AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

Aircraft Cabin Pressurization System

While there are various aircraft that may be unpressurized, the majority of commercial airliners and business aircraft will utilize a pressurization system for the benefit of passengers and crew members. At the high altitudes that many aircraft operate at, the presence of low air pressure can result in insufficient oxygen density that is hazardous to individuals. While an oxygen tank may be used to combat this, such solutions are not efficient for aircraft in which many individuals are aboard. As such, the pressurization control system is implemented for numerous aircraft in order to protect all individuals from hypoxia.

Cabin pressurization is intended to bring the air pressure within a cabin as close to sea level as possible. The method of pressurization depends upon a number of components, but the basic operation consists of regulating the amount of air that flows out of the cabin. To achieve this, the air condition system forces air into the cabin, and the cabin pressure controller, outflow valve, safety valve, and negative pressure relief valve all ensure that airflow is managed efficiently.

The cabin pressure controller, or CPC, is a device that is used to manage the pressure of cabin air. For its functionality, each cabin pressure controller will contain both a system interface and a valve motor system. With the controller, the cabin pressure is rate-controlled up to an altitude value of 8,000 feet. With the use of the outflow valve, the pressure within the cabin can be maintained as the valve will open, close, and modulate as necessary throughout the duration of the flight.

Over-pressurization can be a hazard, and thus safety valves are put in place. The positive pressure relief valve serves to open at differential pressures so that air may flow out of the cabin when needed. Generally, the valves are designed so that they open upon reaching a value between 8 and 10 psid. Additionally, such valves can also be operated manually so that they can serve as a dump valve as necessary. As a fail-safe device that can reduce pressure when an outflow valve fails, such components are very beneficial for the protection of the aircraft structure.

The negative pressure relief valve serves to deter vacuum pressure which can damage the structure of an aircraft. Vacuum pressure is most common during a rapid descent, and the negative pressure relief valve utilizes a spring-loaded configuration to open inwards for ambient air to enter the cabin. If there is too much negative pressure present, the cabin door may not open correctly or easily. Additionally, high amounts of negative pressure can damage various structures and components due to the fact that cabin pressure should always be higher than ambient pressure.

The last major component of the cabin pressurization system is the ventilation system. With ventilation, the rate of air entering and exiting the cabin can be managed. In order to pressurize air, supply air is pumped into the cabin at a higher rate than the speed at which air is permitted to leave. Utilizing differential pressure, the ventilation system can remove air through the use of suction.

At Internet for Aviation, we serve as a leading supplier of aircraft pressurization components and more. With over 2 billion items readily available for purchase, we are your sourcing solution for all aviation parts you need that are new, used, or obsolete. As you explore our offered components, we invite you to fill out and submit an Instant RFQ form for the items that you are interested in and a dedicated account manager will be in touch within 15 minutes or less to offer a personalized quote. Get started today and see how Internet for Aviation is revolutionizing the procurement process for the benefit of our customers.


Semiconductor's Certifications and Memberships
The only independent
distributor with a
  • All orders are fulfilled in the USA.
  • All shipments must comply with U.S.A export laws.
  • No exceptions.
fallen heroes fund logo

“We Proudly Support Intrepid Fallen Heroes Fund that serves United States Military Personal experiencing the Invisible Wounds of War : Traumatic Brain Injury (TBI) and Post Traumatic Stress (PTS). Please visit website ( and help in their valiant effort”.

Thank You for Visiting.

We Hope that You Will Visit Us Again the Next Time You Need NSN Parts and Make Us Your Strategic Purchasing Partner.

Request for Quote

We use cookies to ensure that we give you the excellent experience on our website. If you continue to use this site we will assume that you are happy with it.