All About Aircraft Oxygen Systems

When aircraft travel at the high altitudes that are standard for flight operations, the lack of oxygen pressure present in the atmosphere can create deadly environments for unprotected humans. As such, the negative effects of low atmospheric pressure are combated through manipulating air. Whether through increasing air pressure for more optimal breathing or by increasing the presence of oxygen within air mixtures, safe and comfortable environments may be achieved for the benefit of all operators and passengers.

For commercial airliners, the standard is to enact cabin pressurization for the internal air held within the fuselage, ensuring that there is enough oxygen to be captured by the lungs for blood saturation. To achieve this, aircraft are designed to keep a pressure value that is as close to sea-level as possible. With oxygen systems, on the other hand, the amount of oxygen within breathing air can be increased and provided to anyone without the presence of a pressurized cabin. In some instances, the aircraft oxygen system may even be portable for certain applications such as first aid.

When oxygen is in its breathable form, it is gaseous, odorless, tasteless, and colorless. In such a state, oxidation can be carried out which is when a compound or element is combined with oxygen. When oxygen is stored in its gaseous form, it is typically placed within green aircraft cylinders in a pure form. Due to the combustibility of pure oxygen, such aircraft cylinders must be placed away from any source of fuel, grease, or oil such as the combustion engine. As unpressurized aircraft can reach freezing temperatures during high-altitude operations, aviator’s aircraft cylinders are also tested for water to prevent ice buildup that may hinder oxygen delivery. Generally, water levels should never surpass .02ml per liter of oxygen to remain safe. Additionally, cylinders that contain oxygen for aviators will regularly have marked text denoting that the cylinder is the “Aviator’s Breathing Oxygen”. To ensure that aviators and other personnel are always at safe oxygen levels, portable pulse oximeters may be present to prevent hypoxia.

To produce gaseous oxygen for a variety of aircraft, air must first go through a process of liquefying. By boiling off nitrogen while managing temperature and pressure, the resulting mixture can be brought closer to pure oxygen. Another method is through the induction of electrical current to water, as oxygen and hydrogen will begin to separate. Lastly, gaseous oxygen can also be formed with a molecular sieve that separates hydrogen and oxygen as well. As molecular sieves can remove gases beyond nitrogen, such equipment can create very pure oxygen.

When oxygen reaches temperatures that fall below -183 degrees Celsius, it can enter a liquid form. Liquid oxygen, or LOX, can be contained and transported within a special container that maintains temperature and pressure, and breathable air can be provided by slowly vaporizing the contents. While only a small amount of liquid oxygen mask is allowed to oxidize at a time, the conversion to a gaseous state results in large amounts of breathable air. As such, LOX systems benefit various aircraft as they utilize only a small amount of space and weight.

While LOX systems serve many military aircraft well for their oxygen needs, other aircraft may rely on on-board oxygen generating systems (OBOGS) for their air supply. With such systems, bleed air from the turbine engine can be separated and transported into a sieve. As it is passed through, nitrogen and other gases are removed from the mixture, resulting in a clean source of pure oxygen. Due to the method of operation that OBOGS undergo, the supply of oxygen is unlimited as long as all systems are functional and are supplied bleed air from the turbine engine.

Through the various aircraft oxygen systems available, providing an aircraft and its operators with sufficient oxygen can be guaranteed for safe flight operations. At Buy NSN, we are a leading online distributor of aviation parts, offering unmatched pricing and lead-times on top global manufacturer components. If you are facing a time constraint or Aircraft on Ground requirement, we also offer expedited and same-day shipping on a number of items we offer. Begin the purchasing process with a personalized quote today when you fill out and submit an Instant RFQ form as provided on our website.


January 6, 2021

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