Pumps and Hydraulics Practice Questions for Level 4 · Expert

1. Question 1

   At peak flow, three influent pumps run at 55% speed and deliver 9 MGD using 210 kW. A controlled test shows two pumps at 78% also deliver 9 MGD using 165 kW, with stable wet-well level and required minimum pump flow. What change should be evaluated for normal peak operation?

   1. Keep all three pumps online
   2. Stage two pumps and verify level and energy use
   3. Run one pump above its tested range and watch wet-well level
   4. Raise the wet-well setpoint and keep all three pumps online
   Show the answer

   Answer: B. Stage two pumps and verify level and energy use

   The test delivered the same flow with stable level, acceptable pump flow, and 45 kW less demand. A controlled two-pump staging change should be verified under normal peaks before it becomes the standard sequence.

2. Question 2

   A duty sludge pump develops strong discharge pulsation after maintenance. Average flow is normal, the relief setting is unchanged, the discharge check valve passes, and dampener charge is near zero. A standby pump is available. What is the best plan?

   1. Throttle the pump discharge until pulsation falls
   2. Transfer duty and restore the dampener charge
   3. Dilute the sludge and keep the duty pump online
   4. Raise the relief setting
   Show the answer

   Answer: B. Transfer duty and restore the dampener charge

   The standby allows safe isolation, while restoring the failed dampener and verifying pressure protection addresses both the fault and return-to-service risk.

3. Question 3

   Three duty pumps still meet station flow, but only one can be removed during a planned outage. Pump 1 has elevated vibration that has stayed stable for six months; a check found correctable soft foot. Pump 2 bearing-envelope vibration doubled in two weeks, and ferrous debris in its oil is increasing. Pump 3 efficiency is down 10%, with stable vibration and high wear-ring clearance. Which work should be done first?

   1. Correct Pump 1 soft foot and realign it
   2. Replace Pump 3 wear rings to restore efficiency
   3. Keep all three pumps running until station flow falls
   4. Inspect and overhaul Pump 2 bearings
   Show the answer

   Answer: D. Inspect and overhaul Pump 2 bearings

4. Question 4

   Two approved tubing types are tested in a peristaltic phosphorus-feed pump. Type 1 costs less but loses 15% output after three days and needs weekly replacement. Type 2 holds calibration for four weeks at the same pressure and chemical strength. Both meet the pump rating. What should control the selection?

   1. Select the tubing with the lowest purchase price
   2. Use the tubing that permits the highest available pump speed
   3. Fewest tubing changes during the trial week
   4. Use verified tubing life and total operating cost
   Show the answer

   Answer: D. Use verified tubing life and total operating cost

5. Question 5

   A force main develops a pressure spike only when the lead pump stops on high wet-well drawdown. The check valve closes after reverse flow begins. A controlled test shows the variable-speed drive can ramp down over eight seconds without losing station control. What change should be tested first?

   1. Increase the pump stop speed to close the valve faster
   2. Use a controlled ramp-down and verify valve closure
   3. Hold the check valve partly closed during normal pumping
   4. Raise the wet-well stop level without checking the surge
   Show the answer

   Answer: B. Use a controlled ramp-down and verify valve closure

Operator Master has 5 Level 4 · Expert pumps and hydraulics questions, free.

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