Abstract: A labyrinth cartridge seal having a shell and a plurality of sleeves having corresponding portions to prevent axial and radial movement therebetween and particularly a labyrinth cartridge seal for use in a compressor for compression of a gas, such as oxygen, which restricts leakage of pressurized gas to a drive mechanism such as an oil lubricated gear box, to thereby reduce the likelihood of explosions. In one embodiment, the labyrinth cartridge seal includes a shell comprising a passageway therethrough, and four spaced-apart, concentrically aligned sleeves, axially and radially supportable along the passageway and generally sealable with the shell to define three separate chambers around the shaft. The shell has three ports, each one opening onto a different one of the three separate chambers for venting or receiving a supply of buffering gas. Also disclosed is a compressor incorporating such a labyrinth cartridge seal.