The International Space Station (ISS) Environmental Control Life Support (ECLS) System has been developed jointly by the Boeing Corporation, Huntsville, Alabama, and Honeywell Engines & Systems, Torrance, California, to meet ISS environmental control needs. The ECLSS provides CO2 removal (Reference 1) and atmosphere pressure control for habitable modules. The ECLS functions reside in a number of USOS modules. The first module, to contain a Pressure Control Assembly (PCA) was the US Laboratory Module. It was launched in February 2001 and is fully operational on the ISS.
The PCA, a pressure control panel, interconnecting cabling, vent relief valve and 1553 bus interface to Control and Data Handling (C&DH) computers, provides pressure sensing and control of cabin pressure and has been functioning without incident 24 hours a day since becoming operational in 2001.
Honeywell Engines & Systems performed extensive qualification testing at the component level. The Boeing Company performed the system level qualification testing.