During the vacuum service test, the system vacuum and pump priming device should achieve a column of mercury of at least

During the vacuum service test, the system vacuum and pump priming device should achieve a column of mercury of at least

• A. 22 Inches
• B. 18 Inches
• C. 20 Inches
• D. 24 Inches

Answer: (A)

This item tests whether the vacuum system can develop a strong enough vacuum to prime the pump. For the vacuum service test, you must achieve a column of mercury of at least twenty-two inches. Reaching this level ensures the air is effectively pulled out of the suction line and the pump priming device so the pump can fill with water and establish prime, even when there are minor leaks or line losses. It provides a reliable margin under typical field conditions, because if the vacuum is lower, priming may fail and the pump won’t draw water properly. A higher reading still meets the requirement, but twenty-two inches is the minimum standard that guarantees reliable priming.

This item tests whether the vacuum system can develop a strong enough vacuum to prime the pump. For the vacuum service test, you must achieve a column of mercury of at least twenty-two inches. Reaching this level ensures the air is effectively pulled out of the suction line and the pump priming device so the pump can fill with water and establish prime, even when there are minor leaks or line losses. It provides a reliable margin under typical field conditions, because if the vacuum is lower, priming may fail and the pump won’t draw water properly. A higher reading still meets the requirement, but twenty-two inches is the minimum standard that guarantees reliable priming.