Dry gas seals serve as a highly effective, dependable, and resilient sealing solution for compressors operating across a wide range of applications in the petrochemical, natural gas, and petroleum sectors. Their optimal performance hinges on a continuous, uninterrupted supply of clean and dry seal gas delivered within the specified flow and pressure parameters. This ensures proper lift-off of the seal faces, minimizing wear and maximizing efficiency. Both pressurized and unpressurized configurations rely on clean, dry seal gas introduced upstream of the seal to form a protective barrier against contamination from the process stream. Seal gas treatment involves the removal of particulates and aerosols to maintain purity. Dedicated seal gas support systems are engineered to deliver the required flow rate, temperature, and pressure, with these variables actively monitored and controlled. This chapter provides a qualitative overview of critical subsystems—such as dew-point management and pressure boosting—that contribute to the reliability and performance of dry gas seals.