How do we get oxygen to breathe in airplanes?
The primary requirement for human survival is oxygen. How do we get oxygen at 35,000 feet in a commercial airplane? How do we breathe so comfortably?
You might already know that ‘breathable’ air is in short supply at the altitude where most commercial planes operate. However, the availability of air itself at that altitude is not actually a problem. In other words, there’s ample air at 35,000 feet, and there is sufficient oxygen in it. In fact, there’s even a reasonable amount of air at the altitude where the International space station operates!
In a nutshell, there’s plenty of air at the height where airplanes fly; it’s just that the pressure of the oxygen in that air is too low to be inhaled directly by humans.
How do airplanes manage to provide fresh air to passengers during each flight?
As a plane flies, fast-moving air enters both the jet turbine engines. This fast-moving air is compressed as it passes through layers of fan blades inside the turbine. It’s at the compressor stage that a portion of the hot air is ‘bled off’ from within the turbine. The air generated at this point is therefore known as bleed air.
Now, this bleed air is very hot, with a temperature in the range of a couple hundred degrees Fahrenheit, so it obviously must be cooled first. That’s why this hot bleed air is allowed to expand and passed through a heat exchanger so that it cools to a comfortable temperature. This cool, filtered air is then dispersed in the passenger cabin at a pressure that humans can comfortably breathe.
There’s also an outflow valve, usually located in the rear of the cabin, which ensures that the ‘used’ air is vented out of the airplane, thereby regulating air quality inside the cabin. So, the two jet turbine engines you see on either side of a plane not only keep the plane airborne by providing forward thrust, but also help maintain cabin air pressure so that we remain comfortable and conscious throughout the duration of our flight.
