How is the jet cabin pressurized?

The cabin of a jet is pressurized to maintain a comfortable and safe environment for passengers and crew, especially during high-altitude flights where the external air pressure is low. Here’s how the cabin pressurization system works:

1. Air Source: The pressurization system typically draws air from the aircraft’s engines, where it is compressed and cooled before being directed into the cabin.
2. Pressurization Controller: The aircraft’s pressurization system is controlled by a pressurization controller, which monitors cabin altitude and adjusts the flow of air accordingly to maintain a comfortable pressure level inside the cabin.
3. Outflow Valves: The pressurization system includes outflow valves located in the fuselage, which regulate the flow of air out of the cabin. These valves open and close as needed to maintain the desired cabin pressure.
4. Safety Valves: In addition to the outflow valves, the pressurization system also includes safety valves to prevent over-pressurization of the cabin. These valves automatically release excess air pressure if the cabin pressure exceeds a safe limit.
5. Cabin Altitude: Despite the pressurization, the cabin altitude (the equivalent altitude experienced inside the cabin) is typically maintained at a level equivalent to 6,000 to 8,000 feet above sea level, even during flights at much higher altitudes. This level of cabin altitude helps to minimize the physiological effects of altitude on passengers and crew.
6. Cabin Pressure Differential: The pressurization system maintains a pressure differential between the inside and outside of the aircraft. This pressure differential allows the cabin to remain pressurized even as the aircraft climbs to high altitudes where the external air pressure is significantly lower.

Overall, the pressurization system ensures that passengers and crew can breathe comfortably and safely throughout the duration of the flight, regardless of the altitude and external air pressure conditions.