Jim Elsey is a mechanical engineer who has focused on rotating equipment design and applications for the military and several large original equipment manufacturers for 43 years in most industrial markets around the world. Elsey is an active member of the American Society of Mechanical Engineers, the National Association of Corrosion Engineers and the American Society for Metals. He is the general manager for Summit Pump Inc. and the principal of MaDDog Pump Consultants LLC. Elsey may be reached at firstname.lastname@example.org.
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.
1. Given a specific fluid to be pumped, at what viscosity range should you begin to apply viscous corrections to the hydraulic performance for a centrifugal pump?
A) 5 to 15 centipoise
2. When selecting the proper pump for a new installation, imagine that the suction pressure on your new proposed single-stage pump is more than 250 pounds per square inch gauge (psig). You do not need to waste precious time and effort to calculate the net positive suction head available (NPSHa) because the pressure is so high.
3. You are going to install a new self-priming pump where the maximum suction lift at the worst conditions would be 16 feet. You do not need to calculate the NPSHa because the fluid exhibits Newtonion properties and is at 88 F.
4. You are going to install a new self-priming pump where the suction lift at the worst conditions would be 16 feet. You do not need to calculate submergence because the suction pipe size is 6 inches and the flow is only 900 gpm.
5. You were informed by a trusted co-worker that all new industrial pumps come from the factory ready to operate. Which of the following pre-startup/installation requirements can you ignore?
F) None of the above
6. Some single-stage pumps have small vanes on the back side of the impeller. These pump-out vanes (POVs) serve what main purpose?
D) Reduce the unbalanced axial forces (hydraulic) on the impeller
8. The pump industry typically ignores velocity head (HV) when calculating the NPSHa for a given system.
F) A, B, C and D are correct.
9. The limit for a centrifugal pump impeller tip speed on slurry applications ...
F) B, C, and D are correct.
10. Many pump manufacturers will/must derate the normal shaft horsepower and torque limits under what conditions?
D) All of the above.
11. For a given size piping system, adding a second identical pump in parallel will …
C) increase the flow rate to a point determined by the system curve.
12. For a given size piping system, adding a second identical pump in series will …
C) increase the discharge pressure (head) to a point determined by the system curve.
13. A simple definition of “classic cavitation” is the formation and subsequent collapse of bubbles in the fluid stream. The potential for pump impeller damage that consequently occurs is caused by which of the following factors?
G) C, D and E apply
14. On pumps with metal wear rings (renewable), should there be a difference in material hardness of the two rings? (Assume the rotating and stationary rings with the hardness measured on the Brinell scale.)
Finish the following sentence: The difference in hardness …
F) can be explained by C and D.
15. A conventional-design centrifugal pump can handle some air entrainment in the pumped fluid and continue to operate without deleterious effects.
E) C and D are correct.