Pumps and Hydraulics Practice Questions for Level 3 · Advanced

1. Question 1

   A centrifugal pump loses flow and begins to rattle. Wet-well level is normal. Suction vacuum is higher than usual, while discharge pressure and motor current are lower. A parallel pump on the same wet well runs normally. Which condition best fits the readings?

   1. A restriction in this pump's discharge line
   2. Wear in this pump's impeller
   3. A restriction in this pump's suction
   4. An air leak at this pump's suction joint
   Show the answer

   Answer: C. A restriction in this pump's suction

2. Question 2

   A positive-displacement sludge pump starts opening its relief valve. The valve opens at its correct pressure setting. Pump speed, sludge thickness, and sludge temperature are unchanged. Common-header pressure is normal, but pressure at the pump discharge rises sharply. What is the most likely cause?

   1. A relief valve opening below its setting
   2. A restriction between the pump and header
   3. Thicker sludge entering the pump
   4. Higher pressure in the common header
   Show the answer

   Answer: B. A restriction between the pump and header

3. Question 3

   Two identical pumps each meet their pump curve when tested alone at the same speed. Both discharge check valves open fully. With both pumps running, discharge head rises sharply, but total flow increases only slightly. Suction conditions remain adequate. What best explains the limited flow gain?

   1. One pump has lost capacity from impeller wear
   2. One check valve is blocking its pump's flow
   3. Insufficient suction head is reducing both pumps
   4. System resistance limits the gain from parallel pumping
   Show the answer

   Answer: D. System resistance limits the gain from parallel pumping

4. Question 4

   An equalization basin delivers steady flow, but discharge TSS varies sharply. Samples show much more solids near the bottom than at the surface. Incoming load is steady, and basin DO meets its target. Mixing and aeration have separate controls. Which change best stabilizes the discharged solids load?

   1. Retune the discharge pump to smooth outlet flow
   2. Increase air feed to raise basin oxygen levels
   3. Improve mixing throughout the basin
   4. Add storage volume
   Show the answer

   Answer: C. Improve mixing throughout the basin

Operator Master has 4 Level 3 · Advanced pumps and hydraulics questions, free.

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