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Why are Airplanes pressurized?

As aircraft ascend into high altitudes, they pump air into the cabin space to pressurize it. Not only does cabin pressurization create a more comfortable environment for passengers, but it is a critical safety feature. To better understand how cabin pressurization works, this blog will cover its importance and its features.

Aircraft pressurize their cabins by pumping air into them. As their jet engines draw air in, a portion of the excess air is diverted into the cabin. The air is cooled and humidified, meaning moisture is added to it, after it has circulated into and throughout the cabin. Once the cabin reaches an ideal pressure level, the aircraft is tasked with maintaining it.

A majority of aircraft control their cabin pressure through an outflow valve. If the cabin exceeds the specified pressure, the outflow valve will open. In an open position, excess air bleeds out and the cabin pressure will drop to an appropriate level, enabling the outflow valve to close. It is important to note that some airplanes utilize other methods to regulate cabin pressure, though most modern-day commercial aircraft rely on outflow valves for this purpose.

Cabin pressurization is not only intended for passenger comfort. In fact, it is important because of the nuances between low- and high-altitude air density, as air is less dense at high altitudes than low altitudes. At ground level, the air pressure is about 14 PSI, while, at a cruising altitude of 30,000 to 40,000 feet, the air pressure is about 4 PSI.

The low air pressure associated with high-altitude flights can prevent passengers from acquiring a sufficient amount of oxygen unless cabin pressurization is provided. Low air pressure means the air is less dense; thus, it contains less oxygen. A lack of cabin pressurization may lead to medical problems like hypoxia. Hypoxia is defined as the absence of ample oxygen in the tissues to sustain proper bodily function.

That being said, it is important that airplanes are pressurized, ensuring that passengers and crew members receive an adequate amount of oxygen. Luckily, aircraft today are designed with redundancy measures and backup systems in case of pressurization failure. For instance, oxygen masks automatically drop down in front of passengers in the case of cabin pressure loss. 

There are quite a few myths and misconceptions regarding cabin pressurization that must be addressed. For example, some believe that cargo holds in passenger aircraft are not pressurized, making passengers reluctant to place their pets in the hold. Despite this misconception, this is not the case. The entire aircraft is pressurized in order to maintain efficiency. The only aircraft type that is an exception to this rule are military jets.

In very rare cases, sudden depressurization, or “explosive decompression,” may take place, meaning that people and objects are sucked out of the aircraft. However, the reality is that the crew and passengers are more likely to experience hypothermia and hypoxia in the event of depressurization. Nonetheless, either of these three occurrences put passengers and crew at risk in the absence of pressurization. 

Purchasing Union is a leading distributor of cabin pressurization parts, airplane air refuel tanks, airplane fighter components, Spacer Bearing Aircraft Gas Turb accessories,  spacer bearings, and more. With over 2 billion ready-to-purchase products, customers can easily fulfill their operational requirements. Backed by rapid lead times and unmatched cost savings, customers can rely on us for dependable aircraft parts. As we operate with AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation, you never have to worry if the items you procure from us are authentic and reliable.

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December 9, 2022
September 23, 2022

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