How does a dry gas seal differ from a traditional lubricated seal?

• A. It uses a gas film instead of oil lubrication.
• B. It uses water cooling instead of oil.
• C. It does not seal gas at all.
• D. It requires permanent lubrication from the crankcase.

Answer: (A)

Dry gas seals work by using the process gas itself to form a thin lubricating film between the seal faces, so there is no oil lubrication path. This gas film provides the separation and cooling needed for the rotating area, allowing high speeds and pressures while preventing oil from contaminating the gas product. Traditional lubricated seals rely on oil from a lubrication system to lubricate and cool the sealing surfaces, which can lead to oil leakage and product contamination and requires oil management. So the key difference is the lubrication medium: a gas film replaces oil lubrication.