Which combination indicates suction prime has been achieved?

• A. Discharge pressure rising rapidly with no water in priming device.
• B. Suction gauge reads within expected range and there is water at priming device, then discharge pressure stabilizes.
• C. Suction gauge stays at zero and no water at priming device.
• D. Continuous popping cavitation in suction.

Answer: (B)

The key idea is that a truly primed suction means the suction line is filled with water and air has been removed, allowing the pump to draw water smoothly. When this is achieved, you’ll see the suction gauge show a normal, expected range (not a deep vacuum or zero), you’ll have water at the priming device, and the discharge pressure will settle into a steady value rather than fluctuating.

So the best indicator is a combination where the suction gauge reads within the expected range, water is present at the priming device, and the discharge pressure stabilizes. That shows the pump is drawing from a water-filled suction line and delivering water steadily.

The other scenarios indicate issues: rapid discharge pressure rise with no water in the priming device means the suction side isn’t primed yet; suction at zero with no water at the priming device means no suction and no prime achieved; continuous cavitation on the suction implies air pockets and ongoing prime failure.