A vacuum breaker is installed between equipment and a steam trap to

A vacuum breaker is installed between equipment and a steam trap to

• A. Prevent condensate from draining after shutdown
• B. Allow condensate to drain after shutdown
• C. Trip on low pressure cutoff
• D. Allow a vacuum to be pulled on the system.

Answer: (B)

The key idea is preventing a vacuum in the condensate line after a steam system shuts down so condensate can drain properly. When the line and equipment cool, the pressure can drop below atmospheric, creating a vacuum that resists or stops drainage. A vacuum breaker opens to the atmosphere when a vacuum starts to form, letting air into the line and breaking that negative pressure. Once the vacuum is broken, condensate can flow out and drain toward the trap or drain, enabling effective drainage after shutdown. It’s not about pulling a vacuum or preventing drainage—it’s about admitting air to stop vacuum so drainage can occur smoothly.

The key idea is preventing a vacuum in the condensate line after a steam system shuts down so condensate can drain properly. When the line and equipment cool, the pressure can drop below atmospheric, creating a vacuum that resists or stops drainage. A vacuum breaker opens to the atmosphere when a vacuum starts to form, letting air into the line and breaking that negative pressure. Once the vacuum is broken, condensate can flow out and drain toward the trap or drain, enabling effective drainage after shutdown. It’s not about pulling a vacuum or preventing drainage—it’s about admitting air to stop vacuum so drainage can occur smoothly.