FLIGHTS OF FANCY
During the safety spiel the plane staff always say that in the event of depressurisation, masks will drop from the ceiling to supply oxygen. Is the gas supplied really just oxygen or is it really more like compressed air? Is it is oxygen wouldn't this increase the fire risk?
From Chris W (Avatar)
The emergency breathing apparatus on commercial jet aircraft is fed from a set of chemical oxygen generators. An oxygen generator is a form of emergency air supply system found on newer aircraft, such as the MD-80. The generator contains extremely hazardous chemicals that combine to produce oxygen. When triggered, an oxygen generator starts a thermochemical reaction that releases intense heat up to 500oF (260oC) and produces oxygen. If the oxygen generator is removed from its protective heat shield in the airplane, it has an incendiary, if not explosive, capability. These devices are much lighter than an equivalent volume of compressed gas.
Transportation of quantities of cartridges, that are spent or in need of periodic overhaul, on passenger airlines has been banned in many countries. The ban was reinforced after they were directly linked to the crash of ValuJet Flight 592 in the US.