During a ______ purge, there is a continuous flow of inert gas through the vessel.

• A. Vacuum purge
• B. Sweep purge
• C. Pressure purge
• D. Normal purge

Answer: (B)

During a sweep purge, inert gas flows continuously through the vessel, sweeping air and residual vapors out as it moves from inlet to outlet. That steady, directional flow ensures the interior is effectively displaced by the inert atmosphere, reducing the chance that air pockets or reactive vapors linger and creating a safer environment before maintenance or processing resumes. This approach differs from a vacuum purge, which relies on removing air by lowering pressure rather than maintaining a constant gas sweep; a pressure purge, which introduces gas at higher pressure but may not guarantee a thorough sweep across the whole vessel; and a normal purge, which may not provide the controlled, unidirectional flow needed for a complete displacement of residual vapors.