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Gases 101: Oxygen
This is a continuation of our series on gases and toxic gas focused on oxygen.
We all need to breathe the oxygen (O2) in air to live. Air is made up of several different gases including oxygen. Normal ambient air contains an oxygen concentration of 20.9% v/v. When the oxygen level dips below 19.5% v/v, the air is considered oxygendeficient. Oxygen concentrations below 16% v/v are considered unsafe for humans. (See Figure 1).
It is often forgotten that oxygen enrichment can also cause a risk. At increased O2 levels the flammability of materials and gases increases. At levels of 24% items such as clothing can spontaneously combust. Oxyacetylene welding equipment combines oxygen and acetylene gas to produce an extremely high temperature. Other areas where hazards may arise from oxygen enriched atmospheres include areas manufacturing or storing rocket propulsion systems, products used for bleaching in the pulp and paper industry and clean water treatment facilities. Sensors have to be specially certified for use in O2 enriched atmospheres.
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