How do they keep the cabin pressurized?

Question

Yeah, how do they keep it like that? Does it have anything to do with the ram-air inlets?

Answer 1

Not normally although some systems do use ram air pressure in an emergency. But  a typical pressurization system works like this in it's simplest form.

Hot compressed air is tapped from the engine compressor sections and is fed to an air cycle machine, air conditioner to keep it simple, where it is cooled. It is then ducted throughout the cabin and cargo area. To regulate the pressure in the cabin, outflow valves open and close as necessary to maintain a constant "cabin altitude" which is typically 7-8 thousand feet. These outflow valves are controlled automatically by the pressurization controller which the crew can set as needed.

Answer 2

John B's answer is darn good.  Basically it's compressed air from the engine compressors, with a gadget for bleeding off excess air to keep the pressure correct.

In the days of piston engine airliners with pressurization, like the DC-6s, DC-7s and Constellations, the pressurized air came from the engine superchargers.  But the system works the same way.

Answer 3

vacuumed sealed like a big bag of chips

Answer 4

The pressurization can also come  from the APU.  We routinely tested the pressurization on the ground with the APU on the KC-10.  Usually at least once a week due to anti-aircraft fire or small arms fire while doing missions in the desert.  Only time we dont do it is if we think we were never engaged.  The cabin outflow valves are located forward of the right wing root.  There are three of them and if there was an incident in flight they are designed to pop and stay that way for maintenance crews to discover and trouble shoot the problem