn of itself ), but it will support combustion with other elements, and this combustion or burning will give of considerable heat and light. in the free state, it is one of the most common elements, the atmosphere is made up of approximately 21part oxygen and 78 parts nitrogen, the remainder being rare gases. rusting of ferrous metals, the discoloration on copper and corrosion of aluminum are all due to the action of atmospheric oxygen on these metals. this action is known as oxidation.
b. the principal use of oxygen in the oxyacetylene welding process is for cutting ferrous metals and for burning acetylene and other fuel gases in the oxyacetylene welding torch.
c. oxygen is obtained commercially either by the liquid-air process or by the electrolytic process.
d. the liquid-air process furnishes the larger part of the oxygen used for welding purposes. in this process, the atmosphere or air is compressed and cooled to a point where the gases become liquid. as the temperature of the liquid air is raised, the nitrogen, in a gaseous from, is given off first, since the boiling point of liquid nitrogen is 321 F. the oxygen is given off when a temperature of-297 F is reached. these gases, having been thus separated, are then further purified and are compressed into cylinders for use.
e. in the electrolytic process, oxygen is obtained by separating water into hydrogen and oxygen by passing a direct electric current through water, to which an acid or alkali has been added, in an electric cell. the electric current breaks the water down into its chemical elements of hydrogen and oxygen collects at the positive terminal, while the hydrogen collects at the negative terminal, and each gas, having passed off through suitable pipes, is compressed in containers.