What is used to prevent air from being drawn out of a vessel with swirling liquid at a drain?

What is used to prevent air from being drawn out of a vessel with swirling liquid at a drain?

• A. Vortex Breaker
• B. Vent Cap
• C. Air Trap
• D. Air Release Valve

Answer: (A)

When a liquid is drained from a vessel, the swirling flow tends to form a vortex that can reach the surface and pull air into the suction line. That air entrainment breaks the pump’s prime and can cause cavitation or loss of flow. A vortex breaker acts as a baffle or plate placed at the drain to disrupt the swirling motion. By breaking the vortex, it keeps the liquid surface from deepening into a strong whirl, so air isn’t sucked into the drain. This keeps the line primed and prevents air entrainment. Vent caps, while useful for releasing or admitting gas at the top, don’t stop air from being drawn in at the drain. An air release valve vents trapped air in a system—again, not preventing air ingress at the drain. An air trap isn’t the mechanism used here.

When a liquid is drained from a vessel, the swirling flow tends to form a vortex that can reach the surface and pull air into the suction line. That air entrainment breaks the pump’s prime and can cause cavitation or loss of flow.

A vortex breaker acts as a baffle or plate placed at the drain to disrupt the swirling motion. By breaking the vortex, it keeps the liquid surface from deepening into a strong whirl, so air isn’t sucked into the drain. This keeps the line primed and prevents air entrainment.

Vent caps, while useful for releasing or admitting gas at the top, don’t stop air from being drawn in at the drain. An air release valve vents trapped air in a system—again, not preventing air ingress at the drain. An air trap isn’t the mechanism used here.