Oxygen storage

Methods of oxygen storage for subsequent use span many approaches, including high pressures in oxygen tanks, cryogenics, oxygen-rich compounds and reaction mixtures, and chemical compounds that reversibly release oxygen upon heating or pressure change. O2 is the second most important industrial gas. Methods of oxygen storage for subsequent use span many approaches, including high pressures in oxygen tanks, cryogenics, oxygen-rich compounds and reaction mixtures, and chemical compounds that reversibly release oxygen upon heating or pressure change. O2 is the second most important industrial gas. Air is the most common source and reservoir of oxygen, containing 20.8% oxygen. This concentration is sufficient for many purposes, such as combustion of many fuels, corrosion of many metals, and breathing of animals. Most humans can function at rest with an oxygen level of 15% at one atmosphere pressure; a fuel such as methane is combustable down to 12% oxygen in nitrogen. A small room of 10 meter3 has 2.08 meter3 (2080 liters) or 2.99 kg of oxygen which would occupy 2.62 liters if it was liquid. Oxygen tanks containing pressures up to 200 bar (3000 psi) are used for industrial processes including the manufacture of steel and monel, welding and cutting, medical breathing gas, diving and as emergency backup in aircraft. A small steel tank of 16 liters water capacity with a working pressure of 139 bar (2015 psi) holds about 2150 liters of gas and weighs 28 kilograms (62 lb) empty.2150 liters of oxygen weighs about 3 kilograms (6.6 lb) Liquid oxygen in a cryogenic storage dewar (vacuum-insulated flask) is used in aerospace, submarine and gas industries. Chemical oxygen generators store oxygen in their chemical composition, and can be used only one time. Oxygen Candles contain a mix of sodium chlorate and iron powder, which when ignited smolders at about 600 °C (1,112 °F) and results in sodium chloride, iron oxide, and oxygen, about 270 liters per kg of mixture. Some commercial airliners use emergency oxygen generators containing a mixture of sodium chlorate (NaClO3), 5 percent barium peroxide (BaO2) and 1 percent potassium perchlorate (KClO4), which after ignition, reacts releasing oxygen for 12 to 22 minutes while the unit reaches 500 °F (260 °C).