I'm doing research on life support systems for the design of a Martian scientific base, and I'm having trouble finding information about the specifics racks that keep pressure stable inside the ISS. I know the modules are sent to space already pressurized, but what keeps that pressure stable over time? I'm interested in the size and capabilities of the equipment. Is it similar to an airplane?
Wikipedia has a good overview of the ISS's ECLSS.
This paper also includes some details. In particular, the
Atmosphere Control and Supply (ACS)
The ACS subsystem provides cabin atmosphere pressure control, overpressure relief, pressure equalization, rapid depressurization detection and response, nitrogen and oxygen distribution, and nitrogen and oxygen high pressure tank recharge from Shuttle resources.
is probably the system you're looking for. Since 2014, fresh nitrogen and oxygen are delivered to the station via the
Five High Pressure Gas Tank (HPGT) ORUs... (41,369 kPa (6,000 PSI)) Nitrogen/Oxygen Recharge System (NORS) was developed.
On an aircraft, cabin air pressure is obtained via the "bleed air" system on the engines (or via electric compressors taking in outside air on newer aircraft like the 787), and continuously released through an outflow valve.