Modern compressors usually seal the rotating shaft as it exits the compressor housing with a spring seal made of:

• A. Metal or carbon
• B. Silicon carbide
• C. Ceramic
• D. Rubber

Answer: (A)

Modern compressor shaft seals rely on a spring-driven mechanical seal to keep the rotating and stationary faces in contact as the shaft turns. The materials chosen must stand up to heat, high pressure, and the lubricated, oil-containing refrigerant environment. A metal spring provides the necessary strength and heat resistance to maintain consistent pressure across operating conditions. Carbon is often used for the seal faces because it’s self-lubricating and wears well in oily, cooled conditions, helping reduce friction and galling. Silicon carbide or ceramic can be used for some seal faces, but they aren’t used for the spring itself, and rubber wouldn’t withstand the temperatures or chemicals involved. Hence, metal or carbon are the practical, durable choices for modern spring seals.