airlock

Destined for the International Space Station, this airlock module is pictured during the final stages of its make-up in the space station manufacturing building at the Marshall Space Flight Center. The narrow section forms the airlock exit, while the wide part is the equipment lock, used to store spacesuits and equipment.

Airtight chamber that allows people to pass between areas of different pressure; also an air bubble in a pipe that impedes fluid flow. An airlock may connect an environment at ordinary pressure and an environment that has high air pressure (such as a submerged caisson used for tunnelling or building dams or bridge foundations).

An airlock may also permit someone wearing breathing apparatus to pass into an airless environment (into water from a submerged submarine or into the vacuum of space from a spacecraft).