What is separation gas?

• A. Labyrinth on the outboard side of the seal prevents oil leakage to the bearing housing
• B. A gas used to separate stages
• C. A gas used to cool the bearing housing
• D. A gas used to vent the compressor to atmosphere

Answer: (A)

Separation gas is the gas used on the outboard side of the seal to keep oil from migrating into the bearing housing. It creates a barrier around the seal and sweeps any oil droplets away from the bearing area, helping to maintain an oil-free bearing environment. The labyrinth arrangement helps define and maintain that gas path, confining any leakage to the oil sump rather than letting it reach the bearing housing. In practice, this gas is typically clean air or nitrogen and is kept at a slight pressure so it effectively blocks oil ingress. This function is distinct from roles like separating stages, cooling the bearing housing, or venting the compressor to atmosphere.