Which of the following is a common sign of a suction-side air leak?

Which of the following is a common sign of a suction-side air leak?

• A. Audible air hissing
• B. Slow rise of suction gauge
• C. Sudden drops in discharge pressure
• D. Visible air bubbles in gauge line

Answer: (B)

Air entering the suction line prevents the pump from maintaining its proper vacuum, so the suction pressure trend moves toward atmospheric. In practice, this shows up as a slow, gradual rise on the suction gauge as prime is lost and the system becomes less able to pull water. That steady increase in suction-gauge reading is the most reliable, direct sign of a suction-side air leak. Audible hissing can indicate a leak, but it isn’t as dependable a sign on its own and may come from other spots. A sudden drop in discharge pressure points to issues affecting the discharge side or overall flow, not specifically a suction-side leak. Visible air bubbles in the gauge line suggest air in the gauge path rather than a suction leak in the piping, so they’re less diagnostic for the suction side during normal running.

Air entering the suction line prevents the pump from maintaining its proper vacuum, so the suction pressure trend moves toward atmospheric. In practice, this shows up as a slow, gradual rise on the suction gauge as prime is lost and the system becomes less able to pull water. That steady increase in suction-gauge reading is the most reliable, direct sign of a suction-side air leak.

Audible hissing can indicate a leak, but it isn’t as dependable a sign on its own and may come from other spots. A sudden drop in discharge pressure points to issues affecting the discharge side or overall flow, not specifically a suction-side leak. Visible air bubbles in the gauge line suggest air in the gauge path rather than a suction leak in the piping, so they’re less diagnostic for the suction side during normal running.