Gas Booster Gas / Air separation explained

The image to the left shows the sealing arrangement which separates the Air (Drive) section from the High Pressure (HP) Gas side of the booster - this is highlighted within the Red circle.

If in the unlikely event High pressure gas or Air drive was to leak past the seals ref 61....74 below then the escaping gas will take the path of least resistance an flow out of the Vent port thus preventing HP gas getting into the Air drive section and vice versa.