What Gas Is Used In Filling aeroplane Tires And Why?

which gas is filled in the tyres of aeroplane?  Isn't that an out of the box question?

Very occasionally for light aircraft air is used, however it is almost exclusively nitrogen that is used.You may wonder why oxygen should be used in preference to air as a filling gas for tires. Lets do some comparative analysis.

• Nitrogen does not support combustion

First lets analyse the composition of air. Air is about 1/5 Oxygen, and oxygen as we know is a very reactive element, especially at high pressures and temperatures. When oxygen reacts with things, the oxidation occurs and when oxidation is extremely rapid, it's becomes burning. when the aircraft lands (braking and high speed can produce dangerously high temperatures, especially if multiple sorties are flown). Hence using air would be like fuelling an already tense situation with a combustion propagating gas would would result in more fire outbreaks during landing.That's one reason nitrogen is used in off-highway and aircraft tires. These tires run so hot but they don't catch on fire. Nitrogen doesn't support combustion, so nitrogen-filled tires don't add fuel to the flames. And nitrogen helps prevent slower forms of oxidation also.  Nitrogen does not support combustion and can assist in preventing a wheel fire.

• Nitrogen does not corrode the wheels

Secondly, Air contain a good amount of moisture as water vapour. Oxygen and moisture corrodes aluminum and steel wheels. Oxygen also reacts with rubber, another type of "corrosion". When this corrosion starts, the small particles break off and form rust and dust, which can clog vavle cores, causing them to leak. The rough surfaces created from the corrosive action on the wheels leads to tire beads that don't seal properly, causing additional leaks. Nitrogen is far less reactive and it is not corrosive. It doesn't cause rust or corrosion on steel or aluminum, and it doesn't degrade rubber. Wheel surfaces stay smooth and clean, rubber remains supple and resilient.

• Nitrogen does not wear the tire like air and it reduces pressure loss in tire greatly

Thirdly, Oxygen also ages the inner liner, the thin layer of rubber inside the tire whose function is to keep air away from the carcass. As the inner liner ages, more and more air molecules can pass through it, causing more pressure losses. These pressure losses in a truck tire can average 2 psi a month as a result of the air passing through the sidewalls. As it passes through the rubber, the oxygen can also corrode the steel cords, causing them to rust too. While both nitrogen and oxygen can permeate rubber, nitrogen does it much more slowly. It might take 6 months to lose 2 psi with nitrogen, compared to just a month with air.

•  Nitrogen filled tires reduces cost greatly

Lastly, Cost. The primary cost of maintaining tires is the cost of labor to check tire pressures and top off tires with compressed air on a periodic basis. Tire pressure must be checked and the tires topped off due to the diffusion of air through the tire. Tires filled with nitrogen will not experience this diffusion and resulting loss of pressure. Tires filled with nitrogen maintain pressure for a much longer period of time than tires filled with air thereby greatly reducing the cost of maintenance.

sources : innovativebalancing.com

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