Whats the fuss about Nitrox and Oxygen Cleaning?
When divers start to increase the oxygen percentage in their breathing gas to reduce the amount of decompression they need there are more complications than just the fact that oxygen becomes toxic at depth. Pressurised oxygen can easily convert the barely flammable into a very combustible mix (eg: add saltpetre (oxidant) to charcoal and you convert black barbecue fuel into gunpowder). Add high pressure oxygen to rubber O-rings and…. well you get the message. Once you go above 40% oxygen the effects accelerate as the inert gas fraction falls steeply so we need to change to low flammability materials and especially lubricants. This is called oxygen service and involves using suitable materials for the job. With tanks you always use Oxygen service materials even if you are only using sub 40% mixes as, in the UK, they are normally made by pumping a measure of pure oxygen into the tank and then filling with clean compressed air. The tank valves and seals get a dose of 100% O2 and need to
