These are the answers to the Pump Ninja Quiz that was published in the July issue.

Below are the questions with the correct answer only. Total up the number of answers you got correct and see if you are a Pump Ninja at the end of the article. If you missed the issue, take this quiz here.

Let us know how you did by tweeting us @PumpSystemsMag with #PumpNinja or by emailing us at

1. A centrifugal pump converts mechanical energy to pressure energy (head). It works…
b) because the impeller imparts a velocity to the fluid, and the casing subsequently collects and converts the velocity to pressure head.

2. If you double the operating speed of a centrifugal pump…
d) all of the above: a, b and c.

3. Refer to the same pump that you doubled the speed on in the previous question: There would be no need to change the pipe sizes because the higher fluid velocity would compensate for the added friction losses.
b) False

4. NPSH is an acronym for…
c) net positive suction head

5. NPSH3 is an acronym used by pump engineers to designate…
c) the point during an NPSHR test where the developed head will drop by 3 percent with the flow rate held constant.

6. You have a pump with a “flooded suction,” so there is no valid reason to calculate the NPSHA, and to do so would be a waste of time and effort.
b) False

7. Your new self-priming pump is installed at a location that is basically at sea level. Ignoring friction losses and assuming the water you wish to pump is at or below 70 F (21.1 C), how high is your theoretical maximum suction lift?
c) 33.95 feet

8. You are installing a new American National Standards Institute (ANSI) B73.1M pump package that is motor-driven. The motor is 20 horsepower (hp), 460 volt, 3 phase and 60 Hertz. It operates at 3,550 rpm with a service factor of 1.15. It is Insulation Class G, totally enclosed fan-cooled (TEFC) enclosure and rated for chemical duty. You are upset that the manufacturer has not installed the coupling but has instead shipped it in a separate box attached to the baseplate. You …
c) realize that the coupling was left off because you have yet to perform a phase rotation check, set the mechanical seal and perform the alignment.

9. Is it 100 percent acceptable to have some water mixed with the oil in the pump bearing housing?
e) None of the above

10. A stainless steel (ASM rated 316-SS) pump with 150-pound ANSI flanges is perfectly acceptable to use in which application?
d) None of the above. These applications are not acceptable.

11. You can operate any variable speed industrial centrifugal pump at extremely slow speeds (less than 200 rpm) for as long as you want without any ill effects to the pump, especially if it is multistage with close clearance wear rings.
b) False

12. A typical centrifugal pump operating backward (rotation in opposite direction) will…
d) will generate about 50 percent of its normal flow and, depending on the specific speed of the impeller, produce 45 to 65 percent of the normal head.

13. Water will boil at what temperature (F)?
e) It depends on the pressure.

14. Cavitation is defined as…
c) the formation of vapor bubbles in the fluid due to a drop below its vapor pressure and the subsequent collapse of those bubbles as the fluid moves to an area of higher pressure.

15. If you cannot hear the pump cavitating, then it is not cavitating.
b) False

16. Which fluid, when subjected to cavitation conditions, will normally create the most damage in a pump (assuming all other conditions are the same)?
e) water at 68 F

17. Specific speed (Ns) is generally defined as…
d) a calculation method (tool) and subsequent result (with no units) to define the impeller geometry and performance characteristics.

18. Which best describes suction specific speed (Nss)?
a) A concept calculation (no units in the answer) initially postulated by a guy named Igor in his kitchen with several other pump engineers over breakfast on a Saturday morning in the 1930s

19. Submergence is defined as…
c) the vertical distance from the pump inlet pipe to the top of the liquid being pumped.

20. Submergence is an important parameter to the pump because…
e) Both b and c.

21. Pump shafts have hp and speed limitations. Which of these apply?
d) All of the above.

22. When starting up a centrifugal pump, the suction valve should always be…
b) fully open.

23. When starting up a centrifugal pump, the discharge valve should be…
d) It depends. All of the above can apply or not because it depends on the pump specific speed, the system design and operating procedures.

24. If you use an expensive coupling that can withstand misalignment (per the manufacturer), you don’t need to do a time-consuming alignment process (the driver to the pump).
b) False

25. Viscosity corrections for hydraulic performance are not required or necessary on a centrifugal pump if the fluid viscosity is below 500 centipoise.
b) False

Assume a single-stage horizontal end suction centrifugal pump is operating at 1,750 rpm and the fluid is water at 65 F. Where the pump operates on its performance curve (flow and head) is determined by which, if any, of the following?
a) Where the pump curve intersects the system curve

Now add up the answers you got correct and see if you are a Pump Ninja.

Let us know how you did by tweeting us @PumpSystemsMag with #PumpNinja or by emailing us at
pump ninja

Pump Neophyte — 10 or less correct

If you correctly answered 10 or fewer questions, you are a Pump Neophyte. Remember: Pump Ninjas are not born; they are forged by the hands of masters under high-pressure situations with the intense fire that lies in the heart of the most hardened veterans of this trade. You must learn to crawl before you can walk. Begin by surrounding yourself with experienced soldiers who can set you on a long and painful—but immensely rewarding—journey to Pump Ninja.

Pump Grasshopper — 11 to 15 correct

If you correctly answered between 11 and 15 questions, you are a Pump Grasshopper. Your quest for knowledge is gaining traction, but your journey still has many twists and turns shrouded in darkness. You must learn to expect the unexpected, anticipate what is lurking around the next corner. Your path to growth involves learning from masters in the field. Seek out their guidance at once to advance your skills in hope of becoming a Pump Ninja.

Pump Assassin — 16 to 19 correct

If you correctly answered between 16 and 19 questions, you are a Pump Assassin. The ways of the Pump Ninja are growing stronger in you, but your future leaves much room to learn and advance your skills. Your experience involves many encounters with adversaries in the pump world—some successes, some defeats. But you continue to press forward with a drive that can lead to mastery.

Pump Warrior — 20 to 23 correct

If you correctly answered between 20 and 23 questions, you are a Pump Warrior. You have sharpened your skills throughout many fierce engagements in the pump world. You will courageously run into the face of any conflict, and the outcome is nearly always victorious for you. With your continued dedication and passion for improvement, you will one day soon become a Pump Ninja.

Pump Ninja — 24 or more correct

If you correctly answered 24 or more questions, you are a Pump Ninja. You are capable of competently and swiftly handling the most dangerous and challenging situations in the pump world. No foe is too great for the Pump Ninja. Your years of experience and vast wisdom make you a champion among your peers. Bow before the Pump Ninja.

Congratulations to all our Pump Ninjas!

Let us know how you did by tweeting us @PumpSystemsMag with #PumpNinja or by emailing us at